Express Validator

Lightweight & powerful express validator designed for Typescript.

Install

$ npm i @taraj/express-validator

Basic usage

Configure middleware

import express, { Application } from 'express';
import expressValidator from 'express-validator';

//...

const app: Application = express();
app.use(express.json());

app.use(expressValidator());

//...

app.listen(3000, () => {
    console.log(`App is listening on port: 3000`);
});

Create DTO's

import { AbstractValidatedDto, Joi } from 'express-validator';


export class NewActorDto extends AbstractValidatedDto {
  name!: string;
  personId!: number;
  movieId!: number;

  protected getSchema(): Joi.SchemaMap {
    return {
      name: Joi.string().required().max(100),
      personId: Joi.number().integer().required(),
      movieId: Joi.number().integer().required()
    }
  }
}

Get DTO's in controller

import { Response, Application, Router, NextFunction, Request } from 'express';
import { NewActorDto } from './dto/newActor.dto';
import { Joi } from 'express-validator';
import actorService from './actor.service';



const router: Router = Router();

export const ActorController = (app: Application) => {

    //...

    router.put('/:actorId', async (req: Request, res: Response, next: NextFunction) => {
        try {
            const actorId: number = req.getValidatedParam('actorId', Joi.number().integer());
            const dto: NewActorDto = req.getValidatedBody(NewActorDto);
            await actorService.update(actorId, dto)
            res.send();
        } catch (err) {
            next(err);
        };
    });
    
    //...

    app.use('/actors', router);
}

Validation

All dtos need to extend AbstractValidatedDto class

export abstract class AbstractValidatedDto {
    protected abstract getSchema(): SchemaMap;
    public validate(options: ValidationOptions): any;
}

if needed you can override validate() method and provide own validation strategy but by default you only need to implement getSchema(). All available constraint for getSchema() you can find in joi documentation (https://joi.dev/api/?v=17.4.1).

Example implementation can look like this:

protected getSchema(): Joi.SchemaMap {
      return {
          firstName: Joi.string().required().max(100),
          lastName: Joi.string().required().max(100),
          email: Joi.string().required().email(),
          password: Joi.string().required().min(3).max(100)
      }
  }

IMPORTANT: Object needs to be exactly the same as schema because if it have any additional field, error will be throwed. (can be changed in global settings)

Example class that override validate method

export class NewActorDto extends AbstractValidatedDto {
  name!: string;
  personId!: number;
  movieId!: number;

  protected getSchema(): Joi.SchemaMap {
    return {}
  }

  public validate(options: Joi.ValidationOptions): NewActorDto {
    if (this.name == '3') {
      throw Error('Custom validation.')
    }
    return this;
  }
}

Global settings

You can set Joi validation options when registering middleware.

app.use(expressValidator({
    stripUnknown: false,
    abortEarly: false
}));

List of function added to req

/**
* Validates request body against a schema, returns valid object, and throws if validation fails.
* 
* @param type - the expected class (must override AbstractValidatedDto)
*/
getValidatedBody: <T extends AbstractValidatedDto>(type: { new(): T; }) => T;

/**
* Validates request param value against a schema, returns valid value,
* if validation fails throws error or return @param defaultValue if provided.
* 
* @param paramName - the name of param.
* @param schema - the schema object.
* @param defaultValue - optional value returned if validation fails
*/
getValidatedParam: (paramName: string, schema: AnySchema, defaultValue?: any) => any;

/**
* Validates request query value against a schema, returns valid value,
* if validation fails throws error or return @param defaultValue if provided.
* 
* @param queryName  - the name of query.
* @param schema - the schema object.
* @param defaultValue - optional value returned if validation fails
*/
getValidatedQuery: (queryName: string, schema: AnySchema, defaultValue?: any) => any;

License

The MIT License