codec_options – Tools for specifying BSON codec options

Tools for specifying BSON codec options.

class bson.codec_options.CodecOptions

Encapsulates options used encoding and / or decoding BSON.

The document_class option is used to define a custom type for use decoding BSON documents. Access to the underlying raw BSON bytes for a document is available using the RawBSONDocument type:

>>> from bson.raw_bson import RawBSONDocument
>>> from bson.codec_options import CodecOptions
>>> codec_options = CodecOptions(document_class=RawBSONDocument)
>>> coll = db.get_collection('test', codec_options=codec_options)
>>> doc = coll.find_one()
>>> doc.raw

The document class can be any type that inherits from MutableMapping:

>>> class AttributeDict(dict):
...     # A dict that supports attribute access.
...     def __getattr__(self, key):
...         return self[key]
...     def __setattr__(self, key, value):
...         self[key] = value
>>> codec_options = CodecOptions(document_class=AttributeDict)
>>> coll = db.get_collection('test', codec_options=codec_options)
>>> doc = coll.find_one()
>>> doc._id

See Datetimes and Timezones for examples using the tz_aware and tzinfo options.

See UUIDLegacy for examples using the uuid_representation option.

  • document_class: BSON documents returned in queries will be decoded to an instance of this class. Must be a subclass of MutableMapping. Defaults to dict.
  • tz_aware: If True, BSON datetimes will be decoded to timezone aware instances of datetime. Otherwise they will be naive. Defaults to False.
  • uuid_representation: The BSON representation to use when encoding and decoding instances of UUID. Defaults to PYTHON_LEGACY.
  • unicode_decode_error_handler: The error handler to apply when a Unicode-related error occurs during BSON decoding that would otherwise raise UnicodeDecodeError. Valid options include ‘strict’, ‘replace’, and ‘ignore’. Defaults to ‘strict’.
  • tzinfo: A tzinfo subclass that specifies the timezone to/from which datetime objects should be encoded/decoded.


Care must be taken when changing unicode_decode_error_handler from its default value (‘strict’). The ‘replace’ and ‘ignore’ modes should not be used when documents retrieved from the server will be modified in the client application and stored back to the server.


Make a copy of this CodecOptions, overriding some options:

>>> from bson.codec_options import DEFAULT_CODEC_OPTIONS
>>> options = DEFAULT_CODEC_OPTIONS.with_options(tz_aware=True)
>>> options.tz_aware

New in version 3.5.