express-validator setup - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is express-validator used for in an Express app?

express-validator helps check and validate user input in Express apps to keep data clean and safe.

beginner

How do you install express-validator in your project?

Run npm install express-validator in your project folder to add it.

beginner

Which function from express-validator do you use to define validation rules?

You use check() or body() to set rules for request data fields.

intermediate

What does validationResult(req) do in your route handler?

It collects the results of validations and tells you if there are errors in the user input.

intermediate

Show a simple example of setting up express-validator in an Express POST route.

<pre>import { check, validationResult } from 'express-validator';

app.post('/signup', [
  check('email').isEmail(),
  check('password').isLength({ min: 6 })
], (req, res) => {
  const errors = validationResult(req);
  if (!errors.isEmpty()) {
    return res.status(400).json({ errors: errors.array() });
  }
  res.send('Signup successful');
});</pre>

What command installs express-validator?

A npm install express

B npm install express-validator

C npm install validator

D npm install express-validator-cli

The correct package is express-validator, installed with npm install express-validator.

Which function is used to check a field in express-validator?

A check()

B verify()

C validate()

D inspect()

check() is used to define validation rules for request fields.

What does validationResult(req) return?

A The original request object

B A boolean true if valid

C An array of validation errors

D The response object

It returns an object containing any validation errors found in the request.

Where do you place validation middleware in an Express route?

A In the app.listen callback

B After the route handler

C Inside the route handler only

D Before the route handler

Validation middleware runs before the route handler to check input first.

Which of these is a valid validation rule with express-validator?

A check('email').isEmail()

B check('name').isBoolean()

C check('password').isNumber()

D check('age').isEmail()

check('email').isEmail() correctly checks if the email field is a valid email.

Explain how to set up express-validator in an Express POST route to validate user input.

Think about middleware placement and error checking.

Describe the role of validationResult in the validation process with express-validator.

It helps decide if input is good or not.