709 lines
24 KiB
Python
709 lines
24 KiB
Python
import decimal
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from threading import local
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from django.conf import settings
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from django.db import DEFAULT_DB_ALIAS
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from django.db.backends import util
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from django.utils import datetime_safe
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from django.utils.importlib import import_module
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class BaseDatabaseWrapper(local):
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"""
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Represents a database connection.
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"""
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ops = None
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vendor = 'unknown'
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def __init__(self, settings_dict, alias=DEFAULT_DB_ALIAS):
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# `settings_dict` should be a dictionary containing keys such as
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# NAME, USER, etc. It's called `settings_dict` instead of `settings`
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# to disambiguate it from Django settings modules.
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self.connection = None
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self.queries = []
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self.settings_dict = settings_dict
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self.alias = alias
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self.use_debug_cursor = None
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# Transaction related attributes
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self.transaction_state = []
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self.savepoint_state = 0
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self.dirty = None
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def __eq__(self, other):
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return self.alias == other.alias
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def __ne__(self, other):
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return not self == other
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def _commit(self):
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if self.connection is not None:
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return self.connection.commit()
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def _rollback(self):
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if self.connection is not None:
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return self.connection.rollback()
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def _enter_transaction_management(self, managed):
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"""
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A hook for backend-specific changes required when entering manual
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transaction handling.
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"""
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pass
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def _leave_transaction_management(self, managed):
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"""
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A hook for backend-specific changes required when leaving manual
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transaction handling. Will usually be implemented only when
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_enter_transaction_management() is also required.
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"""
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pass
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def _savepoint(self, sid):
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if not self.features.uses_savepoints:
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return
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self.cursor().execute(self.ops.savepoint_create_sql(sid))
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def _savepoint_rollback(self, sid):
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if not self.features.uses_savepoints:
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return
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self.cursor().execute(self.ops.savepoint_rollback_sql(sid))
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def _savepoint_commit(self, sid):
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if not self.features.uses_savepoints:
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return
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self.cursor().execute(self.ops.savepoint_commit_sql(sid))
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def close(self):
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if self.connection is not None:
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self.connection.close()
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self.connection = None
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def cursor(self):
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cursor = self._cursor()
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if (self.use_debug_cursor or
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(self.use_debug_cursor is None and settings.DEBUG)):
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return self.make_debug_cursor(cursor)
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return cursor
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def make_debug_cursor(self, cursor):
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return util.CursorDebugWrapper(cursor, self)
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class BaseDatabaseFeatures(object):
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allows_group_by_pk = False
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# True if django.db.backend.utils.typecast_timestamp is used on values
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# returned from dates() calls.
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needs_datetime_string_cast = True
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empty_fetchmany_value = []
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update_can_self_select = True
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# Does the backend distinguish between '' and None?
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interprets_empty_strings_as_nulls = False
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can_use_chunked_reads = True
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can_return_id_from_insert = False
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uses_autocommit = False
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uses_savepoints = False
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# If True, don't use integer foreign keys referring to, e.g., positive
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# integer primary keys.
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related_fields_match_type = False
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allow_sliced_subqueries = True
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# Does the default test database allow multiple connections?
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# Usually an indication that the test database is in-memory
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test_db_allows_multiple_connections = True
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# Can an object be saved without an explicit primary key?
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supports_unspecified_pk = False
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# Can a fixture contain forward references? i.e., are
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# FK constraints checked at the end of transaction, or
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# at the end of each save operation?
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supports_forward_references = True
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# Does a dirty transaction need to be rolled back
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# before the cursor can be used again?
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requires_rollback_on_dirty_transaction = False
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# Does the backend allow very long model names without error?
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supports_long_model_names = True
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# Is there a REAL datatype in addition to floats/doubles?
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has_real_datatype = False
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supports_subqueries_in_group_by = True
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supports_bitwise_or = True
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# Do time/datetime fields have microsecond precision?
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supports_microsecond_precision = True
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# Does the __regex lookup support backreferencing and grouping?
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supports_regex_backreferencing = True
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# Can date/datetime lookups be performed using a string?
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supports_date_lookup_using_string = True
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# Can datetimes with timezones be used?
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supports_timezones = True
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# When performing a GROUP BY, is an ORDER BY NULL required
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# to remove any ordering?
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requires_explicit_null_ordering_when_grouping = False
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# Is there a 1000 item limit on query parameters?
