How to use a prototbuf map in Python?

Question

Given a proto definition

message EndpointResult {
    int32 endpoint_id = 1;
    // property id as key
    map<int32, TimeSeries> properties = 2;
}

message TimeSeries {
    repeated TimeEntry value = 2;
}

message TimeEntry {
    int32 time_unit = 1;
    float value = 2;
}

I wish to populate the map in the EndpointResult class. I have tried different approaches suggested in the docs but all raise a error for me.

Setting up a test class

end_point_rslt = nom.EndpointResult()
end_point_rslt.endpoint_id=0

ts = nom.TimeSeries()
te = ts.value.add()
te.time_unit = 0
te.value = 5.

Then trying the different approaches:

end_point_rslt.properties[0] = ts

ValueError: Direct assignment of submessage not allowed

end_point_rslt.properties[0].submessage_field = ts

AttributeError: Assignment not allowed (no field "submessage_field" in protocol message object).

end_point_rslt.properties.get_or_create(0)
end_point_rslt.properties[0] = ts

ValueError: Direct assignment of submessage not allowed

end_point_rslt.properties.get_or_create(0)
end_point_rslt.properties[0].submessage_field = ts

AttributeError: Assignment not allowed (no field "submessage_field" in protocol message object).

end_point_rslt.properties = {0 : ts}

AttributeError: Assignment not allowed to repeated field "properties" in protocol message object.

end_point_rslt.properties.get_or_create(0)
end_point_rslt.properties = {0 : ts}

TypeError: Can't set composite field

Any example of how to use a protocol buffer map in python would be greatly appreciate!

Answer 1

After staring at the docs, I realized that the problem was me assigning a class to the dictionary.

The correct syntax is

end_point_rslt = nom.EndpointResult()
end_point_rslt.endpoint_id=0
te = end_point_rslt.properties[0].value.add()
te.time_unit = 0
te.value = 5.