500 lines
17 KiB
Python
500 lines
17 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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try:
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set
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except NameError:
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# Python 2.3 compat
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from sets import Set as set
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try:
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import decimal
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except ImportError:
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# Python 2.3 fallback
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from django.utils import _decimal as decimal
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from django.db.backends import util
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from django.utils import datetime_safe
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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 _savepoint(self, sid):
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if not self.features.uses_savepoints:
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return
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self.connection.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.connection.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.connection.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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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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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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uses_custom_query_class = False
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empty_fetchmany_value = []
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update_can_self_select = True
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interprets_empty_strings_as_nulls = False
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can_use_chunked_reads = True
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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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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, 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_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 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)
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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_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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# FIXME: API may need to change once Oracle backend is repaired.
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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 query_class(self, DefaultQueryClass):
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"""
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Given the default Query class, returns a custom Query class
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to use for this backend. Returns None if a custom Query isn't used.
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See also BaseDatabaseFeatures.uses_custom_query_class, which regulates
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whether this method is called at all.
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"""
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return None
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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 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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"""
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internal_type = field.get_internal_type()
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if internal_type == 'DecimalField':
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return value
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elif internal_type and internal_type.endswith('IntegerField') or internal_type == 'AutoField':
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return int(value)
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elif internal_type in ('DateField', 'DateTimeField', 'TimeField'):
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return value
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# No field, or the field isn't known to be a decimal or integer
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# Default to a float
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return float(value)
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def check_aggregate_support(self, aggregate_func):
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"""Check that the backend supports the provided aggregate
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This is used on specific backends to rule out known aggregates
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that are known to have faulty implementations. If the named
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aggregate function has a known problem, the backend should
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raise NotImplemented.
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"""
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pass
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class BaseDatabaseIntrospection(object):
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"""
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This class encapsulates all backend-specific introspection utilities
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"""
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data_types_reverse = {}
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def __init__(self, connection):
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self.connection = connection
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def table_name_converter(self, name):
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"""Apply a conversion to the name for the purposes of comparison.
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The default table name converter is for case sensitive comparison.
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"""
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return name
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def table_names(self):
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"Returns a list of names of all tables that exist in the database."
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cursor = self.connection.cursor()
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return self.get_table_list(cursor)
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def django_table_names(self, only_existing=False):
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"""
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Returns a list of all table names that have associated Django models and
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are in INSTALLED_APPS.
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If only_existing is True, the resulting list will only include the tables
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that actually exist in the database.
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"""
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from django.db import models
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tables = set()
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for app in models.get_apps():
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for model in models.get_models(app):
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tables.add(model._meta.db_table)
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tables.update([f.m2m_db_table() for f in model._meta.local_many_to_many])
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if only_existing:
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tables = [t for t in tables if self.table_name_converter(t) in self.table_names()]
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return tables
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def installed_models(self, tables):
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"Returns a set of all models represented by the provided list of table names."
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from django.db import models
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all_models = []
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for app in models.get_apps():
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for model in models.get_models(app):
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all_models.append(model)
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return set([m for m in all_models
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if self.table_name_converter(m._meta.db_table) in map(self.table_name_converter, tables)
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])
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def sequence_list(self):
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"Returns a list of information about all DB sequences for all models in all apps."
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from django.db import models
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apps = models.get_apps()
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sequence_list = []
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for app in apps:
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for model in models.get_models(app):
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for f in model._meta.local_fields:
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if isinstance(f, models.AutoField):
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sequence_list.append({'table': model._meta.db_table, 'column': f.column})
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break # Only one AutoField is allowed per model, so don't bother continuing.
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for f in model._meta.local_many_to_many:
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sequence_list.append({'table': f.m2m_db_table(), 'column': None})
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return sequence_list
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class BaseDatabaseClient(object):
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"""
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This class encapsulates all backend-specific methods for opening a
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client shell.
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"""
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# This should be a string representing the name of the executable
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# (e.g., "psql"). Subclasses must override this.
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executable_name = None
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def runshell(self):
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raise NotImplementedError()
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class BaseDatabaseValidation(object):
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"""
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This class encapsualtes all backend-specific model validation.
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"""
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def validate_field(self, errors, opts, f):
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"By default, there is no backend-specific validation"
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pass
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