Need help with class-transformer-validator?
Click the “chat” button below for chat support from the developer who created it, or find similar developers for support.

About the developer

MichalLytek
148 Stars 13 Forks MIT License 37 Commits 5 Opened issues

Description

A simple plugin for class-transformer and class-validator which combines them in a nice and programmer-friendly API.

Services available

!
?

Need anything else?

Contributors list

# 5,104
GraphQL
graphql...
sqlserv...
Electro...
34 commits
# 401,846
TypeScr...
JavaScr...
viml
Vim
2 commits

class-transformer-validator

npm version Dependency Status devDependency Status peerDependency Status

A simple plugin for class-transformer and class-validator which combines them in a nice and programmer-friendly API.

Installation

Module installation

npm install class-transformer-validator --save

(or the short way):

npm i -S class-transformer-validator

Peer dependencies

This package is only a simple plugin/wrapper, so you have to install the required modules too because it can't work without them. See detailed installation instruction for the modules installation:

Usage

The usage of this module is very simple.

import { IsEmail } from "class-validator";
import { transformAndValidate } from "class-transformer-validator";

// declare the class using class-validator decorators class User { @IsEmail() public email: string;

public hello(): string { return "World!"; } }

// then load the JSON string from any part of your app const userJson: string = loadJsonFromSomething();

// transform the JSON to class instance and validate it correctness transformAndValidate(User, userJson) .then((userObject: User) => { // now you can access all your class prototype method console.log(Hello ${userObject.hello()}); // prints "Hello World!" on console }) .catch(err => { // here you can handle error on transformation (invalid JSON) // or validation error (e.g. invalid email property) console.error(err); });

You can also transform and validate plain JS object (e.g. from express req.body). Using ES7 async/await syntax:

async (req, res) => {
  try {
    // transform and validate request body
    const userObject = await transformAndValidate(User, req.body);
    // infered type of userObject is User, you can access all class prototype properties and methods
  } catch (err) {
    // your error handling
    console.error(err);
  }
};

And since release

0.3.0
you can also pass array of objects - all of them will be validated using given class validation constraints:
async (req, res) => {
  try {
    // transform and validate request body - array of User objects
    const userObjects = await transformAndValidate(User, req.body);
    userObjects.forEach(user => console.log(`Hello ${user.hello()}`));
  } catch (err) {
    // your error handling
  }
};

API reference

Function signatures

There is available the

transformAndValidate
function with three overloads:
function transformAndValidate(
  classType: ClassType,
  jsonString: string,
  options?: TransformValidationOptions,
): Promise;
function transformAndValidate(
  classType: ClassType,
  object: object,
  options?: TransformValidationOptions,
): Promise;
function transformAndValidate(
  classType: ClassType,
  array: object[],
  options?: TransformValidationOptions,
): Promise;

Be aware that if you validate json string, the return type is a

Promise
of
T
or
T[]
so you need to assert the returned type if you know the shape of json:
const users = (await transformAndValidate(
  User,
  JSON.stringify([{ email: "[email protected]" }]),
)) as User[];

Or you can just check the type in runtime using

Array.isArray
method.

Synchronous transformation and validation

If you need sync validation, use

transformAndValidateSync
function instead (available since v0.4.0). It will synchronously return
T
or
T[]
, not a Promise.

Parameters and types

  • classType
    - an class symbol, a constructor function which can be called with
    new
type ClassType = {
  new (...args: any[]): T;
};
  • jsonString
    - a normal string containing JSON
  • object
    - plain JS object of type
    object
    (introduced in TypeScript 2.2), you will have compile-time error while trying to pass number, boolean, null or undefined but unfortunately run-time error when passing a function
  • array
    - array of plain JS objects like described above
  • options
    - optional options object, it has two optional properties
interface TransformValidationOptions {
  validator?: ValidatorOptions;
  transformer?: ClassTransformOptions;
}

You can use it to pass options for

class-validator
(more info) and for
class-transformer
(more info).

More info

The class-transformer and class-validator are more powerful than it was showed in the simple usage sample, so go to their github page and check out they capabilities!

Release notes

0.9.1

  • widen
    class-transformer
    peer dependency version range to
    >=0.2.3
  • updated all dev dependencies

0.9.0

  • bump
    class-validator
    peer dependency to version
    >=0.12.0
  • updated TypeScript dependency to version
    ^3.9.5
  • updated all dev dependencies

0.8.0

  • updated
    class-transformer
    dependency to version
    ^0.2.3
  • updated
    class-validator
    dependency to version
    ^0.10.1
  • updated TypeScript dependency to version
    ^3.6.3
  • built code is now emitted as ES2015 (dropped es5 support)
  • updated all dev dependencies

0.7.1

  • updated
    class-transformer
    dependency to version
    ^0.2.0

0.6.0

  • updated
    class-validator
    dependency to version
    ^0.9.1

0.5.0

  • remove deprecated
    TransformValdiationOptions
    interface (typo)
  • updated
    class-validator
    dependency to version
    ^0.8.1
    and
    class-transformer
    to
    ^0.1.9

0.4.1

  • fix
    TransformValdiationOptions
    interface name typo (deprecate in favour of
    TransformValidationOptions
    )

0.4.0

  • added
    transformAndValidateSync
    function for synchronous validation
  • changed return type for JSON's transform and validation to
    Promise
    of
    T
    or
    T[]
  • updated
    class-validator
    dependency to version
    ^0.7.2
    and
    class-transformer
    to
    ^0.1.7

0.3.0

  • added support for transform and validate array of objects given class
  • updated
    class-validator
    dependency to version
    ^0.7.1

0.2.0

  • changed object parameter type declaration to
    object
    (introduced in TS 2.2)
  • throwing error when passed array, undefined or null

0.1.1

0.1.0

  • initial version with
    transformAndValidate
    function

We use cookies. If you continue to browse the site, you agree to the use of cookies. For more information on our use of cookies please see our Privacy Policy.