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supports_1000_query_parameters = True
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# Can an object have a primary key of 0? MySQL says No.
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allows_primary_key_0 = True
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# Do we need to NULL a ForeignKey out, or can the constraint check be
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# deferred
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can_defer_constraint_checks = False
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# date_interval_sql can properly handle mixed Date/DateTime fields and timedeltas
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supports_mixed_date_datetime_comparisons = True
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# Features that need to be confirmed at runtime
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# Cache whether the confirmation has been performed.
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_confirmed = False
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supports_transactions = None
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supports_stddev = None
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def __init__(self, connection):
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self.connection = connection
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def confirm(self):
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"Perform manual checks of any database features that might vary between installs"
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self._confirmed = True
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self.supports_transactions = self._supports_transactions()
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self.supports_stddev = self._supports_stddev()
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def _supports_transactions(self):
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"Confirm support for transactions"
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cursor = self.connection.cursor()
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cursor.execute('CREATE TABLE ROLLBACK_TEST (X INT)')
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self.connection._commit()
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cursor.execute('INSERT INTO ROLLBACK_TEST (X) VALUES (8)')
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self.connection._rollback()
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cursor.execute('SELECT COUNT(X) FROM ROLLBACK_TEST')
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count, = cursor.fetchone()
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cursor.execute('DROP TABLE ROLLBACK_TEST')
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self.connection._commit()
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return count == 0
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def _supports_stddev(self):
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"Confirm support for STDDEV and related stats functions"
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class StdDevPop(object):
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sql_function = 'STDDEV_POP'
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try:
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self.connection.ops.check_aggregate_support(StdDevPop())
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except NotImplementedError:
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self.supports_stddev = False
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class BaseDatabaseOperations(object):
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"""
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This class encapsulates all backend-specific differences, such as the way
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a backend performs ordering or calculates the ID of a recently-inserted
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row.
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"""
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compiler_module = "django.db.models.sql.compiler"
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def __init__(self):
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self._cache = None
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def autoinc_sql(self, table, column):
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"""
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Returns any SQL needed to support auto-incrementing primary keys, or
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None if no SQL is necessary.
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This SQL is executed when a table is created.
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"""
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return None
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def date_extract_sql(self, lookup_type, field_name):
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"""
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Given a lookup_type of 'year', 'month' or 'day', returns the SQL that
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extracts a value from the given date field field_name.
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"""
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raise NotImplementedError()
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def date_interval_sql(self, sql, connector, timedelta):
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"""
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Implements the date interval functionality for expressions
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"""
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raise NotImplementedError()
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def date_trunc_sql(self, lookup_type, field_name):
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"""
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Given a lookup_type of 'year', 'month' or 'day', returns the SQL that
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truncates the given date field field_name to a DATE object with only
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the given specificity.
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"""
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raise NotImplementedError()
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def datetime_cast_sql(self):
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"""
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Returns the SQL necessary to cast a datetime value so that it will be
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retrieved as a Python datetime object instead of a string.
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This SQL should include a '%s' in place of the field's name.
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"""
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return "%s"
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def deferrable_sql(self):
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"""
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Returns the SQL necessary to make a constraint "initially deferred"
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during a CREATE TABLE statement.
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"""
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return ''
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def drop_foreignkey_sql(self):
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"""
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Returns the SQL command that drops a foreign key.
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"""
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return "DROP CONSTRAINT"
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def drop_sequence_sql(self, table):
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"""
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Returns any SQL necessary to drop the sequence for the given table.
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Returns None if no SQL is necessary.
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"""
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return None
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def fetch_returned_insert_id(self, cursor):
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"""
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Given a cursor object that has just performed an INSERT...RETURNING
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statement into a table that has an auto-incrementing ID, returns the
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newly created ID.
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"""
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return cursor.fetchone()[0]
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def field_cast_sql(self, db_type):
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"""
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Given a column type (e.g. 'BLOB', 'VARCHAR'), returns the SQL necessary
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to cast it before using it in a WHERE statement. Note that the
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resulting string should contain a '%s' placeholder for the column being
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searched against.
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"""
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return '%s'
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def force_no_ordering(self):
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"""
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Returns a list used in the "ORDER BY" clause to force no ordering at
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all. Returning an empty list means that nothing will be included in the
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ordering.
