function-schema 0.2.0

A small utility to generate JSON schemas for python functions.

Function schema

This is a small utility to generate JSON schemas for python functions. With power of type annotations, it is possible to generate a schema for a function without describing it twice.

At this moment, extracting schema from a function is only useful for OpenAI API function-call feature. But it can be used for other purposes for example to generate documentation in the future.

Installation

pip install function-schema

Usage

from typing import Annotated, Optional
import enum

def get_weather(
    city: Annotated[str, "The city to get the weather for"],
    unit: Annotated[
        Optional[str],
        "The unit to return the temperature in",
        enum.Enum("Unit", "celcius fahrenheit")
    ] = "celcius",
) -> str:
    """Returns the weather for the given city."""
    return f"Weather for {city} is 20°C"

Function description is taken from the docstring. Type hinting with typing.Annotated for annotate additional information about the parameters and return type.

• type can be typing.Union, typing.Optional. (T | None for python 3.10+)
• string value of Annotated is used as a description
• enum value of Annotated is used as an enum schema

import json
from function_schema import get_function_schema

schema = get_function_schema(get_weather)
print(json.dumps(schema, indent=2))

Will output:

{
  "name": "get_weather",
  "description": "Returns the weather for the given city.",
  "parameters": {
    "type": "object",
    "properties": {
      "city": {
        "type": "string",
        "description": "The city to get the weather for"
      },
      "unit": {
        "type": "string",
        "description": "The unit to return the temperature in",
        "enum": [
          "celcius",
          "fahrenheit"
        ],
        "default": "celcius"
      }
    },
  }
  "required": [
    "city"
  ]
}

You can use this schema to make a function call in OpenAI API:

import openai
openai.api_key = "sk-..."

result = openai.ChatCompletion.create(
    model="gpt-3.5-turbo",
    messages=[
      {"role": "user", "content": "What's the weather like in Seoul?"}
    ],
    functions=[
        get_function_schema(get_weather)
    ],
    function_call="auto",
)

CLI usage

function_schema mymodule.py my_function

License

MIT License