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Fixed #16187 -- refactored ORM lookup system

Allowed users to specify which lookups or transforms ("nested lookus")
are available for fields. The implementation is now class based.

Squashed commit of the following:

commit fa7a719
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Jan 18 10:53:24 2014 +0200

    Added lookup registration API docs

commit eb1c8ce
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Tue Jan 14 18:59:36 2014 +0200

    Release notes and other minor docs changes

commit 11501c2
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sun Jan 12 20:53:03 2014 +0200

    Forgot to add custom_lookups tests in prev commit

commit 83173b9
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sun Jan 12 19:59:12 2014 +0200

    Renamed Extract -> Transform

commit 3b18d9f
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sun Jan 12 19:51:53 2014 +0200

    Removed suggestion of temporary lookup registration from docs

commit 21d0c76
Merge: 2509006 f2dc442
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sun Jan 12 09:38:23 2014 -0800

    Merge pull request #2 from mjtamlyn/lookups_3

    Reworked custom lookups docs.

commit f2dc442
Author: Marc Tamlyn <marc.tamlyn@gmail.com>
Date:   Sun Jan 12 13:15:05 2014 +0000

    Reworked custom lookups docs.

    Mostly just formatting and rewording, but also replaced the example
    using ``YearExtract`` to  use an example which is unlikely to ever be
    possible directly in the ORM.

commit 2509006
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sun Jan 12 13:19:13 2014 +0200

    Removed unused import

commit 4fba5df
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Jan 11 22:34:41 2014 +0200

    Added docs to index

commit 6d53963
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Jan 11 22:10:24 2014 +0200

    Dead code removal

commit f9cc039
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Jan 11 19:00:43 2014 +0200

    A new try for docs

commit 33aa18a
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Jan 11 14:57:12 2014 +0200

    Renamed get_cols to get_group_by_cols

commit c7d5f86
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Jan 11 14:45:53 2014 +0200

    Altered query string customization for backends vendors

    The new way is trying to call first method 'as_' + connection.vendor.
    If that doesn't exist, then call as_sql().

    Also altered how lookup registration is done. There is now
    RegisterLookupMixin class that is used by Field, Extract and
    sql.Aggregate. This allows one to register lookups for extracts and
    aggregates in the same way lookup registration is done for fields.

commit 90e7004
Merge: 66649ff f7c2c0a
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Jan 11 13:21:01 2014 +0200

    Merge branch 'master' into lookups_3

commit 66649ff
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Jan 11 13:16:01 2014 +0200

    Some rewording in docs

commit 31b8faa
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sun Dec 29 15:52:29 2013 +0200

    Cleanup based on review comments

commit 1016159
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Dec 28 18:37:04 2013 +0200

    Proof-of-concept fix for #16731

    Implemented only for SQLite and PostgreSQL, and only for startswith
    and istartswith lookups.

commit 193cd09
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Dec 28 17:57:58 2013 +0200

    Fixed #11722 -- iexact=F() produced invalid SQL

commit 08ed3c3
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Dec 21 23:59:52 2013 +0200

    Made Lookup and Extract available from django.db.models

commit b99c8d8
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Dec 21 23:06:29 2013 +0200

    Fixed review notes by Loic

commit 049eebc
Merge: ed8fab7 b80a835
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Dec 21 22:53:10 2013 +0200

    Merge branch 'master' into lookups_3

    Conflicts:
    	django/db/models/fields/__init__.py
    	django/db/models/sql/compiler.py
    	django/db/models/sql/query.py
    	tests/null_queries/tests.py

commit ed8fab7
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Dec 21 22:47:23 2013 +0200

    Made Extracts aware of full lookup path

commit 27a57b7
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sun Dec 1 21:10:11 2013 +0200

    Removed debugger import

commit 074e0f5
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sun Dec 1 21:02:16 2013 +0200

    GIS lookup support added

commit 760e28e
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sun Dec 1 20:04:31 2013 +0200

    Removed usage of Constraint, used Lookup instead

commit eac4776
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sun Dec 1 02:22:30 2013 +0200

    Minor cleanup of Lookup API

commit 2adf504
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sun Dec 1 02:14:19 2013 +0200

    Added documentation, polished implementation

commit 32c0435
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Nov 30 23:10:15 2013 +0200

    Avoid OrderedDict creation on lookup aggregate check

commit 7c8b3a3
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Sat Nov 30 23:04:34 2013 +0200

    Implemented nested lookups

    But there is no support of using lookups outside filtering yet.

commit 4d219d4
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date:   Wed Nov 27 22:07:30 2013 +0200

