@mattinsler/garnish

A useful group of decorators

Installation

$ npm install --save @mattinsler/garnish

Usage

@concurrent(max-concurrent-executions)

Only allow a certain number of concurrent calls to a method. If the method returns a promise, only max-concurrent-executions executions of that method can be running at the same time. If the method is called more times concurrently, an Error will be thrown.

import { concurrent } from '@mattinsler/garnish'

class Foo {
  @concurrent(1)
  async update() {
    // do something that takes long
  }
}

@memoize

Ensure that a method is only called once per class instance. The return value is saved and returned for all future calls. In order to not allow for accidental RAM abuse, this will only work for methods that do not take any parameters.

import { memoize } from '@mattinsler/garnish'

class Foo {
  @memoize
  getConnection() {
    // establish connection and return a promise
  }

  async update() {
    const connection = await this.getConnection();
    // use connection
  }
}

@omit(...fields)

Remove fields from the return object. This will work for return values that are plain objects or promises that return plain objects. This will also work for single return values or arrays.

import { omit } from '@mattinsler/garnish'

class User {
  @omit('_id', 'password')
  find(query) {
    return UserModel.find(query);
  }

  @omit('_id', 'password')
  findOne(query) {
    return UserModel.findOne(query);
  }
}

@view(viewConfigObject)

Mutates fields in the return object according to the viewConfigObject. This will work for return values that are plain objects or promises that return plain objects.

There are 4 types of operations that you can use with the @view decorator.

• Copy: { 'to-key': 'from-key' }
• Rename: { 'to-key': '!from-key' }
• Delete: { key: 0 } or { key: false }
• Compute: { key: (object) => object.foo.bar * 3 }

You can use any combination of operations in a single declaration. You can also specify nested objects using . as a delimiter in either the key or value.

import { view } from '@mattinsler/garnish'

class User {
  @view({
    id: '!_id',      // rename _id to id
    password: false  // delete password
    name: (user) => `${user.firstName} ${user.lastName}`, // compute name
    'accounts.github': 'github'  // copy { github } to { accounts: { github }}
  })
  findOne(query) {
    return UserModel.findOne(query);
  }
}