bson – BSON (Binary JSON) Encoding and Decoding

BSON (Binary JSON) encoding and decoding.

The mapping from Python types to BSON types is as follows:

Python Type BSON Type Supported Direction
None null both
bool boolean both
int [1] int32 / int64 py -> bson
long int64 py -> bson
bson.int64.Int64 int64 both
float number (real) both
string string py -> bson
unicode string both
list array both
dict / SON object both
datetime.datetime [2] [3] date both
bson.regex.Regex regex both
compiled re [4] regex py -> bson
bson.binary.Binary binary both
bson.objectid.ObjectId oid both
bson.dbref.DBRef dbref both
None undefined bson -> py
unicode code bson -> py
bson.code.Code code py -> bson
unicode symbol bson -> py
bytes (Python 3) [5] binary both

Note that, when using Python 2.x, to save binary data it must be wrapped as an instance of bson.binary.Binary. Otherwise it will be saved as a BSON string and retrieved as unicode. Users of Python 3.x can use the Python bytes type.

[1]A Python int will be saved as a BSON int32 or BSON int64 depending on its size. A BSON int32 will always decode to a Python int. A BSON int64 will always decode to a Int64.
[2]datetime.datetime instances will be rounded to the nearest millisecond when saved
[3]all datetime.datetime instances are treated as naive. clients should always use UTC.
[4]Regex instances and regular expression objects from re.compile() are both saved as BSON regular expressions. BSON regular expressions are decoded as Regex instances.
[5]The bytes type from Python 3.x is encoded as BSON binary with subtype 0. In Python 3.x it will be decoded back to bytes. In Python 2.x it will be decoded to an instance of Binary with subtype 0.
class bson.BSON

BSON (Binary JSON) data.

Warning

Using this class to encode and decode BSON adds a performance cost. For better performance use the module level functions encode() and decode() instead.

decode(codec_options=CodecOptions(document_class=dict, tz_aware=False, uuid_representation=UuidRepresentation.PYTHON_LEGACY, unicode_decode_error_handler='strict', tzinfo=None, type_registry=TypeRegistry(type_codecs=[], fallback_encoder=None)))

Decode this BSON data.

By default, returns a BSON document represented as a Python dict. To use a different MutableMapping class, configure a CodecOptions:

>>> import collections  # From Python standard library.
>>> import bson
>>> from bson.codec_options import CodecOptions
>>> data = bson.BSON.encode({'a': 1})
>>> decoded_doc = bson.BSON(data).decode()
<type 'dict'>
>>> options = CodecOptions(document_class=collections.OrderedDict)
>>> decoded_doc = bson.BSON(data).decode(codec_options=options)
>>> type(decoded_doc)
<class 'collections.OrderedDict'>
Parameters:

Changed in version 3.0: Removed compile_re option: PyMongo now always represents BSON regular expressions as Regex objects. Use try_compile() to attempt to convert from a BSON regular expression to a Python regular expression object.

Replaced as_class, tz_aware, and uuid_subtype options with codec_options.

Changed in version 2.7: Added compile_re option. If set to False, PyMongo represented BSON regular expressions as Regex objects instead of attempting to compile BSON regular expressions as Python native regular expressions, thus preventing errors for some incompatible patterns, see PYTHON-500.

classmethod encode(document, check_keys=False, codec_options=CodecOptions(document_class=dict, tz_aware=False, uuid_representation=UuidRepresentation.PYTHON_LEGACY, unicode_decode_error_handler='strict', tzinfo=None, type_registry=TypeRegistry(type_codecs=[], fallback_encoder=None)))

Encode a document to a new BSON instance.

A document can be any mapping type (like dict).

Raises TypeError if document is not a mapping type, or contains keys that are not instances of basestring (str in python 3). Raises InvalidDocument if document cannot be converted to BSON.

Parameters:
  • document: mapping type representing a document
  • check_keys (optional): check if keys start with ‘$’ or contain ‘.’, raising InvalidDocument in either case
  • codec_options (optional): An instance of CodecOptions.

Changed in version 3.0: Replaced uuid_subtype option with codec_options.

bson.decode(data, codec_options=CodecOptions(document_class=dict, tz_aware=False, uuid_representation=UuidRepresentation.PYTHON_LEGACY, unicode_decode_error_handler='strict', tzinfo=None, type_registry=TypeRegistry(type_codecs=[], fallback_encoder=None)))

Decode BSON to a document.

