129 lines
4.0 KiB
Python
129 lines
4.0 KiB
Python
try:
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# Only exists in Python 2.4+
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from threading import local
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except ImportError:
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# Import copy of _thread_local.py from Python 2.4
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from django.utils._threading_local import local
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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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def __init__(self, **kwargs):
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self.connection = None
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self.queries = []
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self.options = kwargs
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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 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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from django.conf import settings
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cursor = self._cursor(settings)
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if 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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from django.db.backends import util
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return util.CursorDebugWrapper(cursor, self)
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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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def autoinc_sql(self, table):
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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_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. This
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method should return None if no casting is necessary.
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"""
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return None
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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 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_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 limit_offset_sql(self, limit, offset=None):
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"""
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Returns a LIMIT/OFFSET SQL clause, given a limit and optional offset.
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"""
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# 'LIMIT 40 OFFSET 20'
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sql = "LIMIT %s" % limit
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if offset and offset != 0:
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sql += " OFFSET %s" % offset
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return sql
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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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