Function Calling Practical Guide

import openai
import json

# Define function
def get_weather(location: str, unit: str = "celsius"):
    """Get weather for specified location"""
    # Simulate weather API call
    return json.dumps({
        "location": location,
        "temperature": 22,
        "unit": unit,
        "forecast": "sunny"
    })

# Define function specification
functions = [
    {
        "name": "get_weather",
        "description": "Get current weather for specified location",
        "parameters": {
            "type": "object",
            "properties": {
                "location": {
                    "type": "string",
                    "description": "City name, for example: Beijing, Shanghai"
                },
                "unit": {
                    "type": "string",
                    "enum": ["celsius", "fahrenheit"],
                    "description": "Temperature unit"
                }
            },
            "required": ["location"]
        }
    }
]

# Send request
response = openai.ChatCompletion.create(
    model="gpt-4o",
    messages=[
        {"role": "user", "content": "What's the weather like in Beijing today? "}
    ],
    functions=functions,
    function_call="auto"  # Automatically decide whether to call function
)

# Handle response
if response.choices[0].message.get("function_call"):
    function_name = response.choices[0].message["function_call"]["name"]
    function_args = json.loads(response.choices[0].message["function_call"]["arguments"])
    
    # Call actual function
    if function_name == "get_weather":
        result = get_weather(**function_args)
        
        # Send function result back to model
        second_response = openai.ChatCompletion.create(
            model="gpt-4o",
            messages=[
                {"role": "user", "content": "What's the weather like in Beijing today? "},
                response.choices[0].message,
                {
                    "role": "function",
                    "name": function_name,
                    "content": result
                }
            ]
        )
        
        print(second_response.choices[0].message.content)