# Copyright 2009 10gen, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Tools for manipulating DBRefs (references to MongoDB documents)."""
from bson.son import SON
from txmongo.collection import Collection
import types
[docs]class DBRef(object):
"""A reference to a document stored in a Mongo database.
"""
def __init__(self, collection, id, database=None):
"""Initialize a new DBRef.
Raises TypeError if collection or database is not an instance of
(str, unicode). `database` is optional and allows references to
documents to work across databases.
:Parameters:
- `collection`: name of the collection the document is stored in
- `id`: the value of the document's _id field
- `database` (optional): name of the database to reference
.. versionadded:: 1.1.1
The `database` parameter.
"""
if isinstance(collection, Collection):
collection = collection._collection_name
if not isinstance(collection, types.StringTypes):
raise TypeError("collection must be an instance of (str, unicode)")
if not isinstance(database, (types.StringTypes, types.NoneType)):
raise TypeError("database must be an instance of (str, unicode)")
self.__collection = collection
self.__id = id
self.__database = database
def collection(self):
"""Get the name of this DBRef's collection as unicode.
"""
return self.__collection
collection = property(collection)
def id(self):
"""Get this DBRef's _id.
"""
return self.__id
id = property(id)
def database(self):
"""Get the name of this DBRef's database.
Returns None if this DBRef doesn't specify a database.
.. versionadded:: 1.1.1
"""
return self.__database
database = property(database)
[docs] def as_doc(self):
"""Get the SON document representation of this DBRef.
Generally not needed by application developers
"""
doc = SON([("$ref", self.collection),
("$id", self.id)])
if self.database is not None:
doc["$db"] = self.database
return doc
def __repr__(self):
if self.database is None:
return "DBRef(%s, %r)" % (self.collection, self.id)
return "DBRef(%s, %r, %s)" % (self.collection, self.id, self.database)
def __cmp__(self, other):
if isinstance(other, DBRef):
return cmp([self.__database, self.__collection, self.__id],
[other.__database, other.__collection, other.__id])
return NotImplemented
def __hash__(self):
"""Get a hash value for this :class:`DBRef`.
.. versionadded:: 1.1
"""
return hash((self.__collection, self.__id, self.__database))