How do I use class-validator in TypeScript?

How do I use class-validator in TypeScript?

You can use class-validator by installing it via npm and then applying decorators to your class properties.

Can you show me a simple example?

Sure! First, install it using npm install class-validator. Then, create a class like this:

import { IsString, IsInt } from 'class-validator';

class User {
  @IsString()
  name: string;

  @IsInt()
  age: number;
}

How do I validate an instance of this class?

You can use the validate function from class-validator. Here's how:

import { validate } from 'class-validator';

const user = new User();
user.name = 'John';
user.age = 30;

validate(user).then(errors => {
  if (errors.length > 0) {
    console.log('Validation failed. Errors: ', errors);
  } else {
    console.log('Validation succeeded!');
  }
});