# Copyright 2009-2012 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 copy import deepcopy
from bson.son import SON
class DBRef(object):
"""A reference to a document stored in MongoDB.
"""
def __init__(self, collection, id, database=None, _extra={}, **kwargs):
"""Initialize a new :class:`DBRef`.
Raises :class:`TypeError` if `collection` or `database` is not
an instance of :class:`basestring` (:class:`str` in python 3).
`database` is optional and allows references to documents to work
across databases. Any additional keyword arguments will create
additional fields in the resultant embedded document.
: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
- `**kwargs` (optional): additional keyword arguments will
create additional, custom fields
.. versionchanged:: 1.8
Now takes keyword arguments to specify additional fields.
.. versionadded:: 1.1.1
The `database` parameter.
.. mongodoc:: dbrefs
"""
if not isinstance(collection, str):
raise TypeError("collection must be an "
"instance of %s" % (str.__name__,))
if database is not None and not isinstance(database, str):
raise TypeError("database must be an "
"instance of %s" % (str.__name__,))
self.__collection = collection
self.__id = id
self.__database = database
kwargs.update(_extra)
self.__kwargs = kwargs
@property
def collection(self):
"""Get the name of this DBRef's collection as unicode.
"""
return self.__collection
@property
def id(self):
"""Get this DBRef's _id.
"""
return self.__id
@property
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
def __getattr__(self, key):
try:
return self.__kwargs[key]
except KeyError:
raise AttributeError(key)
# Have to provide __setstate__ to avoid
# infinite recursion since we override
# __getattr__.
def __setstate__(self, state):
self.__dict__.update(state)
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
doc.update(self.__kwargs)
return doc
def __repr__(self):
extra = "".join([", %s=%r" % (k, v)
for k, v in self.__kwargs.items()])
if self.database is None:
return "DBRef(%r, %r%s)" % (self.collection, self.id, extra)
return "DBRef(%r, %r, %r%s)" % (self.collection, self.id,
self.database, extra)
def __eq__(self, other):
if isinstance(other, DBRef):
us = (self.__database, self.__collection,
self.__id, self.__kwargs)
them = (other.__database, other.__collection,
other.__id, other.__kwargs)
return us == them
return NotImplemented
def __ne__(self, other):
return not self == other
def __hash__(self):
"""Get a hash value for this :class:`DBRef`.
.. versionadded:: 1.1
"""
return hash((self.__collection, self.__id, self.__database,
tuple(sorted(self.__kwargs.items()))))
def __deepcopy__(self, memo):
"""Support function for `copy.deepcopy()`.
.. versionadded:: 1.10
"""
return DBRef(deepcopy(self.__collection, memo),
deepcopy(self.__id, memo),
deepcopy(self.__database, memo),
deepcopy(self.__kwargs, memo))