Status: Experimental

openapi-express is a typesafe Express Router wrapper supporting OpenAPI types.

• Typesafe: Build with TypeScript for strong type safety and support for openapi-typescript types
• Validation: Ensures request validation against defined schemas using zod

Motivation

Provide a typesafe, straightforward, and lightweight wrapper for the Express Router that seamlessly integrates with OpenAPI schemas using openapi-typescript. It aims to simplify error handling and request validation.

📖 Usage

1. Generate TypeScript Definitions

Use openapi-typescript to generate TypeScript definitions from your OpenAPI schema.

npx openapi-typescript ./path/to/my/schema.yaml -o ./path/to/my/schema.d.ts

More info

2. Create an OpenAPI Router

Import the generated paths and use createOpenApiRouter() to create an OpenAPI router.

router.ts

import { createOpenApiRouter } from 'openapi-express';
import { paths } from './openapi-paths'; // Import generated paths

export const router: Router = Router();
export const openApiRouter = createOpenApiRouter<paths>(router);

3. Use the Router in an Express App

Integrate the OpenAPI router into your Express application to handle requests. Use express.json() middleware to parse incoming JSON requests.

app.ts

import express from 'express';
import { router } from './router';

const app = express();

app.use(express.json()); // For parsing application/json

app.use('/', router);

4. Define the Endpoints with Full Type Safety

Define your API endpoints with full type safety and request validation using Zod. TypeScript provides type safety at compile time, but runtime validation is necessary to ensure incoming requests meet the expected structure and types. Zod helps with this by providing a schema-based validation mechanism. If a schema is invalid, a ValidationError is thrown.

routes/posts.ts

import { Router } from 'express';
import { z } from 'zod';
import { openApiRouter } from '../router';

const posts = [
    { id: '1', title: 'First Post', content: 'This is the first post.' },
    { id: '2', title: 'Second Post', content: 'This is the second post.' }
];

// Get all posts
openApiRouter.get(
    '/posts',
    {},
    async (req, res) => {
        res.json(posts);
    }
);

// Get a post by ID
openApiRouter.get(
    '/posts/{id}',
    {
        pathSchema: {
            id: z.string()
        }
    },
    async (req, res) => {
        const post = posts.find(p => p.id === req.params.id);
        if (post) {
            res.json(post);
        } else {
            res.status(404).json({ message: 'Post not found' });
        }
    }
);

// Create a new post
openApiRouter.post(
    '/posts',
    {
        bodySchema: z.object({
            title: z.string(),
            content: z.string()
        })
    },
    async (req, res) => {
        const newPost = {
            id: (posts.length + 1).toString(),
            ...req.body
        };
        posts.push(newPost);
        res.status(201).json(newPost);
    }
);