pydantic-to-typescript

A simple CLI tool for converting pydantic models into typescript interfaces. Useful for any scenario in which python and javascript applications are interacting, since it allows you to have a single source of truth for type definitions.

This tool requires that you have the lovely json2ts CLI utility installed. Instructions can be found here: https://www.npmjs.com/package/json-schema-to-typescript

Installation

$ pip install pydantic-to-typescript

CLI

Usage

Define your pydantic models (ex: /backend/api.py):

from fastapi import FastAPI
from pydantic import BaseModel
from typing import List, Optional

api = FastAPI()

class LoginCredentials(BaseModel):
    username: str
    password: str

class Profile(BaseModel):
    username: str
    age: Optional[int]
    hobbies: List[str]

class LoginResponseData(BaseModel):
    token: str
    profile: Profile

@api.post('/login/', response_model=LoginResponseData)
def login(body: LoginCredentials):
    profile = Profile(**body.dict(), age=72, hobbies=['cats'])
    return LoginResponseData(token='very-secure', profile=profile)

Execute the command for converting these models into typescript definitions, via:

$ pydantic2ts --module backend.api --output ./frontend/apiTypes.ts

or:

$ pydantic2ts --module ./backend/api.py --output ./frontend/apiTypes.ts

or:

from pydantic2ts import generate_typescript_defs

generate_typescript_defs("backend.api", "./frontend/apiTypes.ts")

The models are now defined in typescript...

/* tslint:disable */
/**
/* This file was automatically generated from pydantic models by running pydantic2ts.
/* Do not modify it by hand - just update the pydantic models and then re-run the script
*/

export interface LoginCredentials {
  username: string;
  password: string;
}
export interface LoginResponseData {
  token: string;
  profile: Profile;
}
export interface Profile {
  username: string;
  age?: number;
  hobbies: string[];
}

...and can be used in your typescript code with complete confidence.

import { LoginCredentials, LoginResponseData } from "./apiTypes.ts";

async function login(
  credentials: LoginCredentials,
  resolve: (data: LoginResponseData) => void,
  reject: (error: string) => void
) {
  try {
    const response: Response = await fetch("/login/", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify(credentials),
    });
    const data: LoginResponseData = await response.json();
    resolve(data);
  } catch (error) {
    reject(error.message);
  }
}