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(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
}
};There is available the transformAndValidate function with three overloads:
function transformAndValidate<T extends object>(
classType: ClassType<T>,
jsonString: string,
options?: TransformValidationOptions,
): Promise<T | T[]>;function transformAndValidate<T extends object>(
classType: ClassType<T>,
object: object,
options?: TransformValidationOptions,
): Promise<T>;function transformAndValidate<T extends object>(
classType: ClassType<T>,
array: object[],
options?: TransformValidationOptions,
): Promise<T[]>;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.
If you need sync validation, use transformAndValidateSync function instead (available since v0.4.0). It will synchronously return T or T[], not a Promise.
classType- an class symbol, a constructor function which can be called withnew
type ClassType<T> = {
new (...args: any[]): T;
};-
jsonString- a normal string containing JSON -
object- plain JS object of typeobject(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).
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!
0.9.1
- widen
class-transformerpeer dependency version range to>=0.2.3 - updated all dev dependencies
0.9.0
- bump
class-validatorpeer dependency to version>=0.12.0 - updated TypeScript dependency to version
^3.9.5 - updated all dev dependencies
0.8.0
- updated
class-transformerdependency to version^0.2.3 - updated
class-validatordependency 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-transformerdependency to version^0.2.0
0.6.0
- updated
class-validatordependency to version^0.9.1
0.5.0
- remove deprecated
TransformValdiationOptionsinterface (typo) - updated
class-validatordependency to version^0.8.1andclass-transformerto^0.1.9
0.4.1
- fix
TransformValdiationOptionsinterface name typo (deprecate in favour ofTransformValidationOptions)
0.4.0
- added
transformAndValidateSyncfunction for synchronous validation - changed return type for JSON's transform and validation to
PromiseofTorT[] - updated
class-validatordependency to version^0.7.2andclass-transformerto^0.1.7
0.3.0
- added support for transform and validate array of objects given class
- updated
class-validatordependency 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
- changed throwing error (rejecting promise) from string to
Errorwith message
0.1.0
- initial version with
transformAndValidatefunction
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