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class-transformer-validator
Advanced tools
Readme
A simple plugin for class-transformer and class-validator which combines them in a nice and programmer-friendly API.
npm install class-transformer-validator --save
(or the short way):
npm i -S class-transformer-validator
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:
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(error => {
// here you can handle error on transformation (invalid JSON)
// or validation error (e.g. invalid email property)
console.err(error);
});
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);
// intered type of userObject is User, you can access all class prototype properties and methods
} catch (error) {
// your error handling
console.err(error);
}
}
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 (error) {
// your error handling
}
}
There is available the transformAndValidate
function with three overloads:
function transformAndValidate<T extends object>(classType: ClassType<T>, jsonString: string, options?: TransformValdiationOptions): Promise<T|T[]>;
function transformAndValidate<T extends object>(classType: ClassType<T>, object: object, options?: TransformValdiationOptions): Promise<T>;
function transformAndValidate<T extends object>(classType: ClassType<T>, array: object[], options?: TransformValdiationOptions): Promise<T[]>;
If you need sync validation, use transformAndValidateSync
function instead (since v0.4.0).
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 = transformAndValidate(User, JSON.stringify([{ email: "test@test.test" }])) as User[];
Or you can just check in runtime using Array.isArray(obj)
method.
classType
- an class symbol, a constructor function which can be called with new
type ClassType<T> = {
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 TransformValdiationOptions {
validator?: ValidatorOptions;
transformer?: ClassTransformOptions;
}
You can use it to pass options for class-validator
(more info) and for class-transformer
(more info).
The class-transformer and class-validator are more powerfull than it was showed in the simple usage sample, so go to their github page and check out they capabilities!
0.4.0
transformAndValidateSync
function for synchronous validationPromise
of T
or T[]
class-validator
dependency to version ^0.7.2
and class-transformer
to ^0.1.7
0.3.0
class-validator
dependency to version ^0.7.1
0.2.0
object
(introduced in TS 2.2)0.1.1
Error
with message0.1.0
transformAndValidate
functionFAQs
A simple wrapper around class-transformer and class-validator which provides nice and programmer-friendly API.
We found that class-transformer-validator demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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