decorate-all

A typescript decorator that allows you to apply another decorator to all methods of a class.

npm i decorate-all

Note: since version 1.1.0, this package uses the reflect-metadata package as a peer dependency, so you need to have it installed.

Why

A need for this decorator arose from having to decorate all methods (route handlers) of a NestJS controller class with the same parameter decorator. In the project, which is a multi-tenant application, most routes include a "tenantId" path parameter which needed to be specified using a route decorator. Repeating it over each method was tedious and error prone.

Thus, decorate-all was born.

Usage

import { DecorateAll } from 'decorate-all';

const Uppercase = (
    target: any,
    propertyKey: string,
    descriptor: PropertyDescriptor,
) => {
    const original = descriptor.value;
    descriptor.value = function () {
        return original.call(this).toUpperCase();
    };
};

// instead of decorating each method on its own...
class Hello1 {
    @Uppercase
    world() {
        return 'world';
    }

    @Uppercase
    galaxy() {
        return 'galaxy';
    }
}

// ...use the DecorateAll decorator
@DecorateAll(Uppercase)
class Hello2 {
    world() {
        return 'world';
    }
    galaxy() {
        return 'galaxy';
    }
}

const hello1 = new Hello1();
console.log(hello1.world()); // logs "WORLD"
console.log(hello1.galaxy()); // logs "GALAXY"

const hello2 = new Hello2();
console.log(hello2.world()); // logs "WORLD"
console.log(hello2.galaxy()); // logs "GALAXY"

Options

The second parameter of the DecorateAll decorator takes an options object with the following options:

• exclude: string[]
  array of method names that won't be decorated

// apply the Uppercase decorator to all methods, except 'galaxy'
@DecorateAll(Uppercase, { exclude: ['galaxy'] })
class Hello {
    world() {
        return 'world';
    }
    galaxy() {
        return 'galaxy';
    }
    universe() {
        return 'universe';
    }
}

const hello = new Hello();
console.log(hello.world()); // logs "WORLD"
console.log(hello.galaxy()); // logs "galaxy"
console.log(hello.universe()); // logs "UNIVERSE"

• deep: boolean
  By default, only the class' own methods are decorated. If you pass deep: true, the decorator will be also applied to inherited methods of any extended class. (It can also be combined with the exclude option).

class Plain {
    hi() {
        return 'hi';
    }
    hello() {
        return 'hello';
    }
}

@DecorateAll(Uppercase, { deep: true })
class Decorated extends Plain {}

const plain = new Plain();
console.log(plain.hi()); // logs "hi"
console.log(plain.hello()); // logs "hello"

const decorated = new Decorated();
console.log(decorated.hi()); // logs "HI"
console.log(decorated.hello()); // logs "HELLO"