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base.py
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base.py
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"""
PostgreSQL database backend for Django.
Requires psycopg 1: http://initd.org/projects/psycopg1
"""
from django.utils.encoding import smart_str, smart_unicode
from django.db.backends import BaseDatabaseWrapper, BaseDatabaseOperations, util
try:
import psycopg as Database
except ImportError, e:
from django.core.exceptions import ImproperlyConfigured
raise ImproperlyConfigured, "Error loading psycopg module: %s" % e
DatabaseError = Database.DatabaseError
IntegrityError = Database.IntegrityError
class UnicodeCursorWrapper(object):
"""
A thin wrapper around psycopg cursors that allows them to accept Unicode
strings as params.
This is necessary because psycopg doesn't apply any DB quoting to
parameters that are Unicode strings. If a param is Unicode, this will
convert it to a bytestring using database client's encoding before passing
it to psycopg.
All results retrieved from the database are converted into Unicode strings
before being returned to the caller.
"""
def __init__(self, cursor, charset):
self.cursor = cursor
self.charset = charset
def format_params(self, params):
if isinstance(params, dict):
result = {}
charset = self.charset
for key, value in params.items():
result[smart_str(key, charset)] = smart_str(value, charset)
return result
else:
return tuple([smart_str(p, self.charset, True) for p in params])
def execute(self, sql, params=()):
return self.cursor.execute(smart_str(sql, self.charset), self.format_params(params))
def executemany(self, sql, param_list):
new_param_list = [self.format_params(params) for params in param_list]
return self.cursor.executemany(sql, new_param_list)
def __getattr__(self, attr):
if attr in self.__dict__:
return self.__dict__[attr]
else:
return getattr(self.cursor, attr)
postgres_version = None
class DatabaseOperations(BaseDatabaseOperations):
def date_extract_sql(self, lookup_type, field_name):
# http://www.postgresql.org/docs/8.0/static/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT
return "EXTRACT('%s' FROM %s)" % (lookup_type, field_name)
def date_trunc_sql(self, lookup_type, field_name):
# http://www.postgresql.org/docs/8.0/static/functions-datetime.html#FUNCTIONS-DATETIME-TRUNC
return "DATE_TRUNC('%s', %s)" % (lookup_type, field_name)
def deferrable_sql(self):
return " DEFERRABLE INITIALLY DEFERRED"
def last_insert_id(self, cursor, table_name, pk_name):
cursor.execute("SELECT CURRVAL('\"%s_%s_seq\"')" % (table_name, pk_name))
return cursor.fetchone()[0]
def quote_name(self, name):
if name.startswith('"') and name.endswith('"'):
return name # Quoting once is enough.
return '"%s"' % name
def sql_flush(self, style, tables, sequences):
if tables:
if postgres_version[0] >= 8 and postgres_version[1] >= 1:
# Postgres 8.1+ can do 'TRUNCATE x, y, z...;'. In fact, it *has to*
# in order to be able to truncate tables referenced by a foreign
# key in any other table. The result is a single SQL TRUNCATE
# statement.
sql = ['%s %s;' % \
(style.SQL_KEYWORD('TRUNCATE'),
style.SQL_FIELD(', '.join([self.quote_name(table) for table in tables]))
)]
else:
# Older versions of Postgres can't do TRUNCATE in a single call, so
# they must use a simple delete.
sql = ['%s %s %s;' % \
(style.SQL_KEYWORD('DELETE'),
style.SQL_KEYWORD('FROM'),
style.SQL_FIELD(self.quote_name(table))
) for table in tables]
# 'ALTER SEQUENCE sequence_name RESTART WITH 1;'... style SQL statements
# to reset sequence indices
for sequence_info in sequences:
table_name = sequence_info['table']
column_name = sequence_info['column']
if column_name and len(column_name)>0:
# sequence name in this case will be <table>_<column>_seq
sql.append("%s %s %s %s %s %s;" % \
(style.SQL_KEYWORD('ALTER'),
style.SQL_KEYWORD('SEQUENCE'),
style.SQL_FIELD(self.quote_name('%s_%s_seq' % (table_name, column_name))),
style.SQL_KEYWORD('RESTART'),
style.SQL_KEYWORD('WITH'),
style.SQL_FIELD('1')
)
)
else:
# sequence name in this case will be <table>_id_seq
sql.append("%s %s %s %s %s %s;" % \
(style.SQL_KEYWORD('ALTER'),
style.SQL_KEYWORD('SEQUENCE'),
style.SQL_FIELD(self.quote_name('%s_id_seq' % table_name)),
style.SQL_KEYWORD('RESTART'),
style.SQL_KEYWORD('WITH'),
style.SQL_FIELD('1')
)
)
return sql
else:
return []
def sequence_reset_sql(self, style, model_list):
from django.db import models
output = []
qn = self.quote_name
for model in model_list:
# Use `coalesce` to set the sequence for each model to the max pk value if there are records,
# or 1 if there are none. Set the `is_called` property (the third argument to `setval`) to true
# if there are records (as the max pk value is already in use), otherwise set it to false.
for f in model._meta.fields:
if isinstance(f, models.AutoField):
output.append("%s setval('%s', coalesce(max(%s), 1), max(%s) %s null) %s %s;" % \
(style.SQL_KEYWORD('SELECT'),
style.SQL_FIELD(qn('%s_%s_seq' % (model._meta.db_table, f.column))),
style.SQL_FIELD(qn(f.column)),
style.SQL_FIELD(qn(f.column)),
style.SQL_KEYWORD('IS NOT'),
style.SQL_KEYWORD('FROM'),
style.SQL_TABLE(qn(model._meta.db_table))))
break # Only one AutoField is allowed per model, so don't bother continuing.
for f in model._meta.many_to_many:
output.append("%s setval('%s', coalesce(max(%s), 1), max(%s) %s null) %s %s;" % \
(style.SQL_KEYWORD('SELECT'),
style.SQL_FIELD(qn('%s_id_seq' % f.m2m_db_table())),
style.SQL_FIELD(qn('id')),
style.SQL_FIELD(qn('id')),
style.SQL_KEYWORD('IS NOT'),
style.SQL_KEYWORD('FROM'),
style.SQL_TABLE(f.m2m_db_table())))
return output
class DatabaseWrapper(BaseDatabaseWrapper):
ops = DatabaseOperations()
def _cursor(self, settings):
set_tz = False
if self.connection is None:
set_tz = True
if settings.DATABASE_NAME == '':
from django.core.exceptions import ImproperlyConfigured
raise ImproperlyConfigured, "You need to specify DATABASE_NAME in your Django settings file."
conn_string = "dbname=%s" % settings.DATABASE_NAME
if settings.DATABASE_USER:
conn_string = "user=%s %s" % (settings.DATABASE_USER, conn_string)
if settings.DATABASE_PASSWORD:
conn_string += " password='%s'" % settings.DATABASE_PASSWORD
if settings.DATABASE_HOST:
conn_string += " host=%s" % settings.DATABASE_HOST
if settings.DATABASE_PORT:
conn_string += " port=%s" % settings.DATABASE_PORT
self.connection = Database.connect(conn_string, **self.options)
self.connection.set_isolation_level(1) # make transactions transparent to all cursors
cursor = self.connection.cursor()
if set_tz:
cursor.execute("SET TIME ZONE %s", [settings.TIME_ZONE])
cursor.execute("SET client_encoding to 'UNICODE'")
cursor = UnicodeCursorWrapper(cursor, 'utf-8')
global postgres_version
if not postgres_version:
cursor.execute("SELECT version()")
postgres_version = [int(val) for val in cursor.fetchone()[0].split()[1].split('.')]
return cursor
allows_group_by_ordinal = True
allows_unique_and_pk = True
autoindexes_primary_keys = True
needs_datetime_string_cast = True
needs_upper_for_iops = False
supports_constraints = True
supports_tablespaces = False
uses_case_insensitive_names = False
def dictfetchone(cursor):
"Returns a row from the cursor as a dict"
return cursor.dictfetchone()
def dictfetchmany(cursor, number):
"Returns a certain number of rows from a cursor as a dict"
return cursor.dictfetchmany(number)
def dictfetchall(cursor):
"Returns all rows from a cursor as a dict"
return cursor.dictfetchall()
def typecast_string(s):
"""
Cast all returned strings to unicode strings.
"""
if not s and not isinstance(s, str):
return s
return smart_unicode(s)
# Register these custom typecasts, because Django expects dates/times to be
# in Python's native (standard-library) datetime/time format, whereas psycopg
# use mx.DateTime by default.
try:
Database.register_type(Database.new_type((1082,), "DATE", util.typecast_date))
except AttributeError:
raise Exception, "You appear to be using psycopg version 2. Set your DATABASE_ENGINE to 'postgresql_psycopg2' instead of 'postgresql'."
Database.register_type(Database.new_type((1083,1266), "TIME", util.typecast_time))
Database.register_type(Database.new_type((1114,1184), "TIMESTAMP", util.typecast_timestamp))
Database.register_type(Database.new_type((16,), "BOOLEAN", util.typecast_boolean))
Database.register_type(Database.new_type((1700,), "NUMERIC", util.typecast_decimal))
Database.register_type(Database.new_type(Database.types[1043].values, 'STRING', typecast_string))
OPERATOR_MAPPING = {
'exact': '= %s',
'iexact': 'ILIKE %s',
'contains': 'LIKE %s',
'icontains': 'ILIKE %s',
'regex': '~ %s',
'iregex': '~* %s',
'gt': '> %s',
'gte': '>= %s',
'lt': '< %s',
'lte': '<= %s',
'startswith': 'LIKE %s',
'endswith': 'LIKE %s',
'istartswith': 'ILIKE %s',
'iendswith': 'ILIKE %s',
}