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import re
import warnings
from itertools import chain
from django.core.exceptions import FieldError
from django.db.models.constants import LOOKUP_SEP
from django.db.models.expressions import OrderBy, Random, RawSQL, Ref
from django.db.models.query_utils import QueryWrapper, select_related_descend
from django.db.models.sql.constants import (
CURSOR, GET_ITERATOR_CHUNK_SIZE, MULTI, NO_RESULTS, ORDER_DIR, SINGLE,
)
from django.db.models.sql.datastructures import EmptyResultSet
from django.db.models.sql.query import Query, get_order_dir
from django.db.transaction import TransactionManagementError
from django.db.utils import DatabaseError
from django.utils.deprecation import RemovedInDjango20Warning
from django.utils.six.moves import zip
class SQLCompiler(object):
def __init__(self, query, connection, using):
self.query = query
self.connection = connection
self.using = using
self.quote_cache = {'*': '*'}
# The select, klass_info, and annotations are needed by QuerySet.iterator()
# these are set as a side-effect of executing the query. Note that we calculate
# separately a list of extra select columns needed for grammatical correctness
# of the query, but these columns are not included in self.select.
self.select = None
self.annotation_col_map = None
self.klass_info = None
self.ordering_parts = re.compile(r'(.*)\s(ASC|DESC)(.*)')
self.subquery = False
def setup_query(self):
if all(self.query.alias_refcount[a] == 0 for a in self.query.tables):
self.query.get_initial_alias()
self.select, self.klass_info, self.annotation_col_map = self.get_select()
self.col_count = len(self.select)
def pre_sql_setup(self):
"""
Does any necessary class setup immediately prior to producing SQL. This
is for things that can't necessarily be done in __init__ because we
might not have all the pieces in place at that time.
"""
self.setup_query()
order_by = self.get_order_by()
self.where, self.having = self.query.where.split_having()
extra_select = self.get_extra_select(order_by, self.select)
group_by = self.get_group_by(self.select + extra_select, order_by)
return extra_select, order_by, group_by
def get_group_by(self, select, order_by):
"""
Returns a list of 2-tuples of form (sql, params).
The logic of what exactly the GROUP BY clause contains is hard
to describe in other words than "if it passes the test suite,
then it is correct".
"""
# Some examples:
# SomeModel.objects.annotate(Count('somecol'))
# GROUP BY: all fields of the model
#
# SomeModel.objects.values('name').annotate(Count('somecol'))
# GROUP BY: name
#
# SomeModel.objects.annotate(Count('somecol')).values('name')
# GROUP BY: all cols of the model
#
# SomeModel.objects.values('name', 'pk').annotate(Count('somecol')).values('pk')
# GROUP BY: name, pk
#
# SomeModel.objects.values('name').annotate(Count('somecol')).values('pk')
# GROUP BY: name, pk
#
# In fact, the self.query.group_by is the minimal set to GROUP BY. It
# can't be ever restricted to a smaller set, but additional columns in
# HAVING, ORDER BY, and SELECT clauses are added to it. Unfortunately
# the end result is that it is impossible to force the query to have
# a chosen GROUP BY clause - you can almost do this by using the form:
# .values(*wanted_cols).annotate(AnAggregate())
# but any later annotations, extra selects, values calls that
# refer some column outside of the wanted_cols, order_by, or even
# filter calls can alter the GROUP BY clause.
# The query.group_by is either None (no GROUP BY at all), True
# (group by select fields), or a list of expressions to be added
# to the group by.
if self.query.group_by is None:
return []
expressions = []
if self.query.group_by is not True:
# If the group by is set to a list (by .values() call most likely),
# then we need to add everything in it to the GROUP BY clause.
# Backwards compatibility hack for setting query.group_by. Remove
# when we have public API way of forcing the GROUP BY clause.
# Converts string references to expressions.
for expr in self.query.group_by:
if not hasattr(expr, 'as_sql'):
expressions.append(self.query.resolve_ref(expr))
else:
expressions.append(expr)
# Note that even if the group_by is set, it is only the minimal
# set to group by. So, we need to add cols in select, order_by, and
# having into the select in any case.
for expr, _, _ in select:
cols = expr.get_group_by_cols()
for col in cols:
expressions.append(col)
for expr, (sql, params, is_ref) in order_by:
if expr.contains_aggregate:
continue
# We can skip References to select clause, as all expressions in
# the select clause are already part of the group by.
if is_ref:
continue
expressions.extend(expr.get_source_expressions())
having_group_by = self.having.get_group_by_cols() if self.having else ()
for expr in having_group_by:
expressions.append(expr)
result = []
seen = set()
expressions = self.collapse_group_by(expressions, having_group_by)
for expr in expressions:
sql, params = self.compile(expr)
if (sql, tuple(params)) not in seen:
result.append((sql, params))
seen.add((sql, tuple(params)))
return result
def collapse_group_by(self, expressions, having):
