validation-p2-index.ts

import { Router, Response, Request } from "express";
import express from "express";
import bodyParser from "body-parser";
import { validate, Matches, IsDefined } from "class-validator";
import { plainToClass, Expose } from "class-transformer";

class UserDto {
    @IsDefined()
    @Expose()
    username: String;
    @IsDefined()
    @Expose()
    @Matches(RegExp(/^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])[0-9a-zA-Z]{8,}$/))
    password: String;
    @IsDefined()
    @Expose()
    @Matches(RegExp(/^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/))
    email: String;
}

const app = express();
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
const router = Router();

router.post("/user/submit", async (req: Request, res: Response) => {
    const user = plainToClass(UserDto, req.body);
    validate(user, { skipMissingProperties: true }).then(errors => {
        // errors is an array of validation errors
        if (errors.length > 0) {
            let errorTexts = Array();
            for (const errorItem of errors) {
                errorTexts = errorTexts.concat(errorItem.constraints);
            }
            res.status(400).send(errorTexts);
            return;
        } else {
            // pass 'user' object to repository/service 
            res.json(user);
        }
    });
});
app.use(router);
app.listen(3000, () => {
    console.log('Server is running in http://localhost:3000');
});