Unable to do anything with response Any protos in REST client

[melissachang]

In Go REST Apiary libraries, response Any proto is map[string]interface{}. I can't figure out how to convert this to any other type:

• byte[]
• Any proto
• Original proto that Any proto represents

Ross requested me to mention some people: @bradfitz @jba @zombiezen

[zombiezen]

The concrete proposal I had was that instead of having these fields generate an interface{} type, they should store a json.RawMessage. Then the user of the client could pick which message it should be and it becomes regular JSON semantics.

This would be a breaking API change, but I would argue that map[string]interface{} is unhelpful enough that it's worth it. FWIW, the current generator renamed the actual OperationMetadata struct to OperationMetadata1 to avoid conflicts with the type OperationMetadata interface{}.

[zombiezen]

So in testing this out in the real world, my fix has a correctness issue due to golang/go#14493: json.RawMessage fields get encoded as base64. While the correct behavior will land in Go 1.8, we have too many targets (namely App Engine) that aren't updated to 1.8. As I see it, there are two options:

1. Roll back b679263.
2. Roll forward and use *json.RawMessage.

@jba, thoughts?

[zombiezen]

@jba suggested an even better solution: creating a googleapi.RawMessage type that has the correct behavior, independent of Go version.

[dsnet]

Copying the implementation of json.RawMessage sounds like a good way to get around this problem. I think using *json.RawMessage is really dirty.

It would be nice to be able to alias googleapi.RawMessage as json.RawMessage in the not-so-distant future.

[zombiezen]

Yup, https://code-review.googlesource.com/9811 out for review does exactly this.