# If the DB can group by primary key, then group by the primary key of
# query's main model. Note that for PostgreSQL the GROUP BY clause must
# include the primary key of every table, but for MySQL it is enough to
# have the main table's primary key. Currently only the MySQL form is
# implemented.
# MySQLism: however, columns in HAVING clause must be added to the
# GROUP BY.
if self.connection.features.allows_group_by_pk:
# The logic here is: if the main model's primary key is in the
# query, then set new_expressions to that field. If that happens,
# then also add having expressions to group by.
pk = None
for expr in expressions:
if (expr.output_field.primary_key and
getattr(expr.output_field, 'model') == self.query.model):
pk = expr
if pk:
expressions = [pk] + [expr for expr in expressions if expr in having]
return expressions
def get_select(self):
"""
Returns three values:
- a list of 3-tuples of (expression, (sql, params), alias)
- a klass_info structure,
- a dictionary of annotations
The (sql, params) is what the expression will produce, and alias is the
"AS alias" for the column (possibly None).
The klass_info structure contains the following information:
- Which model to instantiate
- Which columns for that model are present in the query (by
position of the select clause).
- related_klass_infos: [f, klass_info] to descent into
The annotations is a dictionary of {'attname': column position} values.
"""
select = []
klass_info = None
annotations = {}
select_idx = 0
for alias, (sql, params) in self.query.extra_select.items():
annotations[alias] = select_idx
select.append((RawSQL(sql, params), alias))
select_idx += 1
assert not (self.query.select and self.query.default_cols)
if self.query.default_cols:
select_list = []
for c in self.get_default_columns():
select_list.append(select_idx)
select.append((c, None))
select_idx += 1
klass_info = {
'model': self.query.model,
'select_fields': select_list,
}
# self.query.select is a special case. These columns never go to
# any model.
for col in self.query.select:
select.append((col, None))
select_idx += 1
for alias, annotation in self.query.annotation_select.items():
annotations[alias] = select_idx
select.append((annotation, alias))
select_idx += 1
if self.query.select_related:
related_klass_infos = self.get_related_selections(select)
klass_info['related_klass_infos'] = related_klass_infos
def get_select_from_parent(klass_info):
for ki in klass_info['related_klass_infos']:
if ki['from_parent']:
ki['select_fields'] = (klass_info['select_fields'] +
ki['select_fields'])
get_select_from_parent(ki)
get_select_from_parent(klass_info)
ret = []
for col, alias in select:
ret.append((col, self.compile(col, select_format=True), alias))
return ret, klass_info, annotations
def get_order_by(self):
"""
Returns a list of 2-tuples of form (expr, (sql, params)) for the
ORDER BY clause.
The order_by clause can alter the select clause (for example it
can add aliases to clauses that do not yet have one, or it can
add totally new select clauses).
"""
if self.query.extra_order_by:
ordering = self.query.extra_order_by
elif not self.query.default_ordering:
ordering = self.query.order_by
else:
ordering = (self.query.order_by or self.query.get_meta().ordering or [])
if self.query.standard_ordering:
asc, desc = ORDER_DIR['ASC']
else:
asc, desc = ORDER_DIR['DESC']
order_by = []
for pos, field in enumerate(ordering):
if hasattr(field, 'resolve_expression'):
if not isinstance(field, OrderBy):
field = field.asc()
if not self.query.standard_ordering:
field.reverse_ordering()
order_by.append((field, False))
continue
if field == '?': # random
order_by.append((OrderBy(Random()), False))
continue
col, order = get_order_dir(field, asc)
descending = True if order == 'DESC' else False
if col in self.query.annotation_select:
order_by.append((
OrderBy(Ref(col, self.query.annotation_select[col]), descending=descending),
True))
continue
if '.' in field:
# This came in through an extra(order_by=...) addition. Pass it
# on verbatim.
table, col = col.split('.', 1)
order_by.append((
OrderBy(
RawSQL('%s.%s' % (self.quote_name_unless_alias(table), col), []),
descending=descending
), False))
continue
if not self.query._extra or col not in self.query._extra:
# 'col' is of the form 'field' or 'field1__field2' or
# '-field1__field2__field', etc.
order_by.extend(self.find_ordering_name(
field, self.query.get_meta(), default_order=asc))
else:
if col not in self.query.extra_select:
order_by.append((
OrderBy(RawSQL(*self.query.extra[col]), descending=descending),
False))
else:
order_by.append((
OrderBy(Ref(col, RawSQL(*self.query.extra[col])), descending=descending),
True))
result = []
seen = set()
for expr, is_ref in order_by:
resolved = expr.resolve_expression(
self.query, allow_joins=True, reuse=None)
sql, params = self.compile(resolved)
# Don't add the same column twice, but the order direction is
# not taken into account so we strip it. When this entire method
# is refactored into expressions, then we can check each part as we
# generate it.
without_ordering = self.ordering_parts.search(sql).group(1)
if (without_ordering, tuple(params)) in seen:
continue
seen.add((without_ordering, tuple(params)))
result.append((resolved, (sql, params, is_ref)))
return result
def get_extra_select(self, order_by, select):
extra_select = []
select_sql = [t[1] for t in select]
if self.query.distinct and not self.query.distinct_fields:
for expr, (sql, params, is_ref) in order_by:
without_ordering = self.ordering_parts.search(sql).group(1)
if not is_ref and (without_ordering, params) not in select_sql:
extra_select.append((expr, (without_ordering, params), None))
return extra_select
def __call__(self, name):
"""
Backwards-compatibility shim so that calling a SQLCompiler is equivalent to
calling its quote_name_unless_alias method.
"""
warnings.warn(
"Calling a SQLCompiler directly is deprecated. "
"Call compiler.quote_name_unless_alias instead.",
RemovedInDjango20Warning, stacklevel=2)
return self.quote_name_unless_alias(name)
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).
"""
if name in self.quote_cache:
return self.quote_cache[name]
if ((name in self.query.alias_map and name not in self.query.table_map) or
name in self.query.extra_select or name in self.query.external_aliases):
self.quote_cache[name] = name
return name
r = self.connection.ops.quote_name(name)
self.quote_cache[name] = r
return r
def compile(self, node, select_format=False):
vendor_impl = getattr(node, 'as_' + self.connection.vendor, None)
if vendor_impl:
sql, params = vendor_impl(self, self.connection)
else:
sql, params = node.as_sql(self, self.connection)
if select_format and not self.subquery:
return node.output_field.select_format(self, sql, params)
return sql, params
def as_sql(self, with_limits=True, with_col_aliases=False, subquery=False):
"""
Creates the SQL for this query. Returns the SQL string and list of
parameters.
If 'with_limits' is False, any limit/offset information is not included
in the query.
"""
if with_limits and self.query.low_mark == self.query.high_mark:
return '', ()
self.subquery = subquery
refcounts_before = self.query.alias_refcount.copy()
try:
extra_select, order_by, group_by = self.pre_sql_setup()
if with_limits and self.query.low_mark == self.query.high_mark:
return '', ()
distinct_fields = self.get_distinct()
# This must come after 'select', 'ordering', and 'distinct' -- see
# docstring of get_from_clause() for details.
from_, f_params = self.get_from_clause()
where, w_params = self.compile(self.where) if self.where is not None else ("", [])
having, h_params = self.compile(self.having) if self.having is not None else ("", [])
params = []
result = ['SELECT']
if self.query.distinct:
result.append(self.connection.ops.distinct_sql(distinct_fields))
out_cols = []
col_idx = 1
for _, (s_sql, s_params), alias in self.select + extra_select:
if alias:
s_sql = '%s AS %s' % (s_sql, self.connection.ops.quote_name(alias))
elif with_col_aliases:
s_sql = '%s AS %s' % (s_sql, 'Col%d' % col_idx)
col_idx += 1
params.extend(s_params)
out_cols.append(s_sql)
result.append(', '.join(out_cols))
result.append('FROM')
result.extend(from_)
params.extend(f_params)
if where:
result.append('WHERE %s' % where)
params.extend(w_params)
grouping = []
for g_sql, g_params in group_by:
grouping.append(g_sql)
params.extend(g_params)
if grouping:
if distinct_fields:
raise NotImplementedError(
"annotate() + distinct(fields) is not implemented.")
if not order_by:
order_by = self.connection.ops.force_no_ordering()
result.append('GROUP BY %s' % ', '.join(grouping))
if having:
result.append('HAVING %s' % having)
params.extend(h_params)
if order_by:
ordering = []
for _, (o_sql, o_params, _) in order_by:
ordering.append(o_sql)
params.extend(o_params)
result.append('ORDER BY %s' % ', '.join(ordering))
if with_limits:
if self.query.high_mark is not None:
result.append('LIMIT %d' % (self.query.high_mark - self.query.low_mark))
if self.query.low_mark:
if self.query.high_mark is None:
val = self.connection.ops.no_limit_value()
if val:
result.append('LIMIT %d' % val)
result.append('OFFSET %d' % self.query.low_mark)
if self.query.select_for_update and self.connection.features.has_select_for_update:
if self.connection.get_autocommit():
raise TransactionManagementError(
"select_for_update cannot be used outside of a transaction."