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"""
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return []
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def fulltext_search_sql(self, field_name):
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"""
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Returns the SQL WHERE clause to use in order to perform a full-text
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search of the given field_name. Note that the resulting string should
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contain a '%s' placeholder for the value being searched against.
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"""
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raise NotImplementedError('Full-text search is not implemented for this database backend')
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def last_executed_query(self, cursor, sql, params):
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"""
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Returns a string of the query last executed by the given cursor, with
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placeholders replaced with actual values.
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`sql` is the raw query containing placeholders, and `params` is the
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sequence of parameters. These are used by default, but this method
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exists for database backends to provide a better implementation
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according to their own quoting schemes.
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"""
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from django.utils.encoding import smart_unicode, force_unicode
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# Convert params to contain Unicode values.
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to_unicode = lambda s: force_unicode(s, strings_only=True, errors='replace')
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if isinstance(params, (list, tuple)):
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u_params = tuple([to_unicode(val) for val in params])
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else:
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u_params = dict([(to_unicode(k), to_unicode(v)) for k, v in params.items()])
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return smart_unicode(sql) % u_params
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def last_insert_id(self, cursor, table_name, pk_name):
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"""
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Given a cursor object that has just performed an INSERT statement into
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a table that has an auto-incrementing ID, returns the newly created ID.
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This method also receives the table name and the name of the primary-key
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column.
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"""
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return cursor.lastrowid
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def lookup_cast(self, lookup_type):
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"""
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Returns the string to use in a query when performing lookups
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("contains", "like", etc). The resulting string should contain a '%s'
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placeholder for the column being searched against.
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"""
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return "%s"
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def max_in_list_size(self):
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"""
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Returns the maximum number of items that can be passed in a single 'IN'
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list condition, or None if the backend does not impose a limit.
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"""
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return None
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def max_name_length(self):
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"""
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Returns the maximum length of table and column names, or None if there
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is no limit.
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"""
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return None
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def no_limit_value(self):
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"""
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Returns the value to use for the LIMIT when we are wanting "LIMIT
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infinity". Returns None if the limit clause can be omitted in this case.
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"""
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raise NotImplementedError
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def pk_default_value(self):
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"""
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Returns the value to use during an INSERT statement to specify that
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the field should use its default value.
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"""
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return 'DEFAULT'
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def process_clob(self, value):
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"""
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Returns the value of a CLOB column, for backends that return a locator
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object that requires additional processing.
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"""
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return value
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def return_insert_id(self):
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"""
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For backends that support returning the last insert ID as part
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of an insert query, this method returns the SQL and params to
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append to the INSERT query. The returned fragment should
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contain a format string to hold the appropriate column.
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"""
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pass
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def compiler(self, compiler_name):
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"""
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Returns the SQLCompiler class corresponding to the given name,
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in the namespace corresponding to the `compiler_module` attribute
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on this backend.
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"""
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if self._cache is None:
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self._cache = import_module(self.compiler_module)
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return getattr(self._cache, compiler_name)
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def quote_name(self, name):
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"""
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Returns a quoted version of the given table, index or column name. Does
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not quote the given name if it's already been quoted.
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"""
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raise NotImplementedError()
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def random_function_sql(self):
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"""
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Returns a SQL expression that returns a random value.
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"""
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return 'RANDOM()'
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def regex_lookup(self, lookup_type):
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"""
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Returns the string to use in a query when performing regular expression
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lookups (using "regex" or "iregex"). The resulting string should
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contain a '%s' placeholder for the column being searched against.
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If the feature is not supported (or part of it is not supported), a
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NotImplementedError exception can be raised.
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"""
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raise NotImplementedError
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def savepoint_create_sql(self, sid):
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"""
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Returns the SQL for starting a new savepoint. Only required if the
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"uses_savepoints" feature is True. The "sid" parameter is a string
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for the savepoint id.
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"""
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raise NotImplementedError
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def savepoint_commit_sql(self, sid):
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"""
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Returns the SQL for committing the given savepoint.
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"""
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raise NotImplementedError
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def savepoint_rollback_sql(self, sid):
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"""
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Returns the SQL for rolling back the given savepoint.
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"""
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raise NotImplementedError
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def sql_flush(self, style, tables, sequences):
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"""
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Returns a list of SQL statements required to remove all data from
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the given database tables (without actually removing the tables
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themselves).
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The `style` argument is a Style object as returned by either
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color_style() or no_style() in django.core.management.color.