    Initial implementation of custom lookups
  • Loading branch information...
commit 20bab2cf9d02a5c6477d8aac066a635986e0d3f3 1 parent b87c59b
@akaariai akaariai authored
Showing with 1,324 additions and 185 deletions.
  1. +3 −2 django/contrib/contenttypes/generic.py
  2. +1 −3 django/contrib/gis/db/backends/mysql/operations.py
  3. +1 −4 django/contrib/gis/db/backends/oracle/operations.py
  4. +1 −4 django/contrib/gis/db/backends/postgis/operations.py
  5. +1 −4 django/contrib/gis/db/backends/spatialite/operations.py
  6. +15 −0 django/contrib/gis/db/models/constants.py
  7. +6 −0 django/contrib/gis/db/models/fields.py
  8. +28 −0 django/contrib/gis/db/models/lookups.py
  9. +1 −13 django/contrib/gis/db/models/sql/query.py
  10. +3 −0  django/db/backends/__init__.py
  11. +6 −0 django/db/backends/postgresql_psycopg2/base.py
  12. +5 −0 django/db/backends/sqlite3/base.py
  13. +1 −0  django/db/models/__init__.py
  14. +5 −4 django/db/models/aggregates.py
  15. +6 −3 django/db/models/fields/__init__.py
  16. +22 −14 django/db/models/fields/related.py
  17. +317 −0 django/db/models/lookups.py
  18. +9 −1 django/db/models/sql/aggregates.py
  19. +38 −25 django/db/models/sql/compiler.py
  20. +16 −7 django/db/models/sql/datastructures.py
  21. +3 −3 django/db/models/sql/expressions.py
  22. +111 −68 django/db/models/sql/query.py
  23. +8 −12 django/db/models/sql/subqueries.py
  24. +18 −9 django/db/models/sql/where.py
  25. +6 −0 docs/howto/custom-model-fields.txt
  26. +2 −1  docs/index.txt
  27. +336 −0 docs/ref/models/custom-lookups.txt
  28. +7 −0 docs/ref/models/fields.txt
  29. +1 −0  docs/ref/models/index.txt
  30. +3 −0  docs/ref/models/querysets.txt
  31. +21 −0 docs/releases/1.7.txt
  32. +1 −1  tests/aggregation/tests.py
  33. 0  tests/custom_lookups/__init__.py
  34. +13 −0 tests/custom_lookups/models.py
  35. +279 −0 tests/custom_lookups/tests.py
  36. +20 −1 tests/expressions/tests.py
  37. +0 −3  tests/null_queries/tests.py
  38. +10 −3 tests/queries/tests.py
View
5 django/contrib/contenttypes/generic.py
@@ -12,7 +12,7 @@
from django.db.models import signals
from django.db.models.fields.related import ForeignObject, ForeignObjectRel
from django.db.models.related import PathInfo
-from django.db.models.sql.where import Constraint
+from django.db.models.sql.datastructures import Col
from django.forms import ModelForm, ALL_FIELDS
from django.forms.models import (BaseModelFormSet, modelformset_factory,
modelform_defines_fields)
@@ -236,7 +236,8 @@ def get_extra_restriction(self, where_class, alias, remote_alias):
field = self.rel.to._meta.get_field_by_name(self.content_type_field_name)[0]
contenttype_pk = self.get_content_type().pk
cond = where_class()
- cond.add((Constraint(remote_alias, field.column, field), 'exact', contenttype_pk), 'AND')
+ lookup = field.get_lookup('exact')(Col(remote_alias, field, field), contenttype_pk)
+ cond.add(lookup, 'AND')
return cond
def bulk_related_objects(self, objs, using=DEFAULT_DB_ALIAS):
View
4 django/contrib/gis/db/backends/mysql/operations.py
@@ -49,9 +49,7 @@ def get_geom_placeholder(self, value, srid):
return placeholder
def spatial_lookup_sql(self, lvalue, lookup_type, value, field, qn):
- alias, col, db_type = lvalue
-
- geo_col = '%s.%s' % (qn(alias), qn(col))
+ geo_col, db_type = lvalue
lookup_info = self.geometry_functions.get(lookup_type, False)
if lookup_info:
View
5 django/contrib/gis/db/backends/oracle/operations.py
@@ -231,10 +231,7 @@ def transform_value(val, srid):
def spatial_lookup_sql(self, lvalue, lookup_type, value, field, qn):
"Returns the SQL WHERE clause for use in Oracle spatial SQL construction."
- alias, col, db_type = lvalue
-
- # Getting the quoted table name as `geo_col`.
- geo_col = '%s.%s' % (qn(alias), qn(col))
+ geo_col, db_type = lvalue
# See if a Oracle Geometry function matches the lookup type next
lookup_info = self.geometry_functions.get(lookup_type, False)
View
5 django/contrib/gis/db/backends/postgis/operations.py
@@ -478,10 +478,7 @@ def spatial_lookup_sql(self, lvalue, lookup_type, value, field, qn):
(alias, col, db_type), the lookup type string, lookup value, and
the geometry field.
"""
- alias, col, db_type = lvalue
-
- # Getting the quoted geometry column.
- geo_col = '%s.%s' % (qn(alias), qn(col))
+ geo_col, db_type = lvalue
if lookup_type in self.geometry_operators:
if field.geography and not lookup_type in self.geography_operators:
View
5 django/contrib/gis/db/backends/spatialite/operations.py
@@ -324,10 +324,7 @@ def spatial_lookup_sql(self, lvalue, lookup_type, value, field, qn):
[a tuple of (alias, column, db_type)], lookup type, lookup
value, the model field, and the quoting function.
"""
- alias, col, db_type = lvalue
-
- # Getting the quoted field as `geo_col`.
- geo_col = '%s.%s' % (qn(alias), qn(col))
+ geo_col, db_type = lvalue
if lookup_type in self.geometry_functions:
# See if a SpatiaLite geometry function matches the lookup type.
View
15 django/contrib/gis/db/models/constants.py
@@ -0,0 +1,15 @@
+from django.db.models.sql.constants import QUERY_TERMS
+
+GIS_LOOKUPS = {
+ 'bbcontains', 'bboverlaps', 'contained', 'contains',
+ 'contains_properly', 'coveredby', 'covers', 'crosses', 'disjoint',
+ 'distance_gt', 'distance_gte', 'distance_lt', 'distance_lte',
+ 'dwithin', 'equals', 'exact',
+ 'intersects', 'overlaps', 'relate', 'same_as', 'touches', 'within',
+ 'left', 'right', 'overlaps_left', 'overlaps_right',
+ 'overlaps_above', 'overlaps_below',
+ 'strictly_above', 'strictly_below'
+}
+ALL_TERMS = GIS_LOOKUPS | QUERY_TERMS
+
+__all__ = ['ALL_TERMS', 'GIS_LOOKUPS']
View
6 django/contrib/gis/db/models/fields.py
@@ -2,6 +2,8 @@
from django.db.models.sql.expressions import SQLEvaluator
from django.utils.translation import ugettext_lazy as _
from django.contrib.gis import forms
+from django.contrib.gis.db.models.constants import GIS_LOOKUPS
+from django.contrib.gis.db.models.lookups import GISLookup
from django.contrib.gis.db.models.proxy import GeometryProxy
from django.contrib.gis.geometry.backend import Geometry, GeometryException
from django.utils import six
@@ -284,6 +286,10 @@ def get_placeholder(self, value, connection):
"""
return connection.ops.get_geom_placeholder(self, value)
+for lookup_name in GIS_LOOKUPS:
+ lookup = type(lookup_name, (GISLookup,), {'lookup_name': lookup_name})
+ GeometryField.register_lookup(lookup)
+
# The OpenGIS Geometry Type Fields
class PointField(GeometryField):
View
28 django/contrib/gis/db/models/lookups.py
@@ -0,0 +1,28 @@
+from django.db.models.lookups import Lookup
+from django.db.models.sql.expressions import SQLEvaluator
+
+
+class GISLookup(Lookup):
+ def as_sql(self, qn, connection):
+ from django.contrib.gis.db.models.sql import GeoWhereNode
+ # We use the same approach as was used by GeoWhereNode. It would
+ # be a good idea to upgrade GIS to use similar code that is used
+ # for other lookups.
+ if isinstance(self.rhs, SQLEvaluator):
+ # Make sure the F Expression destination field exists, and
+ # set an `srid` attribute with the same as that of the
+ # destination.
+ geo_fld = GeoWhereNode._check_geo_field(self.rhs.opts, self.rhs.expression.name)
+ if not geo_fld:
+ raise ValueError('No geographic field found in expression.')
+ self.rhs.srid = geo_fld.srid
+ db_type = self.lhs.output_type.db_type(connection=connection)
+ params = self.lhs.output_type.get_db_prep_lookup(
+ self.lookup_name, self.rhs, connection=connection)
+ lhs_sql, lhs_params = self.process_lhs(qn, connection)
+ # lhs_params not currently supported.
+ assert not lhs_params
+ data = (lhs_sql, db_type)
+ spatial_sql, spatial_params = connection.ops.spatial_lookup_sql(
+ data, self.lookup_name, self.rhs, self.lhs.output_type, qn)
+ return spatial_sql, spatial_params + params
View
14 django/contrib/gis/db/models/sql/query.py
@@ -1,6 +1,7 @@
from django.db import connections
from django.db.models.query import sql
+from django.contrib.gis.db.models.constants import ALL_TERMS
from django.contrib.gis.db.models.fields import GeometryField
from django.contrib.gis.db.models.sql import aggregates as gis_aggregates
from django.contrib.gis.db.models.sql.conversion import AreaField, DistanceField, GeomField
@@ -9,19 +10,6 @@
from django.contrib.gis.measure import Area, Distance
-ALL_TERMS = set([
- 'bbcontains', 'bboverlaps', 'contained', 'contains',
- 'contains_properly', 'coveredby', 'covers', 'crosses', 'disjoint',
- 'distance_gt', 'distance_gte', 'distance_lt', 'distance_lte',
- 'dwithin', 'equals', 'exact',
- 'intersects', 'overlaps', 'relate', 'same_as', 'touches', 'within',
- 'left', 'right', 'overlaps_left', 'overlaps_right',
- 'overlaps_above', 'overlaps_below',
- 'strictly_above', 'strictly_below'
-])
-ALL_TERMS.update(sql.constants.QUERY_TERMS)
-
-
class GeoQuery(sql.Query):
"""
A single spatial SQL query.
View
3  django/db/backends/__init__.py
@@ -673,6 +673,9 @@ class BaseDatabaseFeatures(object):
# What kind of error does the backend throw when accessing closed cursor?
closed_cursor_error_class = ProgrammingError
+ # Does 'a' LIKE 'A' match?
+ has_case_insensitive_like = True
+
def __init__(self, connection):
self.connection = connection
View
6 django/db/backends/postgresql_psycopg2/base.py
@@ -62,6 +62,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
supports_combined_alters = True
nulls_order_largest = True
closed_cursor_error_class = InterfaceError
+ has_case_insensitive_like = False
class DatabaseWrapper(BaseDatabaseWrapper):
@@ -83,6 +84,11 @@ class DatabaseWrapper(BaseDatabaseWrapper):
'iendswith': 'LIKE UPPER(%s)',
}
+ pattern_ops = {
+ 'startswith': "LIKE %s || '%%%%'",
+ 'istartswith': "LIKE UPPER(%s) || '%%%%'",
+ }
+
Database = Database
def __init__(self, *args, **kwargs):
View
5 django/db/backends/sqlite3/base.py
@@ -334,6 +334,11 @@ class DatabaseWrapper(BaseDatabaseWrapper):
'iendswith': "LIKE %s ESCAPE '\\'",
}
+ pattern_ops = {
+ 'startswith': "LIKE %s || '%%%%'",
+ 'istartswith': "LIKE UPPER(%s) || '%%%%'",
+ }
+
Database = Database
def __init__(self, *args, **kwargs):
View
1  django/db/models/__init__.py
@@ -17,6 +17,7 @@
from django.db.models.fields.proxy import OrderWrt # NOQA
from django.db.models.deletion import ( # NOQA
CASCADE, PROTECT, SET, SET_NULL, SET_DEFAULT, DO_NOTHING, ProtectedError)
+from django.db.models.lookups import Lookup, Transform # NOQA
from django.db.models import signals # NOQA
View
9 django/db/models/aggregates.py
@@ -15,10 +15,11 @@ def refs_aggregate(lookup_parts, aggregates):
default annotation names we must check each prefix of the lookup_parts
for match.
"""
- for i in range(len(lookup_parts) + 1):
- if LOOKUP_SEP.join(lookup_parts[0:i]) in aggregates:
- return True
- return False
+ for n in range(len(lookup_parts) + 1):
+ level_n_lookup = LOOKUP_SEP.join(lookup_parts[0:n])
+ if level_n_lookup in aggregates:
+ return aggregates[level_n_lookup], lookup_parts[n:]
+ return False, ()
class Aggregate(object):
View
9 django/db/models/fields/__init__.py
@@ -11,6 +11,7 @@
from django.apps import apps
from django.db import connection
+from django.db.models.lookups import default_lookups, RegisterLookupMixin