)
# If we've been asked for a NOWAIT query but the backend does
# not support it, raise a DatabaseError otherwise we could get
# an unexpected deadlock.
nowait = self.query.select_for_update_nowait
if nowait and not self.connection.features.has_select_for_update_nowait:
raise DatabaseError('NOWAIT is not supported on this database backend.')
result.append(self.connection.ops.for_update_sql(nowait=nowait))
return ' '.join(result), tuple(params)
finally:
# Finally do cleanup - get rid of the joins we created above.
self.query.reset_refcounts(refcounts_before)
def as_nested_sql(self):
"""
Perform the same functionality as the as_sql() method, returning an
SQL string and parameters. However, the alias prefixes are bumped
beforehand (in a copy -- the current query isn't changed), and any
ordering is removed if the query is unsliced.
Used when nesting this query inside another.
"""
obj = self.query.clone()
if obj.low_mark == 0 and obj.high_mark is None and not self.query.distinct_fields:
# If there is no slicing in use, then we can safely drop all ordering
obj.clear_ordering(True)
return obj.get_compiler(connection=self.connection).as_sql(subquery=True)
def get_default_columns(self, start_alias=None, opts=None, from_parent=None):
"""
Computes the default columns for selecting every field in the base
model. Will sometimes be called to pull in related models (e.g. via
select_related), in which case "opts" and "start_alias" will be given
to provide a starting point for the traversal.
Returns a list of strings, quoted appropriately for use in SQL
directly, as well as a set of aliases used in the select statement (if
'as_pairs' is True, returns a list of (alias, col_name) pairs instead
of strings as the first component and None as the second component).
"""
result = []
if opts is None:
opts = self.query.get_meta()
only_load = self.deferred_to_columns()
if not start_alias:
start_alias = self.query.get_initial_alias()
# The 'seen_models' is used to optimize checking the needed parent
# alias for a given field. This also includes None -> start_alias to
# be used by local fields.
seen_models = {None: start_alias}
for field in opts.concrete_fields:
model = field.model._meta.concrete_model
# A proxy model will have a different model and concrete_model. We
# will assign None if the field belongs to this model.
if model == opts.model:
model = None
if from_parent and model is not None and issubclass(
from_parent._meta.concrete_model, model._meta.concrete_model):
# Avoid loading data for already loaded parents.
# We end up here in the case select_related() resolution
# proceeds from parent model to child model. In that case the
# parent model data is already present in the SELECT clause,
# and we want to avoid reloading the same data again.
continue
if field.model in only_load and field.attname not in only_load[field.model]:
continue
alias = self.query.join_parent_model(opts, model, start_alias,
seen_models)
column = field.get_col(alias)
result.append(column)
return result
def get_distinct(self):
"""
Returns a quoted list of fields to use in DISTINCT ON part of the query.
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
qn2 = self.connection.ops.quote_name
result = []
opts = self.query.get_meta()
for name in self.query.distinct_fields:
parts = name.split(LOOKUP_SEP)
_, targets, alias, joins, path, _ = self._setup_joins(parts, opts, None)
targets, alias, _ = self.query.trim_joins(targets, joins, path)
for target in targets:
result.append("%s.%s" % (qn(alias), qn2(target.column)))
return result
def find_ordering_name(self, name, opts, alias=None, default_order='ASC',
already_seen=None):
"""
Returns the table alias (the name might be ambiguous, the alias will
not be) and column name for ordering by the given 'name' parameter.
The 'name' is of the form 'field1__field2__...__fieldN'.
