Enums

Protobuf enums map to Python IntEnum subclasses. Values compare equal to plain integers and can be used anywhere an integer is expected.

from gen.example_pb import PhoneType

user.phone_type = PhoneType.MOBILE
user.phone_type == 1   # True

Open and closed enums

In proto3 and editions, enums are open by default: unknown integer values are accepted during parsing and preserved for round-tripping. Proto2 enums are closed: unknown values are rejected during parsing.

The desc().open attribute indicates which behavior applies:

PhoneType.desc().open   # True (proto3), False (proto2/closed)

JSON representation

By default, enum values serialize to their string name in ProtoJSON:

msg.to_json()   # {"phoneType": "PHONE_TYPE_MOBILE"}

To serialize as integers instead, pass print_enums_as_ints=True:

msg.to_json(print_enums_as_ints=True)   # {"phoneType": 1}

See Serialization for the full list of JSON options.

For details on how enum value names are generated, see Enum value prefix stripping.