from django.db.models.query_utils import QueryWrapper
from django.conf import settings
from django import forms
@@ -80,7 +81,7 @@ def _empty(of_cls):
@total_ordering
-class Field(object):
+class Field(RegisterLookupMixin):
"""Base class for all field types"""
# Designates whether empty strings fundamentally are allowed at the
@@ -101,6 +102,7 @@ class Field(object):
'unique': _('%(model_name)s with this %(field_label)s '
'already exists.'),
}
+ class_lookups = default_lookups.copy()
# Generic field type description, usually overridden by subclasses
def _description(self):
@@ -514,8 +516,7 @@ def get_prep_lookup(self, lookup_type, value):
except ValueError:
raise ValueError("The __year lookup type requires an integer "
"argument")
-
- raise TypeError("Field has invalid lookup: %s" % lookup_type)
+ return self.get_prep_value(value)
def get_db_prep_lookup(self, lookup_type, value, connection,
prepared=False):
@@ -564,6 +565,8 @@ def get_db_prep_lookup(self, lookup_type, value, connection,
return connection.ops.year_lookup_bounds_for_date_field(value)
else:
return [value] # this isn't supposed to happen
+ else:
+ return [value]
def has_default(self):
"""
View
36 django/db/models/fields/related.py
@@ -5,9 +5,11 @@
from django.db.models import signals, Q
from django.db.models.fields import (AutoField, Field, IntegerField,
PositiveIntegerField, PositiveSmallIntegerField, FieldDoesNotExist)
+from django.db.models.lookups import IsNull
from django.db.models.related import RelatedObject, PathInfo
from django.db.models.query import QuerySet
from django.db.models.deletion import CASCADE
+from django.db.models.sql.datastructures import Col
from django.utils.encoding import smart_text
from django.utils import six
from django.utils.deprecation import RenameMethodsBase
@@ -987,6 +989,11 @@ def set_field_name(self):
# example custom multicolumn joins currently have no remote field).
self.field_name = None
+ def get_lookup_constraint(self, constraint_class, alias, targets, sources, lookup_type,
+ raw_value):
+ return self.field.get_lookup_constraint(constraint_class, alias, targets, sources,
+ lookup_type, raw_value)
+
class ManyToOneRel(ForeignObjectRel):
def __init__(self, field, to, field_name, related_name=None, limit_choices_to=None,
@@ -1193,14 +1200,16 @@ def get_reverse_path_info(self):
pathinfos = [PathInfo(from_opts, opts, (opts.pk,), self.rel, not self.unique, False)]
return pathinfos
- def get_lookup_constraint(self, constraint_class, alias, targets, sources, lookup_type,
+ def get_lookup_constraint(self, constraint_class, alias, targets, sources, lookups,
raw_value):
- from django.db.models.sql.where import SubqueryConstraint, Constraint, AND, OR
+ from django.db.models.sql.where import SubqueryConstraint, AND, OR
root_constraint = constraint_class()
assert len(targets) == len(sources)
+ if len(lookups) > 1:
+ raise exceptions.FieldError('Relation fields do not support nested lookups')
+ lookup_type = lookups[0]
def get_normalized_value(value):
-
from django.db.models import Model
if isinstance(value, Model):
value_list = []
@@ -1221,28 +1230,27 @@ def get_normalized_value(value):
[source.name for source in sources], raw_value),
AND)
elif lookup_type == 'isnull':
- root_constraint.add(
- (Constraint(alias, targets[0].column, targets[0]), lookup_type, raw_value), AND)
+ root_constraint.add(IsNull(Col(alias, targets[0], sources[0]), raw_value), AND)
elif (lookup_type == 'exact' or (lookup_type in ['gt', 'lt', 'gte', 'lte']
and not is_multicolumn)):
value = get_normalized_value(raw_value)
- for index, source in enumerate(sources):
+ for target, source, val in zip(targets, sources, value):
+ lookup_class = target.get_lookup(lookup_type)
root_constraint.add(
- (Constraint(alias, targets[index].column, sources[index]), lookup_type,
- value[index]), AND)
+ lookup_class(Col(alias, target, source), val), AND)
elif lookup_type in ['range', 'in'] and not is_multicolumn:
values = [get_normalized_value(value) for value in raw_value]
value = [val[0] for val in values]
- root_constraint.add(
- (Constraint(alias, targets[0].column, sources[0]), lookup_type, value), AND)
+ lookup_class = targets[0].get_lookup(lookup_type)
+ root_constraint.add(lookup_class(Col(alias, targets[0], sources[0]), value), AND)
elif lookup_type == 'in':
values = [get_normalized_value(value) for value in raw_value]
for value in values:
value_constraint = constraint_class()
- for index, target in enumerate(targets):
- value_constraint.add(
- (Constraint(alias, target.column, sources[index]), 'exact', value[index]),
- AND)
+ for source, target, val in zip(sources, targets, value):
+ lookup_class = target.get_lookup('exact')
+ lookup = lookup_class(Col(alias, target, source), val)
+ value_constraint.add(lookup, AND)
root_constraint.add(value_constraint, OR)
else:
raise TypeError('Related Field got invalid lookup: %s' % lookup_type)
View
317 django/db/models/lookups.py
@@ -0,0 +1,317 @@
+from copy import copy
+import inspect
+
+from django.conf import settings
+from django.utils import timezone
+from django.utils.functional import cached_property
+
+
+class RegisterLookupMixin(object):
+ def get_lookup(self, lookup_name):
+ try:
+ return self.class_lookups[lookup_name]
+ except KeyError:
+ # To allow for inheritance, check parent class class lookups.
+ for parent in inspect.getmro(self.__class__):
+ if not 'class_lookups' in parent.__dict__:
+ continue
+ if lookup_name in parent.class_lookups:
+ return parent.class_lookups[lookup_name]
+ except AttributeError:
+ # This class didn't have any class_lookups
+ pass
+ if hasattr(self, 'output_type'):
+ return self.output_type.get_lookup(lookup_name)
+ return None
+
+ @classmethod
+ def register_lookup(cls, lookup):
+ if not 'class_lookups' in cls.__dict__:
+ cls.class_lookups = {}
+ cls.class_lookups[lookup.lookup_name] = lookup
+
+ @classmethod
+ def _unregister_lookup(cls, lookup):
+ """
+ Removes given lookup from cls lookups. Meant to be used in
+ tests only.
+ """
+ del cls.class_lookups[lookup.lookup_name]
+
+
+class Transform(RegisterLookupMixin):
+ def __init__(self, lhs, lookups):
+ self.lhs = lhs
+ self.init_lookups = lookups[:]
+
+ def as_sql(self, qn, connection):
+ raise NotImplementedError
+
+ @cached_property
+ def output_type(self):
+ return self.lhs.output_type
+
+ def relabeled_clone(self, relabels):
+ return self.__class__(self.lhs.relabeled_clone(relabels))
+
+ def get_group_by_cols(self):
+ return self.lhs.get_group_by_cols()
+
+
+class Lookup(RegisterLookupMixin):
+ lookup_name = None
+
+ def __init__(self, lhs, rhs):
+ self.lhs, self.rhs = lhs, rhs
+ self.rhs = self.get_prep_lookup()
+
+ def get_prep_lookup(self):
+ return self.lhs.output_type.get_prep_lookup(self.lookup_name, self.rhs)
+
+ def get_db_prep_lookup(self, value, connection):
+ return (
+ '%s', self.lhs.output_type.get_db_prep_lookup(
+ self.lookup_name, value, connection, prepared=True))
+
+ def process_lhs(self, qn, connection, lhs=None):
+ lhs = lhs or self.lhs
+ return qn.compile(lhs)
+
+ def process_rhs(self, qn, connection, rhs=None):
+ value = rhs or self.rhs
+ # Due to historical reasons there are a couple of different
+ # ways to produce sql here. get_compiler is likely a Query
+ # instance, _as_sql QuerySet and as_sql just something with
+ # as_sql. Finally the value can of course be just plain
+ # Python value.
+ if hasattr(value, 'get_compiler'):
+ value = value.get_compiler(connection=connection)
+ if hasattr(value, 'as_sql'):
+ sql, params = qn.compile(value)
+ return '(' + sql + ')', params
+ if hasattr(value, '_as_sql'):
+ sql, params = value._as_sql(connection=connection)
+ return '(' + sql + ')', params
+ else:
+ return self.get_db_prep_lookup(value, connection)
+
+ def relabeled_clone(self, relabels):
+ new = copy(self)
+ new.lhs = new.lhs.relabeled_clone(relabels)
+ if hasattr(new.rhs, 'relabeled_clone'):
+ new.rhs = new.rhs.relabeled_clone(relabels)
+ return new
+
+ def get_group_by_cols(self):
+ cols = self.lhs.get_group_by_cols()
+ if hasattr(self.rhs, 'get_group_by_cols'):
+ cols.extend(self.rhs.get_group_by_cols())
+ return cols
+
+ def as_sql(self, qn, connection):
+ raise NotImplementedError
+
+
+class BuiltinLookup(Lookup):
+ def as_sql(self, qn, connection):
+ lhs_sql, params = self.process_lhs(qn, connection)
+ field_internal_type = self.lhs.output_type.get_internal_type()
+ db_type = self.lhs.output_type
+ lhs_sql = connection.ops.field_cast_sql(db_type, field_internal_type) % lhs_sql
+ lhs_sql = connection.ops.lookup_cast(self.lookup_name) % lhs_sql
+ rhs_sql, rhs_params = self.process_rhs(qn, connection)
+ params.extend(rhs_params)
+ operator_plus_rhs = self.get_rhs_op(connection, rhs_sql)
+ return '%s %s' % (lhs_sql, operator_plus_rhs), params
+
+ def get_rhs_op(self, connection, rhs):
+ return connection.operators[self.lookup_name] % rhs
+
+
+default_lookups = {}
+
+
+class Exact(BuiltinLookup):
+ lookup_name = 'exact'
+default_lookups['exact'] = Exact
+
+
+class IExact(BuiltinLookup):
+ lookup_name = 'iexact'
+default_lookups['iexact'] = IExact
+
+
+class Contains(BuiltinLookup):
+ lookup_name = 'contains'
+default_lookups['contains'] = Contains
+
+
+class IContains(BuiltinLookup):
+ lookup_name = 'icontains'
+default_lookups['icontains'] = IContains
+
+
+class GreaterThan(BuiltinLookup):
+ lookup_name = 'gt'
+default_lookups['gt'] = GreaterThan
+
+
+class GreaterThanOrEqual(BuiltinLookup):
+ lookup_name = 'gte'
+default_lookups['gte'] = GreaterThanOrEqual
+
+
+class LessThan(BuiltinLookup):
+ lookup_name = 'lt'
+default_lookups['lt'] = LessThan
+
+
+class LessThanOrEqual(BuiltinLookup):
+ lookup_name = 'lte'
+default_lookups['lte'] = LessThanOrEqual
+
+
+class In(BuiltinLookup):
+ lookup_name = 'in'
+
+ def get_db_prep_lookup(self, value, connection):
+ params = self.lhs.output_type.get_db_prep_lookup(
+ self.lookup_name, value, connection, prepared=True)
+ if not params:
+ # TODO: check why this leads to circular import
+ from django.db.models.sql.datastructures import EmptyResultSet
+ raise EmptyResultSet
+ placeholder = '(' + ', '.join('%s' for p in params) + ')'
+ return (placeholder, params)
+
+ def get_rhs_op(self, connection, rhs):
+ return 'IN %s' % rhs
+default_lookups['in'] = In
+
+
+class PatternLookup(BuiltinLookup):
+ def get_rhs_op(self, connection, rhs):
+ # Assume we are in startswith. We need to produce SQL like:
+ # col LIKE %s, ['thevalue%']
+ # For python values we can (and should) do that directly in Python,
+ # but if the value is for example reference to other column, then
+ # we need to add the % pattern match to the lookup by something like
+ # col LIKE othercol || '%%'
+ # So, for Python values we don't need any special pattern, but for
+ # SQL reference values we need the correct pattern added.
+ value = self.rhs
+ if (hasattr(value, 'get_compiler') or hasattr(value, 'as_sql')
+ or hasattr(value, '_as_sql')):
+ return connection.pattern_ops[self.lookup_name] % rhs
+ else:
+ return super(PatternLookup, self).get_rhs_op(connection, rhs)
+
+
+class StartsWith(PatternLookup):
+ lookup_name = 'startswith'