"""
name, order = get_order_dir(name, default_order)
descending = True if order == 'DESC' else False
pieces = name.split(LOOKUP_SEP)
field, targets, alias, joins, path, opts = self._setup_joins(pieces, opts, alias)
# If we get to this point and the field is a relation to another model,
# append the default ordering for that model unless the attribute name
# of the field is specified.
if field.is_relation and path and opts.ordering and name != field.attname:
# Firstly, avoid infinite loops.
if not already_seen:
already_seen = set()
join_tuple = tuple(self.query.alias_map[j].table_name for j in joins)
if join_tuple in already_seen:
raise FieldError('Infinite loop caused by ordering.')
already_seen.add(join_tuple)
results = []
for item in opts.ordering:
results.extend(self.find_ordering_name(item, opts, alias,
order, already_seen))
return results
targets, alias, _ = self.query.trim_joins(targets, joins, path)
return [(OrderBy(t.get_col(alias), descending=descending), False) for t in targets]
def _setup_joins(self, pieces, opts, alias):
"""
A helper method for get_order_by and get_distinct.
Note that get_ordering and get_distinct must produce same target
columns on same input, as the prefixes of get_ordering and get_distinct
must match. Executing SQL where this is not true is an error.
"""
if not alias:
alias = self.query.get_initial_alias()
field, targets, opts, joins, path = self.query.setup_joins(
pieces, opts, alias)
alias = joins[-1]
return field, targets, alias, joins, path, opts
def get_from_clause(self):
"""
Returns a list of strings that are joined together to go after the
"FROM" part of the query, as well as a list any extra parameters that
need to be included. Sub-classes, can override this to create a
from-clause via a "select".
This should only be called after any SQL construction methods that
might change the tables we need. This means the select columns,
ordering and distinct must be done first.
"""
result = []
params = []
for alias in self.query.tables:
if not self.query.alias_refcount[alias]:
continue
try:
from_clause = self.query.alias_map[alias]
except KeyError:
# Extra tables can end up in self.tables, but not in the
# alias_map if they aren't in a join. That's OK. We skip them.
continue
clause_sql, clause_params = self.compile(from_clause)
result.append(clause_sql)
params.extend(clause_params)
for t in self.query.extra_tables:
alias, _ = self.query.table_alias(t)
# Only add the alias if it's not already present (the table_alias()
# call increments the refcount, so an alias refcount of one means
# this is the only reference).
if alias not in self.query.alias_map or self.query.alias_refcount[alias] == 1:
result.append(', %s' % self.quote_name_unless_alias(alias))
return result, params
def get_related_selections(self, select, opts=None, root_alias=None, cur_depth=1,
requested=None, restricted=None):
"""
Fill in the information needed for a select_related query. The current
depth is measured as the number of connections away from the root model
(for example, cur_depth=1 means we are looking at models with direct
connections to the root model).
"""
def _get_field_choices():
direct_choices = (f.name for f in opts.fields if f.is_relation)
reverse_choices = (
f.field.related_query_name()
for f in opts.related_objects if f.field.unique
)
return chain(direct_choices, reverse_choices)
related_klass_infos = []
if not restricted and self.query.max_depth and cur_depth > self.query.max_depth:
# We've recursed far enough; bail out.
return related_klass_infos
if not opts:
opts = self.query.get_meta()
root_alias = self.query.get_initial_alias()
only_load = self.query.get_loaded_field_names()
# Setup for the case when only particular related fields should be
# included in the related selection.
fields_found = set()
if requested is None:
if isinstance(self.query.select_related, dict):
requested = self.query.select_related
restricted = True
else:
restricted = False
def get_related_klass_infos(klass_info, related_klass_infos):
klass_info['related_klass_infos'] = related_klass_infos
for f in opts.fields:
field_model = f.model._meta.concrete_model
fields_found.add(f.name)
if restricted:
next = requested.get(f.name, {})
if not f.is_relation:
# If a non-related field is used like a relation,
# or if a single non-relational field is given.
if next or (cur_depth == 1 and f.name in requested):
raise FieldError(
"Non-relational field given in select_related: '%s'. "
"Choices are: %s" % (
f.name,
", ".join(_get_field_choices()) or '(none)',
)
)
else:
next = False
if not select_related_descend(f, restricted, requested,
only_load.get(field_model)):
continue
klass_info = {
'model': f.remote_field.model,
'field': f,
'reverse': False,
'from_parent': False,
}
related_klass_infos.append(klass_info)
select_fields = []
_, _, _, joins, _ = self.query.setup_joins(
[f.name], opts, root_alias)
alias = joins[-1]
columns = self.get_default_columns(start_alias=alias, opts=f.remote_field.model._meta)
for col in columns:
select_fields.append(len(select))
select.append((col, None))
klass_info['select_fields'] = select_fields
next_klass_infos = self.get_related_selections(
select, f.remote_field.model._meta, alias, cur_depth + 1, next, restricted)
get_related_klass_infos(klass_info, next_klass_infos)
if restricted:
related_fields = [
(o.field, o.related_model)
for o in opts.related_objects
if o.field.unique and not o.many_to_many
]
for f, model in related_fields:
if not select_related_descend(f, restricted, requested,
only_load.get(model), reverse=True):
continue
related_field_name = f.related_query_name()
fields_found.add(related_field_name)
_, _, _, joins, _ = self.query.setup_joins([related_field_name], opts, root_alias)
alias = joins[-1]
from_parent = issubclass(model, opts.model)
klass_info = {
'model': model,
'field': f,
'reverse': True,
'from_parent': from_parent,
}
related_klass_infos.append(klass_info)
select_fields = []
columns = self.get_default_columns(
start_alias=alias, opts=model._meta, from_parent=opts.model)
for col in columns:
select_fields.append(len(select))
select.append((col, None))
klass_info['select_fields'] = select_fields
next = requested.get(f.related_query_name(), {})
next_klass_infos = self.get_related_selections(
select, model._meta, alias, cur_depth + 1,
next, restricted)
get_related_klass_infos(klass_info, next_klass_infos)
fields_not_found = set(requested.keys()).difference(fields_found)
if fields_not_found:
invalid_fields = ("'%s'" % s for s in fields_not_found)
raise FieldError(
'Invalid field name(s) given in select_related: %s. '
'Choices are: %s' % (
', '.join(invalid_fields),
', '.join(_get_field_choices()) or '(none)',
)
)
return related_klass_infos
def deferred_to_columns(self):
"""
Converts the self.deferred_loading data structure to mapping of table
names to sets of column names which are to be loaded. Returns the
dictionary.
"""
columns = {}
self.query.deferred_to_data(columns, self.query.get_loaded_field_names_cb)
return columns
def get_converters(self, expressions):
converters = {}
for i, expression in enumerate(expressions):
if expression:
backend_converters = self.connection.ops.get_db_converters(expression)
field_converters = expression.get_db_converters(self.connection)
if backend_converters or field_converters:
converters[i] = (backend_converters + field_converters, expression)
return converters
def apply_converters(self, row, converters):
row = list(row)
for pos, (convs, expression) in converters.items():
value = row[pos]
for converter in convs:
value = converter(value, expression, self.connection, self.query.context)
row[pos] = value
return tuple(row)
def results_iter(self, results=None):
"""
Returns an iterator over the results from executing this query.
"""
converters = None
if results is None:
results = self.execute_sql(MULTI)
fields = [s[0] for s in self.select[0:self.col_count]]
converters = self.get_converters(fields)
for rows in results:
for row in rows:
if converters:
row = self.apply_converters(row, converters)
yield row
def has_results(self):
"""
Backends (e.g. NoSQL) can override this in order to use optimized
versions of "query has any results."
"""
# This is always executed on a query clone, so we can modify self.query
self.query.add_extra({'a': 1}, None, None, None, None, None)
self.query.set_extra_mask(['a'])
return bool(self.execute_sql(SINGLE))
def execute_sql(self, result_type=MULTI):
"""
Run the query against the database and returns the result(s). The
return value is a single data item if result_type is SINGLE, or an
iterator over the results if the result_type is MULTI.
result_type is either MULTI (use fetchmany() to retrieve all rows),
SINGLE (only retrieve a single row), or None. In this last case, the
cursor is returned if any query is executed, since it's used by
subclasses such as InsertQuery). It's possible, however, that no query
is needed, as the filters describe an empty set. In that case, None is
returned, to avoid any unnecessary database interaction.
"""
if not result_type:
result_type = NO_RESULTS
try:
sql, params = self.as_sql()
if not sql:
raise EmptyResultSet
except EmptyResultSet:
if result_type == MULTI:
return iter([])
else:
return
cursor = self.connection.cursor()
try:
cursor.execute(sql, params)
except Exception:
cursor.close()
raise
if result_type == CURSOR:
# Caller didn't specify a result_type, so just give them back the
# cursor to process (and close).
return cursor
if result_type == SINGLE:
try:
val = cursor.fetchone()
if val:
return val[0:self.col_count]
return val
finally:
# done with the cursor
cursor.close()
if result_type == NO_RESULTS:
cursor.close()
return
result = cursor_iter(
cursor, self.connection.features.empty_fetchmany_value,
self.col_count
)
if not self.connection.features.can_use_chunked_reads:
try:
# If we are using non-chunked reads, we return the same data
# structure as normally, but ensure it is all read into memory
# before going any further.
return list(result)
finally:
# done with the cursor
cursor.close()
return result
def as_subquery_condition(self, alias, columns, compiler):
qn = compiler.quote_name_unless_alias
qn2 = self.connection.ops.quote_name
if len(columns) == 1:
sql, params = self.as_sql()
return '%s.%s IN (%s)' % (qn(alias), qn2(columns[0]), sql), params
for index, select_col in enumerate(self.query.select):
lhs_sql, lhs_params = self.compile(select_col)
rhs = '%s.%s' % (qn(alias), qn2(columns[index]))
self.query.where.add(
QueryWrapper('%s = %s' % (lhs_sql, rhs), lhs_params), 'AND')
sql, params = self.as_sql()
return 'EXISTS (%s)' % sql, params
class SQLInsertCompiler(SQLCompiler):
def __init__(self, *args, **kwargs):
self.return_id = False
super(SQLInsertCompiler, self).__init__(*args, **kwargs)
def placeholder(self, field, val):
if field is None:
# A field value of None means the value is raw.
return val
elif hasattr(field, 'get_placeholder'):
# Some fields (e.g. geo fields) need special munging before
# they can be inserted.
return field.get_placeholder(val, self, self.connection)
else:
# Return the common case for the placeholder
return '%s'
def as_sql(self):
# We don't need quote_name_unless_alias() here, since these are all
# going to be column names (so we can avoid the extra overhead).
qn = self.connection.ops.quote_name
opts = self.query.get_meta()
result = ['INSERT INTO %s' % qn(opts.db_table)]
has_fields = bool(self.query.fields)
fields = self.query.fields if has_fields else [opts.pk]
result.append('(%s)' % ', '.join(qn(f.column) for f in fields))
if has_fields:
params = values = [
[
f.get_db_prep_save(
getattr(obj, f.attname) if self.query.raw else f.pre_save(obj, True),
connection=self.connection
) for f in fields
]
for obj in self.query.objs
]
else:
values = [[self.connection.ops.pk_default_value()] for obj in self.query.objs]
params = [[]]
fields = [None]
can_bulk = (not any(hasattr(field, "get_placeholder") for field in fields) and
not self.return_id and self.connection.features.has_bulk_insert)
if can_bulk:
placeholders = [["%s"] * len(fields)]
else:
placeholders = [
[self.placeholder(field, v) for field, v in zip(fields, val)]
for val in values
]
# Oracle Spatial needs to remove some values due to #10888
params = self.connection.ops.modify_insert_params(placeholders, params)
if self.return_id and self.connection.features.can_return_id_from_insert:
params = params[0]
col = "%s.%s" % (qn(opts.db_table), qn(opts.pk.column))
result.append("VALUES (%s)" % ", ".join(placeholders[0]))
r_fmt, r_params = self.connection.ops.return_insert_id()
# Skip empty r_fmt to allow subclasses to customize behavior for
# 3rd party backends. Refs #19096.
if r_fmt:
result.append(r_fmt % col)
params += r_params
return [(" ".join(result), tuple(params))]
if can_bulk:
result.append(self.connection.ops.bulk_insert_sql(fields, len(values)))
return [(" ".join(result), tuple(v for val in values for v in val))]
else:
return [
(" ".join(result + ["VALUES (%s)" % ", ".join(p)]), vals)
for p, vals in zip(placeholders, params)
]
def execute_sql(self, return_id=False):
assert not (return_id and len(self.query.objs) != 1)
self.return_id = return_id
with self.connection.cursor() as cursor:
for sql, params in self.as_sql():
cursor.execute(sql, params)
if not (return_id and cursor):
return
if self.connection.features.can_return_id_from_insert:
return self.connection.ops.fetch_returned_insert_id(cursor)
return self.connection.ops.last_insert_id(cursor,
self.query.get_meta().db_table, self.query.get_meta().pk.column)
class SQLDeleteCompiler(SQLCompiler):
def as_sql(self):
"""
Creates the SQL for this query. Returns the SQL string and list of
parameters.
"""
assert len(self.query.tables) == 1, \
"Can only delete from one table at a time."
qn = self.quote_name_unless_alias
result = ['DELETE FROM %s' % qn(self.query.tables[0])]
where, params = self.compile(self.query.where)
if where:
result.append('WHERE %s' % where)
return ' '.join(result), tuple(params)
class SQLUpdateCompiler(SQLCompiler):
def as_sql(self):
"""
Creates the SQL for this query. Returns the SQL string and list of
parameters.
