Support unmarshaling request structs

[mattmueller-stripe]

Hey OpenAI team!

We're working on an OpenAI API-compatible proxy. Roughly:

user -> proxy -> openai api

To ease the maintainance burden, we'd like to import the request and response structs from this library into our proxy, specifically structs like:

type ChatCompletionNewParams struct {
	// A list of messages comprising the conversation so far. Depending on the
	// [model](https://platform.openai.com/docs/models) you use, different message
	// types (modalities) are supported, like
	// [text](https://platform.openai.com/docs/guides/text-generation),
	// [images](https://platform.openai.com/docs/guides/vision), and
	// [audio](https://platform.openai.com/docs/guides/audio).
	Messages param.Field[[]ChatCompletionMessageParamUnion] `json:"messages,required"`
	// ID of the model to use. See the
	// [model endpoint compatibility](https://platform.openai.com/docs/models#model-endpoint-compatibility)
	// table for details on which models work with the Chat API.
	Model param.Field[ChatModel] `json:"model,required"`
	// ...
}

(code).

This is possible today, however when we try to unmarshal the request into those structs, we get the following error:

json: cannot unmarshal string into Go struct field ChatCompletionNewParams.model of type param.Field[string]

I believe this is because param.Field doesn't implement a json.Unmarshaler.

Would it be possible to support unmarshaling on all the request structs:

var chatRequest openai.ChatCompletionNewParams
_ := json.Unmarshal(body, &chatRequest)

We'd also need marshaling on all the response structs, but I believe that's supported already!

[jacobzim-stl]

We're very keen to release support for this, but it will require lots of testing since things get tricky with nested unions etc.

The new V2 was designed with support for this in mind, but it will probably not accompany the initial release. We're aiming to support it by next week.

[devonhk]

@jacobzim-stl

The new V2 was designed with support for this in mind, but it will probably not accompany the initial release. We're aiming to support it by next week.

Just so I understand, by initial release are you referring to v1 (since the latest release is still in beta v0.1.0-beta.9)?

If so, any ideas on what the timeline is for the v2 release (are we talking about months?) .

[gluonfield]

Very important feature request, any ETA on it?

[jacobzim-stl]

I'm hoping to get a preliminary implementation out today.

[varungup90]

@jacobzim-stl I am using release .beta10. Unmarshal for model works but messages is returning null.

Sample Code

chatObj := openai.ChatCompletionNewParams{
		Messages: []openai.ChatCompletionMessageParamUnion{{
			OfUser: &openai.ChatCompletionUserMessageParam{
				Content: openai.ChatCompletionUserMessageParamContentUnion{
					OfString: openai.String("Say this is a test"),
				},
			},
		}},
		Model: shared.ChatModelO3Mini,
	}
	input, err := chatObj.MarshalJSON()
	if err != nil {
		klog.Error(err)
	}
	klog.Info(string(input))

	chatCompletionObj := openai.ChatCompletionNewParams{}
	err = json.Unmarshal(input, &chatCompletionObj)
	if err != nil {
		klog.ErrorS(err, "unable to process chat completion request")
	}
	klog.InfoS("debug", "model", chatCompletionObj.Model, "messages", chatCompletionObj.Messages)

Output

I0430 16:41:06.217860   65860 types_test.go:50] {"messages":[{"content":"Say this is a test","role":"user"}],"model":"o3-mini"}
I0430 16:41:06.218349   65860 types_test.go:57] "debug" model="o3-mini" messages=[null]

[gluonfield]

Just checked, messages Unmarshal to null

package main

import (
	"encoding/json"
	"fmt"

	"github.com/openai/openai-go"
)

func main() {
	messages := []openai.ChatCompletionMessageParamUnion{
		openai.SystemMessage("one"),
		openai.UserMessage("two"),
	}

	input, err := json.Marshal(messages)
	if err != nil {
		panic(err)
	}

	var unmarshalledMessages []openai.ChatCompletionMessageParamUnion

	err = json.Unmarshal(input, &unmarshalledMessages)
	if err != nil {
		panic(err)
	}
	fmt.Println(unmarshalledMessages)
}

Returns

 go run ./main.go
[{<nil> <nil> <nil> <nil> <nil> <nil> {{<nil>}}} {<nil> <nil> <nil> <nil> <nil> <nil> {{<nil>}}}]

Any ideas @jacobzim-stl

[varungup90]

Below are few issues I came across for unmarshal with latest release v0.1.0-beta.10

• ChatCompletionsNewParams: unmarshal for messages does not work
• ChatCompletionsNewParams: no stream field is present (only stream options is available). We are building a proxy layer and would want to identify if the incoming request has stream enabled.
• CompletionsNewParams: unmarshal for Prompt does not work.

[wangxj03]

Any updates on this? 🙏

[jacobzim-stl]

This should now be supported. Thanks for your patience.

[wangxj03]

can we release 0.1.0-beta.11? it hasn't showed up in https://github.com/openai/openai-go/releases

[relyt0925]

@varungup90 did you fix the stream piece? I still don't see it in main:
https://github.com/openai/openai-[go/pull/549](https://www.golinks.io/pull/549?trackSource=github)