+default_lookups['startswith'] = StartsWith
+
+
+class IStartsWith(PatternLookup):
+ lookup_name = 'istartswith'
+default_lookups['istartswith'] = IStartsWith
+
+
+class EndsWith(BuiltinLookup):
+ lookup_name = 'endswith'
+default_lookups['endswith'] = EndsWith
+
+
+class IEndsWith(BuiltinLookup):
+ lookup_name = 'iendswith'
+default_lookups['iendswith'] = IEndsWith
+
+
+class Between(BuiltinLookup):
+ def get_rhs_op(self, connection, rhs):
+ return "BETWEEN %s AND %s" % (rhs, rhs)
+
+
+class Year(Between):
+ lookup_name = 'year'
+default_lookups['year'] = Year
+
+
+class Range(Between):
+ lookup_name = 'range'
+default_lookups['range'] = Range
+
+
+class DateLookup(BuiltinLookup):
+
+ def process_lhs(self, qn, connection):
+ lhs, params = super(DateLookup, self).process_lhs(qn, connection)
+ tzname = timezone.get_current_timezone_name() if settings.USE_TZ else None
+ sql, tz_params = connection.ops.datetime_extract_sql(self.extract_type, lhs, tzname)
+ return connection.ops.lookup_cast(self.lookup_name) % sql, tz_params
+
+ def get_rhs_op(self, connection, rhs):
+ return '= %s' % rhs
+
+
+class Month(DateLookup):
+ lookup_name = 'month'
+ extract_type = 'month'
+default_lookups['month'] = Month
+
+
+class Day(DateLookup):
+ lookup_name = 'day'
+ extract_type = 'day'
+default_lookups['day'] = Day
+
+
+class WeekDay(DateLookup):
+ lookup_name = 'week_day'
+ extract_type = 'week_day'
+default_lookups['week_day'] = WeekDay
+
+
+class Hour(DateLookup):
+ lookup_name = 'hour'
+ extract_type = 'hour'
+default_lookups['hour'] = Hour
+
+
+class Minute(DateLookup):
+ lookup_name = 'minute'
+ extract_type = 'minute'
+default_lookups['minute'] = Minute
+
+
+class Second(DateLookup):
+ lookup_name = 'second'
+ extract_type = 'second'
+default_lookups['second'] = Second
+
+
+class IsNull(BuiltinLookup):
+ lookup_name = 'isnull'
+
+ def as_sql(self, qn, connection):
+ sql, params = qn.compile(self.lhs)
+ if self.rhs:
+ return "%s IS NULL" % sql, params
+ else:
+ return "%s IS NOT NULL" % sql, params
+default_lookups['isnull'] = IsNull
+
+
+class Search(BuiltinLookup):
+ lookup_name = 'search'
+default_lookups['search'] = Search
+
+
+class Regex(BuiltinLookup):
+ lookup_name = 'regex'
+default_lookups['regex'] = Regex
+
+
+class IRegex(BuiltinLookup):
+ lookup_name = 'iregex'
+default_lookups['iregex'] = IRegex
View
10 django/db/models/sql/aggregates.py
@@ -4,6 +4,7 @@
import copy
from django.db.models.fields import IntegerField, FloatField
+from django.db.models.lookups import RegisterLookupMixin
__all__ = ['Aggregate', 'Avg', 'Count', 'Max', 'Min', 'StdDev', 'Sum', 'Variance']
@@ -14,7 +15,7 @@
computed_aggregate_field = FloatField()
-class Aggregate(object):
+class Aggregate(RegisterLookupMixin):
"""
Default SQL Aggregate.
"""
@@ -93,6 +94,13 @@ def as_sql(self, qn, connection):
return self.sql_template % substitutions, params
+ def get_group_by_cols(self):
+ return []
+
+ @property
+ def output_type(self):
+ return self.field
+
class Avg(Aggregate):
is_computed = True
View
63 django/db/models/sql/compiler.py
@@ -45,7 +45,7 @@ def pre_sql_setup(self):
if self.query.select_related and not self.query.related_select_cols:
self.fill_related_selections()
- def quote_name_unless_alias(self, name):
+ def __call__(self, name):
"""
A wrapper around connection.ops.quote_name that doesn't quote aliases
for table names. This avoids problems with some SQL dialects that treat
@@ -61,6 +61,22 @@ def quote_name_unless_alias(self, name):
self.quote_cache[name] = r
return r
+ def quote_name_unless_alias(self, name):
+ """
+ A wrapper around connection.ops.quote_name that doesn't quote aliases
+ for table names. This avoids problems with some SQL dialects that treat
+ quoted strings specially (e.g. PostgreSQL).
+ """
+ return self(name)
+
+ def compile(self, node):
+ vendor_impl = getattr(
+ node, 'as_' + self.connection.vendor, None)
+ if vendor_impl:
+ return vendor_impl(self, self.connection)
+ else:
+ return node.as_sql(self, self.connection)
+
def as_sql(self, with_limits=True, with_col_aliases=False):
"""
Creates the SQL for this query. Returns the SQL string and list of
@@ -88,11 +104,9 @@ def as_sql(self, with_limits=True, with_col_aliases=False):
# docstring of get_from_clause() for details.
from_, f_params = self.get_from_clause()
- qn = self.quote_name_unless_alias
-
- where, w_params = self.query.where.as_sql(qn=qn, connection=self.connection)
- having, h_params = self.query.having.as_sql(qn=qn, connection=self.connection)
- having_group_by = self.query.having.get_cols()
+ where, w_params = self.compile(self.query.where)
+ having, h_params = self.compile(self.query.having)
+ having_group_by = self.query.having.get_group_by_cols()
params = []
for val in six.itervalues(self.query.extra_select):
params.extend(val[1])
@@ -180,7 +194,7 @@ def get_columns(self, with_aliases=False):
(without the table names) are given unique aliases. This is needed in
some cases to avoid ambiguity with nested queries.
"""
- qn = self.quote_name_unless_alias
+ qn = self
qn2 = self.connection.ops.quote_name
result = ['(%s) AS %s' % (col[0], qn2(alias)) for alias, col in six.iteritems(self.query.extra_select)]
params = []
@@ -213,7 +227,7 @@ def get_columns(self, with_aliases=False):
aliases.add(r)
col_aliases.add(col[1])
else:
- col_sql, col_params = col.as_sql(qn, self.connection)
+ col_sql, col_params = self.compile(col)
result.append(col_sql)
params.extend(col_params)
@@ -229,7 +243,7 @@ def get_columns(self, with_aliases=False):
max_name_length = self.connection.ops.max_name_length()
for alias, aggregate in self.query.aggregate_select.items():
- agg_sql, agg_params = aggregate.as_sql(qn, self.connection)
+ agg_sql, agg_params = self.compile(aggregate)
if alias is None:
result.append(agg_sql)
else:
@@ -267,7 +281,7 @@ def get_default_columns(self, with_aliases=False, col_aliases=None,
result = []
if opts is None:
opts = self.query.get_meta()
- qn = self.quote_name_unless_alias
+ qn = self
qn2 = self.connection.ops.quote_name
aliases = set()
only_load = self.deferred_to_columns()
@@ -319,7 +333,7 @@ def get_distinct(self):
Note that this method can alter the tables in the query, and thus it
must be called before get_from_clause().
"""
- qn = self.quote_name_unless_alias
+ qn = self
qn2 = self.connection.ops.quote_name
result = []
opts = self.query.get_meta()
@@ -352,7 +366,7 @@ def get_ordering(self):
ordering = (self.query.order_by
or self.query.get_meta().ordering
or [])
- qn = self.quote_name_unless_alias
+ qn = self
qn2 = self.connection.ops.quote_name
distinct = self.query.distinct
select_aliases = self._select_aliases
@@ -490,7 +504,7 @@ def get_from_clause(self):
ordering and distinct must be done first.
"""
result = []
- qn = self.quote_name_unless_alias
+ qn = self
qn2 = self.connection.ops.quote_name
first = True
from_params = []
@@ -508,8 +522,7 @@ def get_from_clause(self):
extra_cond = join_field.get_extra_restriction(
self.query.where_class, alias, lhs)
if extra_cond:
- extra_sql, extra_params = extra_cond.as_sql(
- qn, self.connection)
+ extra_sql, extra_params = self.compile(extra_cond)
extra_sql = 'AND (%s)' % extra_sql
from_params.extend(extra_params)
else:
@@ -541,7 +554,7 @@ def get_grouping(self, having_group_by, ordering_group_by):
"""
Returns a tuple representing the SQL elements in the "group by" clause.
"""
- qn = self.quote_name_unless_alias
+ qn = self
result, params = [], []
if self.query.group_by is not None:
select_cols = self.query.select + self.query.related_select_cols
@@ -560,7 +573,7 @@ def get_grouping(self, having_group_by, ordering_group_by):
if isinstance(col, (list, tuple)):
sql = '%s.%s' % (qn(col[0]), qn(col[1]))
elif hasattr(col, 'as_sql'):
- sql, col_params = col.as_sql(qn, self.connection)
+ self.compile(col)
else:
sql = '(%s)' % str(col)
if sql not in seen:
@@ -784,7 +797,7 @@ def execute_sql(self, result_type=MULTI):
return result
def as_subquery_condition(self, alias, columns, qn):
- inner_qn = self.quote_name_unless_alias
+ inner_qn = self
qn2 = self.connection.ops.quote_name
if len(columns) == 1:
sql, params = self.as_sql()
@@ -895,9 +908,9 @@ def as_sql(self):
"""
assert len(self.query.tables) == 1, \
"Can only delete from one table at a time."
- qn = self.quote_name_unless_alias
+ qn = self
result = ['DELETE FROM %s' % qn(self.query.tables[0])]
- where, params = self.query.where.as_sql(qn=qn, connection=self.connection)
+ where, params = self.compile(self.query.where)
if where:
result.append('WHERE %s' % where)
return ' '.join(result), tuple(params)
@@ -913,7 +926,7 @@ def as_sql(self):
if not self.query.values:
return '', ()
table = self.query.tables[0]
- qn = self.quote_name_unless_alias
+ qn = self
result = ['UPDATE %s' % qn(table)]
result.append('SET')
values, update_params = [], []
@@ -933,7 +946,7 @@ def as_sql(self):
val = SQLEvaluator(val, self.query, allow_joins=False)
name = field.column
if hasattr(val, 'as_sql'):
- sql, params = val.as_sql(qn, self.connection)
+ sql, params = self.compile(val)
values.append('%s = %s' % (qn(name), sql))
update_params.extend(params)
elif val is not None:
@@ -944,7 +957,7 @@ def as_sql(self):
if not values:
return '', ()
result.append(', '.join(values))
- where, params = self.query.where.as_sql(qn=qn, connection=self.connection)
+ where, params = self.compile(self.query.where)
if where:
result.append('WHERE %s' % where)
return ' '.join(result), tuple(update_params + params)
@@ -1024,11 +1037,11 @@ def as_sql(self, qn=None):
parameters.
"""
if qn is None:
- qn = self.quote_name_unless_alias
+ qn = self
sql, params = [], []
for aggregate in self.query.aggregate_select.values():
- agg_sql, agg_params = aggregate.as_sql(qn, self.connection)
+ agg_sql, agg_params = self.compile(aggregate)
sql.append(agg_sql)
params.extend(agg_params)
sql = ', '.join(sql)
View
23 django/db/models/sql/datastructures.py
@@ -5,18 +5,27 @@
class Col(object):
- def __init__(self, alias, col):
- self.alias = alias
- self.col = col
+ def __init__(self, alias, target, source):
+ self.alias, self.target, self.source = alias, target, source
def as_sql(self, qn, connection):
- return '%s.%s' % (qn(self.alias), self.col), []
+ return "%s.%s" % (qn(self.alias), qn(self.target.column)), []
- def prepare(self):
- return self
+ @property
+ def output_type(self):
+ return self.source
def relabeled_clone(self, relabels):
- return self.__class__(relabels.get(self.alias, self.alias), self.col)
+ return self.__class__(relabels.get(self.alias, self.alias), self.target, self.source)
+
+ def get_group_by_cols(self):
+ return [(self.alias, self.target.column)]
+
+ def get_lookup(self, name):
+ return self.output_type.get_lookup(name)
+
+ def prepare(self):
+ return self
class EmptyResultSet(Exception):
View
6 django/db/models/sql/expressions.py
@@ -24,11 +24,11 @@ def relabeled_clone(self, change_map):
(change_map.get(col[0], col[0]), col[1])))
return clone
- def get_cols(self):
+ def get_group_by_cols(self):
cols = []
for node, col in self.cols:
- if hasattr(node, 'get_cols'):
- cols.extend(node.get_cols())
+ if hasattr(node, 'get_group_by_cols'):
+ cols.extend(node.get_group_by_cols())
elif isinstance(col, tuple):
cols.append(col)
return cols
View
179 django/db/models/sql/query.py
@@ -19,6 +19,7 @@
from django.db.models.aggregates import refs_aggregate
from django.db.models.expressions import ExpressionNode
from django.db.models.fields import FieldDoesNotExist
+from django.db.models.lookups import Transform
from django.db.models.query_utils import Q
from django.db.models.related import PathInfo
from django.db.models.sql import aggregates as base_aggregates_module
@@ -1028,13 +1029,16 @@ def add_aggregate(self, aggregate, model, alias, is_summary):
# Add the aggregate to the query
aggregate.add_to_query(self, alias, col=col, source=source, is_summary=is_summary)
- def prepare_lookup_value(self, value, lookup_type, can_reuse):
+ def prepare_lookup_value(self, value, lookups, can_reuse):
+ # Default lookup if none given is exact.
+ if len(lookups) == 0:
+ lookups = ['exact']
# Interpret '__exact=None' as the sql 'is NULL'; otherwise, reject all
# uses of None as a query value.
if value is None:
- if lookup_type not in ('exact', 'iexact'):
+ if lookups[-1] not in ('exact', 'iexact'):
raise ValueError("Cannot use None as a query value")
- lookup_type = 'isnull'
+ lookups[-1] = 'isnull'
value = True
elif callable(value):
warnings.warn(
@@ -1055,40 +1059,54 @@ def prepare_lookup_value(self, value, lookup_type, can_reuse):
# stage. Using DEFAULT_DB_ALIAS isn't nice, but it is the best we
# can do here. Similar thing is done in is_nullable(), too.
if (connections[DEFAULT_DB_ALIAS].features.interprets_empty_strings_as_nulls and
- lookup_type == 'exact' and value == ''):
+ lookups[-1] == 'exact' and value == ''):
value = True
- lookup_type = 'isnull'
- return value, lookup_type
+ lookups[-1] = ['isnull']
+ return value, lookups
def solve_lookup_type(self, lookup):
"""
Solve the lookup type from the lookup (eg: 'foobar__id__icontains')
"""
- lookup_type = 'exact' # Default lookup type
- lookup_parts = lookup.split(LOOKUP_SEP)
- num_parts = len(lookup_parts)
- if (len(lookup_parts) > 1 and lookup_parts[-1] in self.query_terms
- and (not self._aggregates or lookup not in self._aggregates)):
- # Traverse the lookup query to distinguish related fields from
- # lookup types.
- lookup_model = self.model
- for counter, field_name in enumerate(lookup_parts):
- try:
- lookup_field = lookup_model._meta.get_field(field_name)
- except FieldDoesNotExist:
- # Not a field. Bail out.
- lookup_type = lookup_parts.pop()
- break
- # Unless we're at the end of the list of lookups, let's attempt
- # to continue traversing relations.
- if (counter + 1) < num_parts:
- try:
- lookup_model = lookup_field.rel.to
- except AttributeError:
- # Not a related field. Bail out.
- lookup_type = lookup_parts.pop()
- break
- return lookup_type, lookup_parts
+ lookup_splitted = lookup.split(LOOKUP_SEP)
+ if self._aggregates:
+ aggregate, aggregate_lookups = refs_aggregate(lookup_splitted, self.aggregates)
+ if aggregate:
+ return aggregate_lookups, (), aggregate
+ _, field, _, lookup_parts = self.names_to_path(lookup_splitted, self.get_meta())
+ field_parts = lookup_splitted[0:len(lookup_splitted) - len(lookup_parts)]
+ if len(lookup_parts) == 0:
+ lookup_parts = ['exact']
+ elif len(lookup_parts) > 1:
+ if not field_parts:
+ raise FieldError(
+ 'Invalid lookup "%s" for model %s".' %
+ (lookup, self.get_meta().model.__name__))
+ return lookup_parts, field_parts, False
+
+ def build_lookup(self, lookups, lhs, rhs):
+ lookups = lookups[:]
+ while lookups:
+ lookup = lookups[0]
+ next = lhs.get_lookup(lookup)
+ if next:
+ if len(lookups) == 1:
+ # This was the last lookup, so return value lookup.
+ if issubclass(next, Transform):
+ lookups.append('exact')
+ lhs = next(lhs, lookups)
+ else:
+ return next(lhs, rhs)
+ else:
+ lhs = next(lhs, lookups)
+ # A field's get_lookup() can return None to opt for backwards
+ # compatibility path.
+ elif len(lookups) > 2:
+ raise FieldError(
+ "Unsupported lookup for field '%s'" % lhs.output_type.name)
+ else:
+ return None
+ lookups = lookups[1:]
def build_filter(self, filter_expr, branch_negated=False, current_negated=False,
can_reuse=None, connector=AND):
@@ -1118,21 +1136,24 @@ def build_filter(self, filter_expr, branch_negated=False, current_negated=False,
is responsible for unreffing the joins used.
"""
arg, value = filter_expr
- lookup_type, parts = self.solve_lookup_type(arg)
- if not parts:
+ if not arg:
raise FieldError("Cannot parse keyword query %r" % arg)
+ lookups, parts, reffed_aggregate = self.solve_lookup_type(arg)
# Work out the lookup type and remove it from the end of 'parts',
# if necessary.
- value, lookup_type = self.prepare_lookup_value(value, lookup_type, can_reuse)
+ value, lookups = self.prepare_lookup_value(value, lookups, can_reuse)
used_joins = getattr(value, '_used_joins', [])
clause = self.where_class()
- if self._aggregates:
- for alias, aggregate in self.aggregates.items():
- if alias in (parts[0], LOOKUP_SEP.join(parts)):
- clause.add((aggregate, lookup_type, value), AND)
- return clause, []
+ if reffed_aggregate:
+ condition = self.build_lookup(lookups, reffed_aggregate, value)
+ if not condition:
+ # Backwards compat for custom lookups
+ assert len(lookups) == 1
+ condition = (reffed_aggregate, lookups[0], value)
+ clause.add(condition, AND)
+ return clause, []
opts = self.get_meta()
alias = self.get_initial_alias()
@@ -1154,11 +1175,31 @@ def build_filter(self, filter_expr, branch_negated=False, current_negated=False,
targets, alias, join_list = self.trim_joins(sources, join_list, path)
if hasattr(field, 'get_lookup_constraint'):
- constraint = field.get_lookup_constraint(self.where_class, alias, targets, sources,
- lookup_type, value)
+ # For now foreign keys get special treatment. This should be
+ # refactored when composite fields lands.
+ condition = field.get_lookup_constraint(self.where_class, alias, targets, sources,
+ lookups, value)
+ lookup_type = lookups[-1]
else:
- constraint = (Constraint(alias, targets[0].column, field), lookup_type, value)
- clause.add(constraint, AND)
+ assert(len(targets) == 1)
+ col = Col(alias, targets[0], field)
+ condition = self.build_lookup(lookups, col, value)
+ if not condition:
+ # Backwards compat for custom lookups
+ if lookups[0] not in self.query_terms:
+ raise FieldError(
+ "Join on field '%s' not permitted. Did you "
+ "misspell '%s' for the lookup type?" %
+ (col.output_type.name, lookups[0]))
+ if len(lookups) > 1:
+ raise FieldError("Nested lookup '%s' not supported." %
+ LOOKUP_SEP.join(lookups))
+ condition = (Constraint(alias, targets[0].column, field), lookups[0], value)
+ lookup_type = lookups[-1]
+ else:
+ lookup_type = condition.lookup_name
+
+ clause.add(condition, AND)
require_outer = lookup_type == 'isnull' and value is True and not current_negated
if current_negated and (lookup_type != 'isnull' or value is False):
@@ -1175,7 +1216,8 @@ def build_filter(self, filter_expr, branch_negated=False, current_negated=False,
# (col IS NULL OR col != someval)
# <=>
# NOT (col IS NOT NULL AND col = someval).
- clause.add((Constraint(alias, targets[0].column, None), 'isnull', False), AND)
+ lookup_class = targets[0].get_lookup('isnull')
+ clause.add(lookup_class(Col(alias, targets[0], sources[0]), False), AND)
return clause, used_joins if not require_outer else ()
def add_filter(self, filter_clause):
@@ -1189,7 +1231,7 @@ def need_having(self, obj):
if not self._aggregates:
return False
if not isinstance(obj, Node):
- return (refs_aggregate(obj[0].split(LOOKUP_SEP), self.aggregates)
+ return (refs_aggregate(obj[0].split(LOOKUP_SEP), self.aggregates)[0]
or (hasattr(obj[1], 'contains_aggregate')
and obj[1].contains_aggregate(self.aggregates)))
return any(self.need_having(c) for c in obj.children)
@@ -1277,7 +1319,7 @@ def _add_q(self, q_object, used_aliases, branch_negated=False,
needed_inner = joinpromoter.update_join_types(self)
return target_clause, needed_inner
- def names_to_path(self, names, opts, allow_many):
+ def names_to_path(self, names, opts, allow_many=True, fail_on_missing=False):
"""
Walks the names path and turns them PathInfo tuples. Note that a
single name in 'names' can generate multiple PathInfos (m2m for
@@ -1297,9 +1339,10 @@ def names_to_path(self, names, opts, allow_many):
try:
field, model, direct, m2m = opts.get_field_by_name(name)
except FieldDoesNotExist:
- available = opts.get_all_field_names() + list(self.aggregate_select)
- raise FieldError("Cannot resolve keyword %r into field. "
- "Choices are: %s" % (name, ", ".join(available)))
+ # We didn't found the current field, so move position back
+ # one step.
+ pos -= 1
+ break
# Check if we need any joins for concrete inheritance cases (the
# field lives in parent, but we are currently in one of its
# children)
@@ -1334,15 +1377,14 @@ def names_to_path(self, names, opts, allow_many):
final_field = field
targets = (field,)
break
+ if pos == -1 or (fail_on_missing and pos + 1 != len(names)):
+ self.raise_field_error(opts, name)
+ return path, final_field, targets, names[pos + 1:]
- if pos != len(names) - 1:
- if pos == len(names) - 2:
- raise FieldError(
- "Join on field %r not permitted. Did you misspell %r for "
- "the lookup type?" % (name, names[pos + 1]))
- else:
- raise FieldError("Join on field %r not permitted." % name)
- return path, final_field, targets
+ def raise_field_error(self, opts, name):
+ available = opts.get_all_field_names() + list(self.aggregate_select)
+ raise FieldError("Cannot resolve keyword %r into field. "
+ "Choices are: %s" % (name, ", ".join(available)))
def setup_joins(self, names, opts, alias, can_reuse=None, allow_many=True):
"""
@@ -1371,8 +1413,9 @@ def setup_joins(self, names, opts, alias, can_reuse=None, allow_many=True):
"""
joins = [alias]
# First, generate the path for the names
- path, final_field, targets = self.names_to_path(
- names, opts, allow_many)
+ path, final_field, targets, rest = self.names_to_path(
+ names, opts, allow_many, fail_on_missing=True)
+
# Then, add the path to the query's joins. Note that we can't trim
# joins at this stage - we will need the information about join type
# of the trimmed joins.
@@ -1387,8 +1430,6 @@ def setup_joins(self, names, opts, alias, can_reuse=None, allow_many=True):
alias = self.join(
connection, reuse=reuse, nullable=nullable, join_field=join.join_field)
joins.append(alias)
- if hasattr(final_field, 'field'):
- final_field = final_field.field
return final_field, targets, opts, joins, path
def trim_joins(self, targets, joins, path):
@@ -1451,17 +1492,19 @@ def split_exclude(self, filter_expr, prefix, can_reuse, names_with_path):
# nothing
alias, col = query.select[0].col
if self.is_nullable(query.select[0].field):
- query.where.add((Constraint(alias, col, query.select[0].field), 'isnull', False), AND)
+ lookup_class = query.select[0].field.get_lookup('isnull')
+ lookup = lookup_class(Col(alias, query.select[0].field, query.select[0].field), False)
+ query.where.add(lookup, AND)
if alias in can_reuse:
- pk = query.select[0].field.model._meta.pk
+ select_field = query.select[0].field
+ pk = select_field.model._meta.pk
# Need to add a restriction so that outer query's filters are in effect for
# the subquery, too.
query.bump_prefix(self)
- query.where.add(
- (Constraint(query.select[0].col[0], pk.column, pk),
- 'exact', Col(alias, pk.column)),
- AND
- )
+ lookup_class = select_field.get_lookup('exact')
+ lookup = lookup_class(Col(query.select[0].col[0], pk, pk),
+ Col(alias, pk, pk))
+ query.where.add(lookup, AND)
condition, needed_inner = self.build_filter(
('%s__in' % trimmed_prefix, query),
View
20 django/db/models/sql/subqueries.py
@@ -5,12 +5,12 @@
from django.conf import settings
from django.core.exceptions import FieldError
from django.db import connections
+from django.db.models.query_utils import Q
from django.db.models.constants import LOOKUP_SEP
from django.db.models.fields import DateField, DateTimeField, FieldDoesNotExist
from django.db.models.sql.constants import GET_ITERATOR_CHUNK_SIZE, SelectInfo
from django.db.models.sql.datastructures import Date, DateTime
from django.db.models.sql.query import Query
-from django.db.models.sql.where import AND, Constraint
from django.utils import six
from django.utils import timezone
@@ -42,10 +42,10 @@ def delete_batch(self, pk_list, using, field=None):
if not field:
field = self.get_meta().pk
for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
- where = self.where_class()
- where.add((Constraint(None, field.column, field), 'in',
- pk_list[offset:offset + GET_ITERATOR_CHUNK_SIZE]), AND)
- self.do_query(self.get_meta().db_table, where, using=using)
+ self.where = self.where_class()
+ self.add_q(Q(
+ **{field.attname + '__in': pk_list[offset:offset + GET_ITERATOR_CHUNK_SIZE]}))
+ self.do_query(self.get_meta().db_table, self.where, using=using)
def delete_qs(self, query, using):
"""
@@ -80,9 +80,8 @@ def delete_qs(self, query, using):
SelectInfo((self.get_initial_alias(), pk.column), None)
]
values = innerq
- where = self.where_class()
- where.add((Constraint(None, pk.column, pk), 'in', values), AND)
- self.where = where
+ self.where = self.where_class()
+ self.add_q(Q(pk__in=values))
self.get_compiler(using).execute_sql(None)
@@ -113,13 +112,10 @@ def clone(self, klass=None, **kwargs):
related_updates=self.related_updates.copy(), **kwargs)
def update_batch(self, pk_list, values, using):
- pk_field = self.get_meta().pk
self.add_update_values(values)
for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
self.where = self.where_class()
- self.where.add((Constraint(None, pk_field.column, pk_field), 'in',
- pk_list[offset:offset + GET_ITERATOR_CHUNK_SIZE]),
- AND)
+ self.add_q(Q(pk__in=pk_list[offset: offset + GET_ITERATOR_CHUNK_SIZE]))
self.get_compiler(using).execute_sql(None)
def add_update_values(self, values):
View
27 django/db/models/sql/where.py
@@ -5,6 +5,7 @@
import collections
import datetime
from itertools import repeat
+import warnings
from django.conf import settings
from django.db.models.fields import DateTimeField, Field
@@ -101,7 +102,7 @@ def as_sql(self, qn, connection):
for child in self.children:
try:
if hasattr(child, 'as_sql'):
- sql, params = child.as_sql(qn=qn, connection=connection)
+ sql, params = qn.compile(child)
else:
# A leaf node in the tree.
sql, params = self.make_atom(child, qn, connection)
@@ -152,16 +153,16 @@ def as_sql(self, qn, connection):
sql_string = '(%s)' % sql_string
return sql_string, result_params
- def get_cols(self):
+ def get_group_by_cols(self):
cols = []
for child in self.children:
- if hasattr(child, 'get_cols'):
- cols.extend(child.get_cols())
+ if hasattr(child, 'get_group_by_cols'):
+ cols.extend(child.get_group_by_cols())
else:
if isinstance(child[0], Constraint):
cols.append((child[0].alias, child[0].col))
- if hasattr(child[3], 'get_cols'):
- cols.extend(child[3].get_cols())
+ if hasattr(child[3], 'get_group_by_cols'):
+ cols.extend(child[3].get_group_by_cols())
return cols
def make_atom(self, child, qn, connection):
@@ -174,6 +175,9 @@ def make_atom(self, child, qn, connection):
Returns the string for the SQL fragment and the parameters to use for
it.
"""
+ warnings.warn(
+ "The make_atom() method will be removed in Django 1.9. Use Lookup class instead.",
+ PendingDeprecationWarning)
lvalue, lookup_type, value_annotation, params_or_value = child
field_internal_type = lvalue.field.get_internal_type() if lvalue.field else None
@@ -193,13 +197,13 @@ def make_atom(self, child, qn, connection):
field_sql, field_params = self.sql_for_columns(lvalue, qn, connection, field_internal_type), []
else:
# A smart object with an as_sql() method.
- field_sql, field_params = lvalue.as_sql(qn, connection)
+ field_sql, field_params = qn.compile(lvalue)
is_datetime_field = value_annotation is datetime.datetime
cast_sql = connection.ops.datetime_cast_sql() if is_datetime_field else '%s'
if hasattr(params, 'as_sql'):
- extra, params = params.as_sql(qn, connection)
+ extra, params = qn.compile(params)
cast_sql = ''
else:
extra = ''
@@ -282,6 +286,8 @@ def relabel_aliases(self, change_map):
if hasattr(child, 'relabel_aliases'):
# For example another WhereNode
child.relabel_aliases(change_map)
+ elif hasattr(child, 'relabeled_clone'):
+ self.children[pos] = child.relabeled_clone(change_map)
elif isinstance(child, (list, tuple)):
# tuple starting with Constraint
child = (child[0].relabeled_clone(change_map),) + child[1:]
@@ -347,10 +353,13 @@ class Constraint(object):
pre-process itself prior to including in the WhereNode.
"""
def __init__(self, alias, col, field):
+ warnings.warn(
+ "The Constraint class will be removed in Django 1.9. Use Lookup class instead.",
+ PendingDeprecationWarning)
self.alias, self.col, self.field = alias, col, field
def prepare(self, lookup_type, value):
- if self.field:
+ if self.field and not hasattr(value, 'as_sql'):
return self.field.get_prep_lookup(lookup_type, value)
return value
View
6 docs/howto/custom-model-fields.txt
@@ -662,6 +662,12 @@ Django filter lookups: ``exact``, ``iexact``, ``contains``, ``icontains``,
``endswith``, ``iendswith``, ``range``, ``year``, ``month``, ``day``,
``isnull``, ``search``, ``regex``, and ``iregex``.
+.. versionadded:: 1.7
+
+ If you are using :doc:`Custom lookups </ref/models/custom-lookups>` the
+ ``lookup_type`` can be any ``lookup_name`` used by the project's custom
+ lookups.
+
Your method must be prepared to handle all of these ``lookup_type`` values and
should raise either a ``ValueError`` if the ``value`` is of the wrong sort (a
list when you were expecting an object, for example) or a ``TypeError`` if
View
3  docs/index.txt
@@ -81,7 +81,8 @@ manipulating the data of your Web application. Learn more about it below:
:doc:`Transactions <topics/db/transactions>` |
:doc:`Aggregation <topics/db/aggregation>` |
:doc:`Custom fields <howto/custom-model-fields>` |
- :doc:`Multiple databases <topics/db/multi-db>`
+ :doc:`Multiple databases <topics/db/multi-db>` |
+ :doc:`Custom lookups <ref/models/custom-lookups>`
* **Other:**
:doc:`Supported databases <ref/databases>` |
View
336 docs/ref/models/custom-lookups.txt
@@ -0,0 +1,336 @@
+==============
+Custom lookups
+==============
+
+.. versionadded:: 1.7
+
+.. module:: django.db.models.lookups
+ :synopsis: Custom lookups
+
+.. currentmodule:: django.db.models
+
+By default Django offers a wide variety of :ref:`built-in lookups
+<field-lookups>` for filtering (for example, ``exact`` and ``icontains``). This
+documentation explains how to write custom lookups and how to alter the working
+of existing lookups.
+
+A simple Lookup example
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Let's start with a simple custom lookup. We will write a custom lookup ``ne``
+which works opposite to ``exact``. ``Author.objects.filter(name__ne='Jack')``
+will translate to the SQL::
+
+ "author"."name" <> 'Jack'
+
+This SQL is backend independent, so we don't need to worry about different
+databases.
+
+There are two steps to making this work. Firstly we need to implement the
+lookup, then we need to tell Django about it. The implementation is quite
+straightforward::
+
+ from django.db.models import Lookup
+
+ class NotEqual(Lookup):
+ lookup_name = 'ne'
+
+ def as_sql(self, qn, connection):
+ lhs, lhs_params = self.process_lhs(qn, connection)
+ rhs, rhs_params = self.process_rhs(qn, connection)
+ params = lhs_params + rhs_params
+ return '%s <> %s' % (lhs, rhs), params
+
+To register the ``NotEqual`` lookup we will just need to call
+``register_lookup`` on the field class we want the lookup to be available. In
+this case, the lookup makes sense on all ``Field`` subclasses, so we register
+it with ``Field`` directly::
+
+ from django.db.models.fields import Field
+ Field.register_lookup(NotEqual)
+
+We can now use ``foo__ne`` for any field ``foo``. You will need to ensure that
+this registration happens before you try to create any querysets using it. You
+could place the implementation in a ``models.py`` file, or register the lookup
+in the ``ready()`` method of an ``AppConfig``.
+
+Taking a closer look at the implementation, the first required attribute is
+``lookup_name``. This allows the ORM to understand how to interpret ``name__ne``
+and use ``NotEqual`` to generate the SQL. By convention, these names are always
+lowercase strings containing only letters, but the only hard requirement is
+that it must not contain the string ``__``.
+
+A ``Lookup`` works against two values, ``lhs`` and ``rhs``, standing for
+left-hand side and right-hand side. The left-hand side is usually a field
+reference, but it can be anything implementing the :ref:`query expression API
+<query-expression>`. The right-hand is the value given by the user. In the
+example ``Author.objects.filter(name__ne='Jack')``, the left-hand side is a
+reference to the ``name`` field of the ``Author`` model, and ``'Jack'`` is the
+right-hand side.
+
+We call ``process_lhs`` and ``process_rhs`` to convert them into the values we
+need for SQL. In the above example, ``process_lhs`` returns
+``('"author"."name"', [])`` and ``process_rhs`` returns ``('"%s"', ['Jack'])``.
+In this example there were no parameters for the left hand side, but this would
+depend on the object we have, so we still need to include them in the
+parameters we return.
+
+Finally we combine the parts into a SQL expression with ``<>``, and supply all
+the parameters for the query. We then return a tuple containing the generated
+SQL string and the parameters.
+
+A simple transformer example
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The custom lookup above is great, but in some cases you may want to be able to
+chain lookups together. For example, let's suppose we are building an
+application where we want to make use of the ``abs()`` operator.
+We have an ``Experiment`` model which records a start value, end value and the
+change (start - end). We would like to find all experiments where the change
+was equal to a certain amount (``Experiment.objects.filter(change__abs=27)``),
+or where it did not exceede a certain amount
@claudep Collaborator
claudep added a note