By default, returns a BSON document represented as a Python dict. To use a different MutableMapping class, configure a CodecOptions:

>>> import collections  # From Python standard library.
>>> import bson
>>> from bson.codec_options import CodecOptions
>>> data = bson.encode({'a': 1})
>>> decoded_doc = bson.decode(data)
<type 'dict'>
>>> options = CodecOptions(document_class=collections.OrderedDict)
>>> decoded_doc = bson.decode(data, codec_options=options)
>>> type(decoded_doc)
<class 'collections.OrderedDict'>
Parameters:
  • data: the BSON to decode. Any bytes-like object that implements the buffer protocol.
  • codec_options (optional): An instance of CodecOptions.

New in version 3.9.

bson.decode_all(data, codec_options=CodecOptions(document_class=dict, tz_aware=False, uuid_representation=UuidRepresentation.PYTHON_LEGACY, unicode_decode_error_handler='strict', tzinfo=None, type_registry=TypeRegistry(type_codecs=[], fallback_encoder=None)))

Decode BSON data to multiple documents.

data must be a bytes-like object implementing the buffer protocol that provides concatenated, valid, BSON-encoded documents.

Parameters:
  • data: BSON data
  • codec_options (optional): An instance of CodecOptions.

Changed in version 3.9: Supports bytes-like objects that implement the buffer protocol.

Changed in version 3.0: Removed compile_re option: PyMongo now always represents BSON regular expressions as Regex objects. Use try_compile() to attempt to convert from a BSON regular expression to a Python regular expression object.

Replaced as_class, tz_aware, and uuid_subtype options with codec_options.

Changed in version 2.7: Added compile_re option. If set to False, PyMongo represented BSON regular expressions as Regex objects instead of attempting to compile BSON regular expressions as Python native regular expressions, thus preventing errors for some incompatible patterns, see PYTHON-500.

bson.decode_file_iter(file_obj, codec_options=CodecOptions(document_class=dict, tz_aware=False, uuid_representation=UuidRepresentation.PYTHON_LEGACY, unicode_decode_error_handler='strict', tzinfo=None, type_registry=TypeRegistry(type_codecs=[], fallback_encoder=None)))

Decode bson data from a file to multiple documents as a generator.

Works similarly to the decode_all function, but reads from the file object in chunks and parses bson in chunks, yielding one document at a time.

Parameters:
  • file_obj: A file object containing BSON data.
  • codec_options (optional): An instance of CodecOptions.

Changed in version 3.0: Replaced as_class, tz_aware, and uuid_subtype options with codec_options.

New in version 2.8.

bson.decode_iter(data, codec_options=CodecOptions(document_class=dict, tz_aware=False, uuid_representation=UuidRepresentation.PYTHON_LEGACY, unicode_decode_error_handler='strict', tzinfo=None, type_registry=TypeRegistry(type_codecs=[], fallback_encoder=None)))

Decode BSON data to multiple documents as a generator.

Works similarly to the decode_all function, but yields one document at a time.

data must be a string of concatenated, valid, BSON-encoded documents.

Parameters:
  • data: BSON data
  • codec_options (optional): An instance of CodecOptions.

Changed in version 3.0: Replaced as_class, tz_aware, and uuid_subtype options with codec_options.

New in version 2.8.

bson.encode(document, check_keys=False, codec_options=CodecOptions(document_class=dict, tz_aware=False, uuid_representation=UuidRepresentation.PYTHON_LEGACY, unicode_decode_error_handler='strict', tzinfo=None, type_registry=TypeRegistry(type_codecs=[], fallback_encoder=None)))

Encode a document to BSON.

A document can be any mapping type (like dict).

Raises TypeError if document is not a mapping type, or contains keys that are not instances of basestring (str in python 3). Raises InvalidDocument if document cannot be converted to BSON.

Parameters:
  • document: mapping type representing a document
  • check_keys (optional): check if keys start with ‘$’ or contain ‘.’, raising InvalidDocument in either case
  • codec_options (optional): An instance of CodecOptions.

New in version 3.9.

bson.gen_list_name()

Generate “keys” for encoded lists in the sequence b”0”, b”1”, b”2”, …

The first 1000 keys are returned from a pre-built cache. All subsequent keys are generated on the fly.

bson.has_c()

Is the C extension installed?

bson.is_valid(bson)

Check that the given string represents valid BSON data.

Raises TypeError if bson is not an instance of str (bytes in python 3). Returns True if bson is valid BSON, False otherwise.

Parameters:
  • bson: the data to be validated

Sub-modules: