How to use express-validator with koa framework?

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by lottie , in category: Javascript , 8 months ago

How to use express-validator with koa framework?

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1 answer

by darrion.kuhn , 5 months ago

@lottie 

To use the express-validator library with the Koa framework, you can create a middleware function that integrates the validation functionality. Here is an example implementation:

  1. Install the required packages:
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npm install koa koa-router express-validator


  1. Create a Koa application and define a route with validation:
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const Koa = require('koa');
const Router = require('koa-router');
const { body, validationResult } = require('express-validator');

const app = new Koa();
const router = new Router();

// Define a route with validation
router.post('/api/user', [
  body('username').isLength({ min: 5 }).withMessage('Username must be at least 5 characters'),
  body('email').isEmail().withMessage('Invalid email address'),
], async (ctx) => {
  const errors = validationResult(ctx);
  
  if (!errors.isEmpty()) {
    ctx.status = 400;
    ctx.body = { errors: errors.array() };
  } else {
    // Process the request
    // ...
  }
});

app.use(router.routes());
app.listen(3000, () => {
  console.log('Server is running on http://localhost:3000');
});


In this example, we create a Koa application and define a route /api/user that expects a POST request. We use the body function from express-validator to define validation rules for the username and email fields. If there are validation errors, we return a 400 Bad Request response with the error messages. Otherwise, we process the request as usual.

  1. Test the route using a tool like Postman or curl:
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curl -X POST http://localhost:3000/api/user -d "username=test&[email protected]"


This is a basic example of how you can integrate express-validator with the Koa framework to validate request data. You can customize the validation rules and error handling based on your requirements.