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"""
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raise NotImplementedError()
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def sequence_reset_sql(self, style, model_list):
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"""
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Returns a list of the SQL statements required to reset sequences for
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the given models.
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The `style` argument is a Style object as returned by either
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color_style() or no_style() in django.core.management.color.
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"""
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return [] # No sequence reset required by default.
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def start_transaction_sql(self):
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"""
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Returns the SQL statement required to start a transaction.
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"""
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return "BEGIN;"
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def end_transaction_sql(self, success=True):
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if not success:
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return "ROLLBACK;"
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return "COMMIT;"
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def tablespace_sql(self, tablespace, inline=False):
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"""
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Returns the SQL that will be appended to tables or rows to define
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a tablespace. Returns '' if the backend doesn't use tablespaces.
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"""
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return ''
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def prep_for_like_query(self, x):
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"""Prepares a value for use in a LIKE query."""
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from django.utils.encoding import smart_unicode
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return smart_unicode(x).replace("\\", "\\\\").replace("%", "\%").replace("_", "\_")
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# Same as prep_for_like_query(), but called for "iexact" matches, which
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# need not necessarily be implemented using "LIKE" in the backend.
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prep_for_iexact_query = prep_for_like_query
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def value_to_db_date(self, value):
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"""
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Transform a date value to an object compatible with what is expected
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by the backend driver for date columns.
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"""
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if value is None:
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return None
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return datetime_safe.new_date(value).strftime('%Y-%m-%d')
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def value_to_db_datetime(self, value):
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"""
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Transform a datetime value to an object compatible with what is expected
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by the backend driver for datetime columns.
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"""
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if value is None:
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return None
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return unicode(value)
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def value_to_db_time(self, value):
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"""
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Transform a datetime value to an object compatible with what is expected
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by the backend driver for time columns.
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"""
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if value is None:
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return None
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return unicode(value)
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def value_to_db_decimal(self, value, max_digits, decimal_places):
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"""
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Transform a decimal.Decimal value to an object compatible with what is
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expected by the backend driver for decimal (numeric) columns.
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"""
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if value is None:
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return None
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return util.format_number(value, max_digits, decimal_places)
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def year_lookup_bounds(self, value):
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"""
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Returns a two-elements list with the lower and upper bound to be used
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with a BETWEEN operator to query a field value using a year lookup
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`value` is an int, containing the looked-up year.
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"""
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first = '%s-01-01 00:00:00'
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second = '%s-12-31 23:59:59.999999'
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return [first % value, second % value]
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def year_lookup_bounds_for_date_field(self, value):
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"""
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Returns a two-elements list with the lower and upper bound to be used
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with a BETWEEN operator to query a DateField value using a year lookup
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`value` is an int, containing the looked-up year.
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By default, it just calls `self.year_lookup_bounds`. Some backends need
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this hook because on their DB date fields can't be compared to values
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which include a time part.
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"""
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return self.year_lookup_bounds(value)
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def convert_values(self, value, field):
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"""Coerce the value returned by the database backend into a consistent type that
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is compatible with the field type.
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"""
|
|
internal_type = field.get_internal_type()
|
|
if internal_type == 'DecimalField':
|
|
return value
|
|
elif internal_type and internal_type.endswith('IntegerField') or internal_type == 'AutoField':
|
|
return int(value)
|
|
elif internal_type in ('DateField', 'DateTimeField', 'TimeField'):
|
|
return value
|
|
# No field, or the field isn't known to be a decimal or integer
|
|
# Default to a float
|
|
return float(value)
|
|
|
|
def check_aggregate_support(self, aggregate_func):
|
|
"""Check that the backend supports the provided aggregate
|
|
|
|
This is used on specific backends to rule out known aggregates
|
|
that are known to have faulty implementations. If the named
|
|
aggregate function has a known problem, the backend should
|
|
raise NotImplemented.
|
|
"""
|
|
pass
|
|
|
|
def combine_expression(self, connector, sub_expressions):
|
|
"""Combine a list of subexpressions into a single expression, using
|
|
the provided connecting operator. This is required because operators
|
|
can vary between backends (e.g., Oracle with %% and &) and between
|
|
subexpression types (e.g., date expressions)
|
|
"""
|
|
conn = ' %s ' % connector
|
|
return conn.join(sub_expressions)
|
|
|
|
class BaseDatabaseIntrospection(object):
|
|
"""
|
|
This class encapsulates all backend-specific introspection utilities
|
|
"""
|
|
data_types_reverse = {}
|
|
|
|
def __init__(self, connection):
|
|
self.connection = connection
|
|
|
|
def get_field_type(self, data_type, description):
|
|
"""Hook for a database backend to use the cursor description to
|
|
match a Django field type to a database column.
