如何使用protobuf在python中设置oneof字段值

Question

I have a protobuf with oneof field. Does "Oneof" take one of the field values or all together? Not sure if there is a way to set this.

I am expecting a true value when I run "pb2.HasField('signal')

Proto file:

message Log {
  string id = 1;       
  Severity severity = 2; 
  string Uid = 3;        
oneof signal{
    GPS gps_log = 1;
    Ignition ignition_log = 2;
  }
enum Severity {
    info = 0;
    critical = 1
}
message GPS{
  EventType event_type = 1;
enum EventType {
    ON = 0;
    OFF = 1;
  }
}

message Ignition{
  EventType event_type = 1;
enum EventType {
    ON = 0;
    OFF = 1;
  }
}

So after importing pb2 in python, how do I set value for the 'signal'. When I try :

message=pb2.Log()
res = message.DESCRIPTOR.fields
res = [field.name for field in message.DESCRIPTOR.fields]
The o/p is ['id','severity','Uid','gps_log','ignition']  - All the fields.

How to force the 'Oneof' field to have only on of the messages, eg GPS. Also pb2.WhichOneof('signal') returns nothing (empty). I am not even sure, if this is something possible.

Answer 1

Looks like i was missing the master protobuf file,which the information I wanted. The field values are specified in the prot_master file.