Message with message nested in map cannot be created with dict

[dizcology]

Generate the python GAPIC library with the following proto:

// in googleapis/google/cloud/mypackge/v1/some.proto
syntax = "proto3";

package google.cloud.mypackage;

message Outer {
    AMap inner = 1;
}

message AMap {
    map<string, Stuff> some_mapping = 1;
}

message Stuff {}

The resulting library cannot be used to create certain Outer messages:

(1)

mypackage.Outer(inner={'some_mapping': {'a': {}}})

raises TypeError: Parameter to MergeFrom() must be instance of same class: expected google.cloud.mypackage.Stuff got dict..

(2)

mypackage.Outer(inner={'some_mapping': {'a': mypackage.Stuff()}})

raises TypeError: Parameter to MergeFrom() must be instance of same class: expected google.cloud.mypackage.Stuff got Stuff..

(3)

mypackage.Outer(inner=mypackage.AMap(some_mapping={'a': mypackage.Stuff()}))

works fine, and builds:

inner {
  some_mapping {
    key: "a"
    value {
    }
  }
}

[software-dov]

Minimal reproducing type:

class Boat(proto.Message): 
    class Net(proto.Message): 
        class Mollusc(proto.Message):                                                                                                                                                                                                   
            mass_kg = proto.Field(proto.INT32, number=1) 

        molluscs = proto.MapField(proto.STRING, Mollusc, number=1) 
          
    net = proto.Field(Net, number=1)

b = Boat(net={"molluscs": {"squid": {"mass_kg": 100}}})    # raises an exception

Workaround is to explicitly use types, e.g.

b = Boat(net=Boat.Net(molluscs={"squid": Boat.Net.Mollusc(mass_kg=20)}))

[busunkim96]

@software-dov Do you have a sense of how easy/hard it would be to fix this? It seems natural for folks to mix mix dict/type instantiation (especially when the request object is big).