# Copyright 2015 MongoDB, 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 working with read concerns.""" from bson.py3compat import string_type class ReadConcern(object): """ReadConcern :Parameters: - `level`: (string) The read concern level specifies the level of isolation for read operations. For example, a read operation using a read concern level of ``majority`` will only return data that has been written to a majority of nodes. If the level is left unspecified, the server default will be used. .. versionadded:: 3.2 """ def __init__(self, level=None): if level is None or isinstance(level, string_type): self.__level = level else: raise TypeError( 'level must be a string or None.') @property def level(self): """The read concern level.""" return self.__level @property def ok_for_legacy(self): """Return ``True`` if this read concern is compatible with old wire protocol versions.""" return self.level is None or self.level == 'local' @property def document(self): """The document representation of this read concern. .. note:: :class:`ReadConcern` is immutable. Mutating the value of :attr:`document` does not mutate this :class:`ReadConcern`. """ doc = {} if self.__level: doc['level'] = self.level return doc def __eq__(self, other): if isinstance(other, ReadConcern): return self.document == other.document return NotImplemented def __repr__(self): if self.level: return 'ReadConcern(%s)' % self.level return 'ReadConcern()' DEFAULT_READ_CONCERN = ReadConcern()