> Status: Experimental
`openapi-express` is a typesafe [Express](https://expressjs.com/) Router wrapper supporting [OpenAPI](https://www.openapis.org/) types.
- **Typesafe**: Build with TypeScript for strong type safety and support for [`openapi-typescript`](https://github.com/drwpow/openapi-typescript) types
- **Validation**: Ensures request validation against defined schemas using [`zod`](https://zod.dev/)
### Motivation
Provide a typesafe, straightforward, and lightweight wrapper for the [Express](https://expressjs.com/) 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.
```bash
npx openapi-typescript ./path/to/my/schema.yaml -o ./path/to/my/schema.d.ts
```
[More info](https://github.com/drwpow/openapi-typescript/tree/main/packages/openapi-typescript)
### 2. Create an OpenAPI Router
Import the generated `paths` and use `createOpenApiRouter()` to create an OpenAPI router.
`router.ts`
```ts
import { createOpenApiRouter } from 'openapi-express';
import { paths } from './openapi-paths'; // Import generated paths
export const router: Router = Router();
export const openApiRouter = createOpenApiRouter(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`
```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`
```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);
}
);
```