Can I use response_format and functions together in the API call?

API
1

I am working on a Q&A application where I want to generate structured responses from the OpenAI API in a specified JSON format. In some cases, I also need to generate images to accompany the response when required (e.g., to visually explain a concept). To achieve this, I’ve implemented both function calling (to generate images) and a custom response format. However, I encounter a 400 Client Error: Bad Request when making the API call to:

https://api.openai.com/v1/chat/completions

Is it possible to use both response_format and functions simultaneously, or is there an issue in my approach? Below is the relevant code I am using:

def get_function_definitions():
    """Define available functions for the model."""
    return [{
        "name": "generate_image",
        "description": "Generate an image based on the given description",
        "parameters": {
            "type": "object",
            "properties": {
                "description": {
                    "type": "string",
                    "description": "A detailed description of the image"
                }
            },
            "required": ["description"]
        }
    }]

def get_response_format():
    """Define the expected response format."""
    return {
        "type": "json_schema",
        "schema": {
            "type": "object",
            "properties": {
                "topic": {"type": "string"},
                "questions": {
                    "type": "array",
                    "items": {
                        "type": "object",
                        "properties": {
                            "question_number": {"type": "integer"},
                            "question": {"type": "string"},
                            "answer": {"type": "string"},
                            "image_url": {"type": "string", "optional": True}
                        },
                        "required": ["question_number", "question", "answer"]
                    }
                },
                "summary": {"type": "string"}
            },
            "required": ["topic", "questions", "summary"]
        }
    }

def make_api_call(system_prompt, user_prompt, messages=None):
    """Make API call with both function calling and response format."""
    if messages is None:
        messages = [
            {"role": "system", "content": system_prompt},
            {"role": "user", "content": user_prompt}
        ]

    request_data = {
        "model": "gpt-4o",
        "messages": messages,
        "functions": get_function_definitions(),
        "function_call": "auto",
        "response_format": get_response_format(),  # Combining functions & response format
        "temperature": 0.3
    }

    try:
        response = requests.post(
            url="https://api.openai.com/v1/chat/completions",
            headers={
                "Authorization": f"Bearer {OPENAI_API_KEY}",
                "Content-Type": "application/json"
            },
            json=request_data
        )
        response.raise_for_status()
        return response.json()
    except requests.exceptions.RequestException as e:
        print(f"Error making API call: {str(e)}")

def main():
    system_prompt = """You are an educational assistant. Provide responses in the
    specified JSON format. When explaining complex concepts, generate images only 
    if necessary through the provided function."""
    
    user_prompt = "Explain OOP concepts. Include at least one question that would benefit from a visual explanation."

    response = make_api_call(system_prompt, user_prompt)
    if "error" not in response:
        print("\nFormatted Response:")
        print(json.dumps(response, indent=2))
    else:
        print(f"\nError occurred: {response['error']}")
        
if __name__ == "__main__":
    main()