338 lines
13 KiB
Python
338 lines
13 KiB
Python
"""
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PostgreSQL database backend for Django.
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Requires psycopg 2: https://www.psycopg.org/
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"""
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import asyncio
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import threading
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import warnings
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from contextlib import contextmanager
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from django.conf import settings
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from django.core.exceptions import ImproperlyConfigured
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from django.db import DatabaseError as WrappedDatabaseError, connections
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from django.db.backends.base.base import BaseDatabaseWrapper
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from django.db.backends.utils import (
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CursorDebugWrapper as BaseCursorDebugWrapper,
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)
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from django.utils.asyncio import async_unsafe
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from django.utils.functional import cached_property
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from django.utils.safestring import SafeString
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from django.utils.version import get_version_tuple
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try:
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import psycopg2 as Database
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import psycopg2.extensions
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import psycopg2.extras
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except ImportError as e:
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raise ImproperlyConfigured("Error loading psycopg2 module: %s" % e)
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def psycopg2_version():
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version = psycopg2.__version__.split(' ', 1)[0]
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return get_version_tuple(version)
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PSYCOPG2_VERSION = psycopg2_version()
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if PSYCOPG2_VERSION < (2, 5, 4):
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raise ImproperlyConfigured("psycopg2_version 2.5.4 or newer is required; you have %s" % psycopg2.__version__)
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# Some of these import psycopg2, so import them after checking if it's installed.
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from .client import DatabaseClient # NOQA isort:skip
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from .creation import DatabaseCreation # NOQA isort:skip
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from .features import DatabaseFeatures # NOQA isort:skip
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from .introspection import DatabaseIntrospection # NOQA isort:skip
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from .operations import DatabaseOperations # NOQA isort:skip
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from .schema import DatabaseSchemaEditor # NOQA isort:skip
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psycopg2.extensions.register_adapter(SafeString, psycopg2.extensions.QuotedString)
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psycopg2.extras.register_uuid()
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# Register support for inet[] manually so we don't have to handle the Inet()
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# object on load all the time.
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INETARRAY_OID = 1041
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INETARRAY = psycopg2.extensions.new_array_type(
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(INETARRAY_OID,),
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'INETARRAY',
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psycopg2.extensions.UNICODE,
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)
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psycopg2.extensions.register_type(INETARRAY)
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class DatabaseWrapper(BaseDatabaseWrapper):
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vendor = 'postgresql'
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display_name = 'PostgreSQL'
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# This dictionary maps Field objects to their associated PostgreSQL column
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# types, as strings. Column-type strings can contain format strings; they'll
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# be interpolated against the values of Field.__dict__ before being output.
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# If a column type is set to None, it won't be included in the output.
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data_types = {
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'AutoField': 'serial',
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'BigAutoField': 'bigserial',
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'BinaryField': 'bytea',
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'BooleanField': 'boolean',
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'CharField': 'varchar(%(max_length)s)',
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'DateField': 'date',
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'DateTimeField': 'timestamp with time zone',
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'DecimalField': 'numeric(%(max_digits)s, %(decimal_places)s)',
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'DurationField': 'interval',
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'FileField': 'varchar(%(max_length)s)',
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'FilePathField': 'varchar(%(max_length)s)',
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'FloatField': 'double precision',
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'IntegerField': 'integer',
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'BigIntegerField': 'bigint',
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'IPAddressField': 'inet',
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'GenericIPAddressField': 'inet',
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'JSONField': 'jsonb',
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'NullBooleanField': 'boolean',
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'OneToOneField': 'integer',
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'PositiveBigIntegerField': 'bigint',
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'PositiveIntegerField': 'integer',
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'PositiveSmallIntegerField': 'smallint',
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'SlugField': 'varchar(%(max_length)s)',
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'SmallAutoField': 'smallserial',
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'SmallIntegerField': 'smallint',
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'TextField': 'text',
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'TimeField': 'time',
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'UUIDField': 'uuid',
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}
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data_type_check_constraints = {
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'PositiveBigIntegerField': '"%(column)s" >= 0',
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'PositiveIntegerField': '"%(column)s" >= 0',
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'PositiveSmallIntegerField': '"%(column)s" >= 0',
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}
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operators = {
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'exact': '= %s',
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'iexact': '= UPPER(%s)',
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'contains': 'LIKE %s',
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'icontains': 'LIKE UPPER(%s)',
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'regex': '~ %s',
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'iregex': '~* %s',
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'gt': '> %s',
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'gte': '>= %s',
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'lt': '< %s',
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'lte': '<= %s',
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'startswith': 'LIKE %s',
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'endswith': 'LIKE %s',
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'istartswith': 'LIKE UPPER(%s)',
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'iendswith': 'LIKE UPPER(%s)',
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}
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# The patterns below are used to generate SQL pattern lookup clauses when
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# the right-hand side of the lookup isn't a raw string (it might be an expression
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# or the result of a bilateral transformation).
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# In those cases, special characters for LIKE operators (e.g. \, *, _) should be
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# escaped on database side.
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#
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# Note: we use str.format() here for readability as '%' is used as a wildcard for
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# the LIKE operator.
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pattern_esc = r"REPLACE(REPLACE(REPLACE({}, E'\\', E'\\\\'), E'%%', E'\\%%'), E'_', E'\\_')"
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pattern_ops = {
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'contains': "LIKE '%%' || {} || '%%'",
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'icontains': "LIKE '%%' || UPPER({}) || '%%'",
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'startswith': "LIKE {} || '%%'",
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'istartswith': "LIKE UPPER({}) || '%%'",
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'endswith': "LIKE '%%' || {}",
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'iendswith': "LIKE '%%' || UPPER({})",
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}
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Database = Database
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SchemaEditorClass = DatabaseSchemaEditor
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# Classes instantiated in __init__().
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client_class = DatabaseClient
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creation_class = DatabaseCreation
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features_class = DatabaseFeatures
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introspection_class = DatabaseIntrospection
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ops_class = DatabaseOperations
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# PostgreSQL backend-specific attributes.
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_named_cursor_idx = 0
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def get_connection_params(self):
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settings_dict = self.settings_dict
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# None may be used to connect to the default 'postgres' db
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if settings_dict['NAME'] == '':
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raise ImproperlyConfigured(
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"settings.DATABASES is improperly configured. "
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"Please supply the NAME value.")
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if len(settings_dict['NAME'] or '') > self.ops.max_name_length():
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raise ImproperlyConfigured(
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"The database name '%s' (%d characters) is longer than "
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"PostgreSQL's limit of %d characters. Supply a shorter NAME "
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"in settings.DATABASES." % (
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settings_dict['NAME'],
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len(settings_dict['NAME']),
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self.ops.max_name_length(),
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)
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)
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conn_params = {
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'database': settings_dict['NAME'] or 'postgres',
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**settings_dict['OPTIONS'],
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}
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conn_params.pop('isolation_level', None)
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if settings_dict['USER']:
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conn_params['user'] = settings_dict['USER']
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if settings_dict['PASSWORD']:
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conn_params['password'] = settings_dict['PASSWORD']
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if settings_dict['HOST']:
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conn_params['host'] = settings_dict['HOST']
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if settings_dict['PORT']:
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conn_params['port'] = settings_dict['PORT']
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return conn_params
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@async_unsafe
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def get_new_connection(self, conn_params):
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connection = Database.connect(**conn_params)
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# self.isolation_level must be set:
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# - after connecting to the database in order to obtain the database's
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# default when no value is explicitly specified in options.
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# - before calling _set_autocommit() because if autocommit is on, that
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# will set connection.isolation_level to ISOLATION_LEVEL_AUTOCOMMIT.
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options = self.settings_dict['OPTIONS']
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try:
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self.isolation_level = options['isolation_level']
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except KeyError:
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self.isolation_level = connection.isolation_level
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else:
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# Set the isolation level to the value from OPTIONS.
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if self.isolation_level != connection.isolation_level:
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connection.set_session(isolation_level=self.isolation_level)
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return connection
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def ensure_timezone(self):
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if self.connection is None:
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return False
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conn_timezone_name = self.connection.get_parameter_status('TimeZone')
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timezone_name = self.timezone_name
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if timezone_name and conn_timezone_name != timezone_name:
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with self.connection.cursor() as cursor:
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cursor.execute(self.ops.set_time_zone_sql(), [timezone_name])
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return True
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return False
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def init_connection_state(self):
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self.connection.set_client_encoding('UTF8')
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timezone_changed = self.ensure_timezone()
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if timezone_changed:
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# Commit after setting the time zone (see #17062)
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if not self.get_autocommit():
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self.connection.commit()
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@async_unsafe
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def create_cursor(self, name=None):
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if name:
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# In autocommit mode, the cursor will be used outside of a
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# transaction, hence use a holdable cursor.
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cursor = self.connection.cursor(name, scrollable=False, withhold=self.connection.autocommit)
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else:
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cursor = self.connection.cursor()
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cursor.tzinfo_factory = self.tzinfo_factory if settings.USE_TZ else None
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return cursor
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def tzinfo_factory(self, offset):
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return self.timezone
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@async_unsafe
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def chunked_cursor(self):
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self._named_cursor_idx += 1
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# Get the current async task
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# Note that right now this is behind @async_unsafe, so this is
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# unreachable, but in future we'll start loosening this restriction.
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# For now, it's here so that every use of "threading" is
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# also async-compatible.
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try:
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if hasattr(asyncio, 'current_task'):
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# Python 3.7 and up
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current_task = asyncio.current_task()
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else:
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# Python 3.6
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current_task = asyncio.Task.current_task()
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except RuntimeError:
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current_task = None
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# Current task can be none even if the current_task call didn't error
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if current_task:
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task_ident = str(id(current_task))
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else:
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task_ident = 'sync'
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# Use that and the thread ident to get a unique name
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return self._cursor(
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name='_django_curs_%d_%s_%d' % (
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# Avoid reusing name in other threads / tasks
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threading.current_thread().ident,
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task_ident,
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self._named_cursor_idx,
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)
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)
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def _set_autocommit(self, autocommit):
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with self.wrap_database_errors:
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self.connection.autocommit = autocommit
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def check_constraints(self, table_names=None):
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"""
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Check constraints by setting them to immediate. Return them to deferred
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afterward.
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"""
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with self.cursor() as cursor:
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cursor.execute('SET CONSTRAINTS ALL IMMEDIATE')
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cursor.execute('SET CONSTRAINTS ALL DEFERRED')
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def is_usable(self):
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try:
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# Use a psycopg cursor directly, bypassing Django's utilities.
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with self.connection.cursor() as cursor:
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cursor.execute('SELECT 1')
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except Database.Error:
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return False
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else:
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return True
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@contextmanager
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def _nodb_cursor(self):
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try:
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with super()._nodb_cursor() as cursor:
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yield cursor
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except (Database.DatabaseError, WrappedDatabaseError):
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warnings.warn(
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"Normally Django will use a connection to the 'postgres' database "
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"to avoid running initialization queries against the production "
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"database when it's not needed (for example, when running tests). "
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"Django was unable to create a connection to the 'postgres' database "
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"and will use the first PostgreSQL database instead.",
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RuntimeWarning
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)
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for connection in connections.all():
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if connection.vendor == 'postgresql' and connection.settings_dict['NAME'] != 'postgres':
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conn = self.__class__(
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{**self.settings_dict, 'NAME': connection.settings_dict['NAME']},
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alias=self.alias,
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)
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try:
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with conn.cursor() as cursor:
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yield cursor
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finally:
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conn.close()
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@cached_property
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def pg_version(self):
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with self.temporary_connection():
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return self.connection.server_version
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def make_debug_cursor(self, cursor):
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return CursorDebugWrapper(cursor, self)
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class CursorDebugWrapper(BaseCursorDebugWrapper):
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def copy_expert(self, sql, file, *args):
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with self.debug_sql(sql):
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return self.cursor.copy_expert(sql, file, *args)
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def copy_to(self, file, table, *args, **kwargs):
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with self.debug_sql(sql='COPY %s TO STDOUT' % table):
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return self.cursor.copy_to(file, table, *args, **kwargs)
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