Reading value from proto struct via protoreflect for optional fields about protobuf HOT 4 CLOSED

protoreflect.Message.Get behaves mostly equivalently to accessor methods, which return the default value for unpopulated scalar fields. For example, in your case foo.GetField() returns "" if the field field is unset.

You can test to see if a field is set with foo.ProtoReflect().Has(paramField).

The protoreflect package operates on the protobuf data model, not the Go data model, so it doesn't have a concept of a field being nil. (For example, in generated messages, the representation of an unset optional string field is (*string)(nil), but a dynamicpb.Message uses a different representation. protoreflect can work with either.)

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The internal implementation of protoreflect.Value may need to consider things like a value being nil as it is sort of the “glue” between the protobuf data model, and the Go data model. But it only surfaces strictly the protobuf data model, and the internal Go data model is strictly an obscured implementation detail.

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Thanks for explanation. So my line of code getting to know isNil is basically correct, right?

For me, the curious thing is that protoreflect.Value inside works with nilType but basically, this can never happen, right?

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Thank you for clarification. I'm closing this topic now.

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