|
|
|
|
For Oracle, the column data_type on its own is insufficient to
|
|
distinguish between a FloatField and IntegerField, for example."""
|
|
return self.data_types_reverse[data_type]
|
|
|
|
def table_name_converter(self, name):
|
|
"""Apply a conversion to the name for the purposes of comparison.
|
|
|
|
The default table name converter is for case sensitive comparison.
|
|
"""
|
|
return name
|
|
|
|
def table_names(self):
|
|
"Returns a list of names of all tables that exist in the database."
|
|
cursor = self.connection.cursor()
|
|
return self.get_table_list(cursor)
|
|
|
|
def django_table_names(self, only_existing=False):
|
|
"""
|
|
Returns a list of all table names that have associated Django models and
|
|
are in INSTALLED_APPS.
|
|
|
|
If only_existing is True, the resulting list will only include the tables
|
|
that actually exist in the database.
|
|
"""
|
|
from django.db import models, router
|
|
tables = set()
|
|
for app in models.get_apps():
|
|
for model in models.get_models(app):
|
|
if not model._meta.managed:
|
|
continue
|
|
if not router.allow_syncdb(self.connection.alias, model):
|
|
continue
|
|
tables.add(model._meta.db_table)
|
|
tables.update([f.m2m_db_table() for f in model._meta.local_many_to_many])
|
|
if only_existing:
|
|
existing_tables = self.table_names()
|
|
tables = [
|
|
t
|
|
for t in tables
|
|
if self.table_name_converter(t) in existing_tables
|
|
]
|
|
return tables
|
|
|
|
def installed_models(self, tables):
|
|
"Returns a set of all models represented by the provided list of table names."
|
|
from django.db import models, router
|
|
all_models = []
|
|
for app in models.get_apps():
|
|
for model in models.get_models(app):
|
|
if router.allow_syncdb(self.connection.alias, model):
|
|
all_models.append(model)
|
|
tables = map(self.table_name_converter, tables)
|
|
return set([
|
|
m for m in all_models
|
|
if self.table_name_converter(m._meta.db_table) in tables
|
|
])
|
|
|
|
def sequence_list(self):
|
|
"Returns a list of information about all DB sequences for all models in all apps."
|
|
from django.db import models, router
|
|
|
|
apps = models.get_apps()
|
|
sequence_list = []
|
|
|
|
for app in apps:
|
|
for model in models.get_models(app):
|
|
if not model._meta.managed:
|
|
continue
|
|
if not router.allow_syncdb(self.connection.alias, model):
|
|
continue
|
|
for f in model._meta.local_fields:
|
|
if isinstance(f, models.AutoField):
|
|
sequence_list.append({'table': model._meta.db_table, 'column': f.column})
|
|
break # Only one AutoField is allowed per model, so don't bother continuing.
|
|
|
|
for f in model._meta.local_many_to_many:
|
|
# If this is an m2m using an intermediate table,
|
|
# we don't need to reset the sequence.
|
|
if f.rel.through is None:
|
|
sequence_list.append({'table': f.m2m_db_table(), 'column': None})
|
|
|
|
return sequence_list
|
|
|
|
class BaseDatabaseClient(object):
|
|
"""
|
|
This class encapsulates all backend-specific methods for opening a
|
|
client shell.
|
|
"""
|
|
# This should be a string representing the name of the executable
|
|
# (e.g., "psql"). Subclasses must override this.
|
|
executable_name = None
|
|
|
|
def __init__(self, connection):
|
|
# connection is an instance of BaseDatabaseWrapper.
|
|
self.connection = connection
|
|
|
|
def runshell(self):
|
|
raise NotImplementedError()
|
|
|
|
class BaseDatabaseValidation(object):
|
|
"""
|
|
This class encapsualtes all backend-specific model validation.
|
|
"""
|
|
def __init__(self, connection):
|
|
self.connection = connection
|
|
|
|
def validate_field(self, errors, opts, f):
|
|
"By default, there is no backend-specific validation"
|
|
pass
|