"""
self.pre_sql_setup()
if not self.query.values:
return '', ()
table = self.query.tables[0]
qn = self.quote_name_unless_alias
result = ['UPDATE %s' % qn(table)]
result.append('SET')
values, update_params = [], []
for field, model, val in self.query.values:
if hasattr(val, 'resolve_expression'):
val = val.resolve_expression(self.query, allow_joins=False, for_save=True)
if val.contains_aggregate:
raise FieldError("Aggregate functions are not allowed in this query")
elif hasattr(val, 'prepare_database_save'):
if field.remote_field:
val = val.prepare_database_save(field)
else:
raise TypeError("Database is trying to update a relational field "
"of type %s with a value of type %s. Make sure "
"you are setting the correct relations" %
(field.__class__.__name__, val.__class__.__name__))
else:
val = field.get_db_prep_save(val, connection=self.connection)
# Getting the placeholder for the field.
if hasattr(field, 'get_placeholder'):
placeholder = field.get_placeholder(val, self, self.connection)
else:
placeholder = '%s'
name = field.column
if hasattr(val, 'as_sql'):
sql, params = self.compile(val)
values.append('%s = %s' % (qn(name), sql))
update_params.extend(params)
elif val is not None:
values.append('%s = %s' % (qn(name), placeholder))
update_params.append(val)
else:
values.append('%s = NULL' % qn(name))
if not values:
return '', ()
result.append(', '.join(values))
where, params = self.compile(self.query.where)
if where:
result.append('WHERE %s' % where)
return ' '.join(result), tuple(update_params + params)
def execute_sql(self, result_type):
"""
Execute the specified update. Returns the number of rows affected by
the primary update query. The "primary update query" is the first
non-empty query that is executed. Row counts for any subsequent,
related queries are not available.
"""
cursor = super(SQLUpdateCompiler, self).execute_sql(result_type)
try:
rows = cursor.rowcount if cursor else 0
is_empty = cursor is None
finally:
if cursor:
cursor.close()
for query in self.query.get_related_updates():
aux_rows = query.get_compiler(self.using).execute_sql(result_type)
if is_empty and aux_rows:
rows = aux_rows
is_empty = False
return rows
def pre_sql_setup(self):
"""
If the update depends on results from other tables, we need to do some
munging of the "where" conditions to match the format required for
(portable) SQL updates. That is done here.
Further, if we are going to be running multiple updates, we pull out
the id values to update at this point so that they don't change as a
result of the progressive updates.
"""
refcounts_before = self.query.alias_refcount.copy()
# Ensure base table is in the query
self.query.get_initial_alias()
count = self.query.count_active_tables()
if not self.query.related_updates and count == 1:
return
query = self.query.clone(klass=Query)
query.select_related = False
query.clear_ordering(True)
query._extra = {}
query.select = []
query.add_fields([query.get_meta().pk.name])
super(SQLUpdateCompiler, self).pre_sql_setup()
must_pre_select = count > 1 and not self.connection.features.update_can_self_select
# Now we adjust the current query: reset the where clause and get rid
# of all the tables we don't need (since they're in the sub-select).
self.query.where = self.query.where_class()
if self.query.related_updates or must_pre_select:
# Either we're using the idents in multiple update queries (so
# don't want them to change), or the db backend doesn't support
# selecting from the updating table (e.g. MySQL).
idents = []
for rows in query.get_compiler(self.using).execute_sql(MULTI):
idents.extend(r[0] for r in rows)
self.query.add_filter(('pk__in', idents))
self.query.related_ids = idents
else:
# The fast path. Filters and updates in one query.
self.query.add_filter(('pk__in', query))
self.query.reset_refcounts(refcounts_before)
class SQLAggregateCompiler(SQLCompiler):
def as_sql(self):
"""
Creates the SQL for this query. Returns the SQL string and list of
parameters.
"""
# Empty SQL for the inner query is a marker that the inner query
# isn't going to produce any results. This can happen when doing
# LIMIT 0 queries (generated by qs[:0]) for example.
if not self.query.subquery:
raise EmptyResultSet
sql, params = [], []
for annotation in self.query.annotation_select.values():
ann_sql, ann_params = self.compile(annotation, select_format=True)
sql.append(ann_sql)
params.extend(ann_params)
self.col_count = len(self.query.annotation_select)
sql = ', '.join(sql)
params = tuple(params)
sql = 'SELECT %s FROM (%s) subquery' % (sql, self.query.subquery)
params = params + self.query.sub_params
return sql, params
def cursor_iter(cursor, sentinel, col_count):
"""
Yields blocks of rows from a cursor and ensures the cursor is closed when
done.
"""
try:
for rows in iter((lambda: cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)),
sentinel):
yield [r[0:col_count] for r in rows]
finally:
cursor.close()
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