exceede -> exceed

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+(``Experiment.objects.filter(change__abs__lt=27)``).
+
+.. note::
+ This example is somewhat contrived, but it demonstrates nicely the range of
+ functionality which is possible in a database backend independent manner,
+ and without duplicating functionality already in Django.
+
+We will start by writing a ``AbsoluteValue`` transformer. This will use the SQL
+function ``ABS()`` to transform the value before comparison::
+
+ from django.db.models import Transform
+
+ class AbsoluteValue(Transform):
+ lookup_name = 'abs'
+
+ def as_sql(self, qn, connection):
+ lhs, params = qn.compile(self.lhs)
+ return "ABS(%s)" % lhs, params
+
+Next, lets register it for ``IntegerField``::
+
+ from django.db.models import IntegerField
+ IntegerField.register_lookup(AbsoluteValue)
+
+We can now run the queris we had before.
@claudep Collaborator
claudep added a note

query, or queries?

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+``Experiment.objects.filter(change__abs=27)`` will generate the following SQL::
+
+ SELECT ... WHERE ABS("experiments"."change") = 27
+
+By using ``Transform`` instead of ``Lookup`` it means we are able to chain
+further lookups afterwards. So
+``Experiment.objects.filter(change__abs__lt=27)`` will generate the following
+SQL::
+
+ SELECT ... WHERE ABS("experiments"."change") < 27
+
+Subclasses of ``Transform`` usually only operate on the left-hand side of the
+expression. Further lookups will work on the transformed value. Note that in
+this case where there is no other lookup specified, Django interprets
+``change__abs=27`` as ``change__abs__exact=27``.
+
+When looking for which lookups are allowable after the ``Transform`` has been
+applied, Django uses the ``output_type`` attribute. We didn't need to specify
+this here as it didn't change, but supposing we were applying ``AbsoluteValue``
+to some field which represents a more complex type (for example a point
+relative to an origin, or a complex number) then we may have wanted to specify
+``output_type = FloatField``, which will ensure that further lookups like
+``abs__lte`` behave as they would for a ``FloatField``.
+
+Writing an efficient abs__lt lookup
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When using the above written ``abs`` lookup, the SQL produced will not use
+indexes efficiently in some cases. In particular, when we use
+``change__abs__lt=27``, this is equivalent to ``change__gt=-27`` AND
+``change__lt=27``. (For the ``lte`` case we could use the SQL ``BETWEEN``).
+
+So we would like ``Experiment.objects.filter(change__abs__lt=27)`` to generate
+the following SQL::
+
+ SELECT .. WHERE "experiments"."change" < 27 AND "experiments"."change" > -27
+
+The implementation is::
+
+ from django.db.models import Lookup
+
+ class AbsoluteValueLessThan(Lookup):
+ lookup_name = 'lt'
+
+ def as_sql(self, qn, connection):
+ lhs, lhs_params = qn.compile(self.lhs.lhs)
+ rhs, rhs_params = self.process_rhs(qn, connection)
+ params = lhs_params + rhs_params + lhs_params + rhs_params
+ return '%s > %s AND %s < -%s % (lhs, rhs, lhs, rhs), params
+
+ AbsoluteValue.register_lookup(AbsoluteValueLessThan)
+
+There are a couple of notable things going on. First, ``AbsoluteValueLessThan``
+isn't calling ``process_lhs()``. Instead it skips the transformation of the
+``lhs`` done by ``AbsoluteValue`` and uses the original ``lhs``. That is, we
+want to get ``27`` not ``ABS(27)``. Referring directly to ``self.lhs.lhs`` is
+safe as ``AbsoluteValueLessThan`` can be accessed only from the
+``AbsoluteValue`` lookup, that is the ``lhs`` is always an instance of
+``AbsoluteValue``.
+
+Notice also that as both sides are used multiple times in the query the params
+need to contain ``lhs_params`` and ``rhs_params`` multiple times.
+
+The final query does the inversion (``27`` to ``-27``) directly in the
+database. The reason for doing this is that if the self.rhs is something else
+than a plain integer value (for example an ``F()`` reference) we can't do the
+transformations in Python.
+
+.. note::
+ In fact, most lookups with ``__abs`` could be implemented as range queries
+ like this, and on most database backend it is likely to be more sensible to
@claudep Collaborator
claudep added a note

backend missing 's'

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+ do so as you can make use of the indexes. However with PostgreSQL you may
+ want to add an index on ``abs(change)`` which would allow these queries to
+ be very efficient.
+
+Writing alternative implemenatations for existing lookups
@claudep Collaborator
claudep added a note

implemenatations -> implementations

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+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Sometimes different database vendors require different SQL for the same
+operation. For this example we will rewrite a custom implementation for
+MySQL for the NotEqual operator. Instead of ``<>`` we will be using ``!=``
+operator. (Note that in reality almost all databases support both, including
+all the official databases supported by Django).
+
+We can change the behaviour on a specific backend by creating a subclass of
+``NotEqual`` with a ``as_mysql`` method::
+
+ class MySQLNotEqual(NotEqual):
+ def as_mysql(self, qn, connection):
+ lhs, lhs_params = self.process_lhs(qn, connection)
+ rhs, rhs_params = self.process_rhs(qn, connection)
+ params = lhs_params + rhs_params
+ return '%s != %s' % (lhs, rhs), params
+ Field.register_lookup(MySQLNotExact)
+
+We can then register it with ``Field``. It takes the place of the original
+``NotEqual`` class as it has
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Unfinished sentence?

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+
+When compiling a query, Django first looks for ``as_%s % connection.vendor``
+methods, and then falls back to ``as_sql``. The vendor names for the in-built
+backends are ``sqlite``, ``postgresql``, ``oracle`` and ``mysql``.
+
+.. _query-expression:
+
+The Query Expression API
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+A lookup can assume that the lhs responds to the query expression API.
+Currently direct field references, aggregates and ``Transform`` instances respond
+to this API.
+
+.. method:: as_sql(qn, connection)
+
+ Responsible for producing the query string and parameters for the
+ expression. The ``qn`` has a ``compile()`` method that can be used to
+ compile other expressions. The ``connection`` is the connection used to
+ execute the query.
+
+ Calling expression.as_sql() directly is usually incorrect - instead
+ qn.compile(expression) should be used. The qn.compile() method will take
+ care of calling vendor-specific methods of the expression.
+
+.. method:: get_lookup(lookup_name)
+
+ The ``get_lookup()`` method is used to fetch lookups. By default the
+ lookup is fetched from the expression's output type in the same way
+ described in registering and fetching lookup documentation below.
+ It is possible to override this method to alter that behaviour.
+
+.. method:: as_vendorname(qn, connection)
+
+ Works like ``as_sql()`` method. When an expression is compiled by
+ ``qn.compile()``, Django will first try to call ``as_vendorname()``, where
+ vendorname is the vendor name of the backend used for executing the query.
+ The vendorname is one of ``postgresql``, ``oracle``, ``sqlite`` or
+ ``mysql`` for Django's built-in backends.
+
+.. attribute:: output_type
+
+ The ``output_type`` attribute is used by the ``get_lookup()`` method to check for
+ lookups. The output_type should be a field.
+
+Note that this documentation lists only the public methods of the API.
+
+Lookup reference
+~~~~~~~~~~~~~~~~
+
+.. class:: Lookup
+
+ In addition to the attributes and methods below, lookups also support
+ ``as_sql`` and ``as_vendorname`` from the query expression API.
+
+.. attribute:: lhs
+
+ The ``lhs`` (left-hand side) of a lookup tells us what we are comparing the
+ rhs to. It is an object which implements the query expression API. This is
+ likely to be a field, an aggregate or a subclass of ``Transform``.
+
+.. attribute:: rhs
+
+ The ``rhs`` (right-hand side) of a lookup is the value we are comparing the
+ left hand side to. It may be a plain value, or something which compiles
+ into SQL, for example an ``F()`` object or a ``Queryset``.
+
+.. attribute:: lookup_name
+
+ This class level attribute is used when registering lookups. It determines
+ the name used in queries to trigger this lookup. For example, ``contains``
+ or ``exact``. This should not contain the string ``__``.
+
+.. method:: process_lhs(qn, connection)
+
+ This returns a tuple of ``(lhs_string, lhs_params)``. In some cases you may
+ wish to compile ``lhs`` directly in your ``as_sql`` methods using
+ ``qn.compile(self.lhs)``.
+
+.. method:: process_rhs(qn, connection)
+
+ Behaves the same as ``process_lhs`` but acts on the right-hand side.
+
+Transform reference
+~~~~~~~~~~~~~~~~~~~
+
+.. class:: Transform
+
+ In addition to implementing the query expression API Transforms have the
+ following methods and attributes.
+
+.. attribute:: lhs
+
+ The ``lhs`` (left-hand-side) of a transform contains the value to be
+ transformed. The ``lhs`` implements the query expression API.
+
+.. attribute:: lookup_name
+
+ This class level attribute is used when registering lookups. It determines
+ the name used in queries to trigger this lookup. For example, ``year``
+ or ``dayofweek``. This should not contain the string ``__``.
+
+.. _lookup-registration-api:
+
+Registering and fetching lookups
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The lookup registration API is explained below.
+
+.. classmethod:: register_lookup(lookup)
+
+ Registers the Lookup or Transform for the class. For example
+ ``DateField.register_lookup(YearExact)`` will register ``YearExact`` for
+ all ``DateFields`` in the project, but also for fields that are instances
+ of a subclass of ``DateField`` (for example ``DateTimeField``).
+
+.. method:: get_lookup(lookup_name)
+
+ Django uses ``get_lookup(lookup_name)`` to fetch lookups or transforms.
+ The implementation of ``get_lookup()`` fetches lookups or transforms
+ registered for the current class based on their lookup_name attribute.
+
+The lookup registration API is available for ``Transform`` and ``Field`` classes.
View
7 docs/ref/models/fields.txt
@@ -343,6 +343,13 @@ underscores to spaces. See :ref:`Verbose field names <verbose-field-names>`.
A list of validators to run for this field. See the :doc:`validators
documentation </ref/validators>` for more information.
+Registering and fetching lookups
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+``Field`` implements the :ref:`lookup registration API <lookup-registration-api>`.
+The API can be used to customize which lookups are available for a field class, and
+how lookups are fetched from a field.
+
.. _model-field-types:
Field types
View
1  docs/ref/models/index.txt
@@ -13,3 +13,4 @@ Model API reference. For introductory material, see :doc:`/topics/db/models`.
instances
querysets
queries
+ custom-lookups
View
3  docs/ref/models/querysets.txt
@@ -1995,6 +1995,9 @@ specified as keyword arguments to the ``QuerySet`` methods :meth:`filter()`,
For an introduction, see :ref:`models and database queries documentation
<field-lookups-intro>`.
+Django's inbuilt lookups are listed below. It is also possible to write
+:doc:`custom lookups </ref/models/custom-lookups>` for model fields.
+
.. fieldlookup:: exact
exact
View
21 docs/releases/1.7.txt
@@ -180,6 +180,27 @@ for the following, instead of backend specific behavior.
finally:
c.close()
+Custom lookups
+~~~~~~~~~~~~~~
+
+It is now possible to write custom lookups and transforms for the ORM.
+Custom lookups work just like Django's inbuilt lookups (e.g. ``lte``,
+``icontains``) while transforms are a new concept.
+
+The :class:`django.db.models.Lookup` class provides a way to add lookup
+operators for model fields. As an example it is possible to add ``day_lte``
+opertor for ``DateFields``.
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opertor -> operator

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+
+The :class:`django.db.models.Transform` class allows transformations of
+database values prior to the final lookup. For example it is possible to
+write a ``year`` transform that extracts year from the field's value.
+Transforms allow for chaining. After the ``year`` transform has been added
+to ``DateField`` it is possible to filter on the transformed value, for
+example ``qs.filter(author__birthdate__year__lte=1981)``.
+
+For more information about both custom lookups and transforms refer to
+:doc:`custom lookups </ref/models/custom-lookups>` documentation.
+
Minor features
~~~~~~~~~~~~~~
View
2  tests/aggregation/tests.py
@@ -443,7 +443,7 @@ def test_annotation(self):
vals = Author.objects.filter(pk=1).aggregate(Count("friends__id"))
self.assertEqual(vals, {"friends__id__count": 2})
- books = Book.objects.annotate(num_authors=Count("authors__name")).filter(num_authors__ge=2).order_by("pk")
+ books = Book.objects.annotate(num_authors=Count("authors__name")).filter(num_authors__exact=2).order_by("pk")
self.assertQuerysetEqual(
books, [
"The Definitive Guide to Django: Web Development Done Right",
View
0  tests/custom_lookups/__init__.py
No changes.
View
13 tests/custom_lookups/models.py
@@ -0,0 +1,13 @@
+from django.db import models
+from django.utils.encoding import python_2_unicode_compatible
+
+
+@python_2_unicode_compatible
+class Author(models.Model):
+ name = models.CharField(max_length=20)
+ age = models.IntegerField(null=True)
+ birthdate = models.DateField(null=True)
+ average_rating = models.FloatField(null=True)
+
+ def __str__(self):
+ return self.name
View
279 tests/custom_lookups/tests.py
@@ -0,0 +1,279 @@
+from datetime import date
+import unittest
+
+from django.test import TestCase
+from .models import Author
+from django.db import models
+from django.db import connection
+
+
+class Div3Lookup(models.Lookup):
+ lookup_name = 'div3'
+
+ def as_sql(self, qn, connection):
+ lhs, params = self.process_lhs(qn, connection)
+ rhs, rhs_params = self.process_rhs(qn, connection)
+ params.extend(rhs_params)
+ return '%s %%%% 3 = %s' % (lhs, rhs), params
+
+
+class Div3Transform(models.Transform):
+ lookup_name = 'div3'
+
+ def as_sql(self, qn, connection):
+ lhs, lhs_params = qn.compile(self.lhs)
+ return '%s %%%% 3' % (lhs,), lhs_params
+
+
+class YearTransform(models.Transform):
+ lookup_name = 'year'
+
+ def as_sql(self, qn, connection):
+ lhs_sql, params = qn.compile(self.lhs)
+ return connection.ops.date_extract_sql('year', lhs_sql), params
+
+ @property
+ def output_type(self):
+ return models.IntegerField()
+
+
+class YearExact(models.lookups.Lookup):
+ lookup_name = 'exact'
+
+ def as_sql(self, qn, connection):
+ # We will need to skip the extract part, and instead go
+ # directly with the originating field, that is self.lhs.lhs
+ lhs_sql, lhs_params = self.process_lhs(qn, connection, self.lhs.lhs)
+ rhs_sql, rhs_params = self.process_rhs(qn, connection)
+ # Note that we must be careful so that we have params in the
+ # same order as we have the parts in the SQL.
+ params = lhs_params + rhs_params + lhs_params + rhs_params
+ # We use PostgreSQL specific SQL here. Note that we must do the
+ # conversions in SQL instead of in Python to support F() references.
+ return ("%(lhs)s >= (%(rhs)s || '-01-01')::date "
+ "AND %(lhs)s <= (%(rhs)s || '-12-31')::date" %
+ {'lhs': lhs_sql, 'rhs': rhs_sql}, params)
+YearTransform.register_lookup(YearExact)
+
+
+class YearLte(models.lookups.LessThanOrEqual):
+ """
+ The purpose of this lookup is to efficiently compare the year of the field.
+ """
+
+ def as_sql(self, qn, connection):
+ # Skip the YearTransform above us (no possibility for efficient
+ # lookup otherwise).
+ real_lhs = self.lhs.lhs
+ lhs_sql, params = self.process_lhs(qn, connection, real_lhs)
+ rhs_sql, rhs_params = self.process_rhs(qn, connection)
+ params.extend(rhs_params)
+ # Build SQL where the integer year is concatenated with last month
+ # and day, then convert that to date. (We try to have SQL like:
+ # WHERE somecol <= '2013-12-31')
+ # but also make it work if the rhs_sql is field reference.
+ return "%s <= (%s || '-12-31')::date" % (lhs_sql, rhs_sql), params
+YearTransform.register_lookup(YearLte)
+
+
+# We will register this class temporarily in the test method.
+
+
+class InMonth(models.lookups.Lookup):
+ """
+ InMonth matches if the column's month is the same as value's month.
+ """
+ lookup_name = 'inmonth'
+
+ def as_sql(self, qn, connection):
+ lhs, lhs_params = self.process_lhs(qn, connection)
+ rhs, rhs_params = self.process_rhs(qn, connection)
+ # We need to be careful so that we get the params in right
+ # places.
+ params = lhs_params + rhs_params + lhs_params + rhs_params
+ return ("%s >= date_trunc('month', %s) and "
+ "%s < date_trunc('month', %s) + interval '1 months'" %
+ (lhs, rhs, lhs, rhs), params)
+
+
+class LookupTests(TestCase):
+ def test_basic_lookup(self):
+ a1 = Author.objects.create(name='a1', age=1)
+ a2 = Author.objects.create(name='a2', age=2)
+ a3 = Author.objects.create(name='a3', age=3)
+ a4 = Author.objects.create(name='a4', age=4)
+ models.IntegerField.register_lookup(Div3Lookup)
+ try:
+ self.assertQuerysetEqual(
+ Author.objects.filter(age__div3=0),
+ [a3], lambda x: x