json: cannot unmarshal object into Go struct field ChatCompletionResponseFormatJSONSchema.response_format.json_schema.schema of type json.Marshaler

[nodelrd]

json: cannot unmarshal object into Go struct field ChatCompletionResponseFormatJSONSchema.response_format.json_schema.schema of type json.Marshaler

github.com/sashabaranov/go-openai v1.32.3

[lei-lei-shanda]

I can confirm the bug. this is a minimal working example, taken from openai example:

package main

import (
	"encoding/json"

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

const request = `
{
    "model": "gpt-4o-2024-08-06",
    "stream": true,
    "messages": [
      {
        "role": "system",
        "content": "You are a helpful math tutor. Guide the user through the solution step by step."
      },
      {
        "role": "user",
        "content": "how can I solve 8x + 7 = -23"
      }
    ],
    "response_format": {
      "type": "json_schema",
      "json_schema": {
        "name": "math_reasoning",
        "schema": {
          "type": "object",
          "properties": {
            "steps": {
              "type": "array",
              "items": {
                "type": "object",
                "properties": {
                  "explanation": { "type": "string" },
                  "output": { "type": "string" }
                },
                "required": ["explanation", "output"],
                "additionalProperties": false
              }
            },
            "final_answer": { "type": "string" }
          },
          "required": ["steps", "final_answer"],
          "additionalProperties": false
        },
        "strict": true
      }
    }
  }
`

func main() {
	ccr := &goopenai.ChatCompletionRequest{}
	err := json.Unmarshal([]byte(request), ccr)
	if err != nil {
		panic(err)
	}
}

the issue here is that json.Marshaler is an interface. It would be better if this is jsonschema.Definition or json.RawMessage.

[lei-lei-shanda]

this is the offending MR I think.

a3bd256#diff-c2ade2f386c41794d5ebc57ee49b57a5fca8082e03255e5bff13977cbc061287

[lukeocodes]

I can also reproduce this @sashabaranov

	var req openai.ChatCompletionRequest

	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		log.Warn().Err(err).Msg("malformed JSON request")
		return
	}

Request body is the very same example above, the helpful math tutor

[lukeocodes]

A temporary workaround:

	// Handle response format conversion if present
	if req.ResponseFormat != nil {
		openaiReq.ResponseFormat = &openai.ChatCompletionResponseFormat{
			Type: openai.ChatCompletionResponseFormatType(req.ResponseFormat.Type),
		}
		if req.ResponseFormat.JSONSchema != nil {
			openaiReq.ResponseFormat.JSONSchema = &openai.ChatCompletionResponseFormatJSONSchema{
				Name:        req.ResponseFormat.JSONSchema.Name,
				Description: req.ResponseFormat.JSONSchema.Description,
				Schema:      req.ResponseFormat.JSONSchema.Schema,
				Strict:      req.ResponseFormat.JSONSchema.Strict,
			}
		}
	}

[alejandrojnm]

Is there any update on this?

[alejandrojnm]

I found if you pass the the object manually like JSON schema work , but if you use a Zod (from typescript) don't work, the object is parsed but when you send that to a custom endpoint (llama 3) don't work, llama respond with this error, status code: 500, status: 500 Internal Server Error, message: invalid character 'I' looking for beginning of value, body: Internal Server Error