ember-computed-decorators

This addon allows usage of the proposed decorator syntax, and passes the specified dependent keys into your computed function making your computed properties much DRY'er.

More details:

• javascript-decorators proposal
• babel blog post

Usage

Babel Setup

To use ember-computed-decorators you must update Babel's configuration to allow usage of the decorator proposal.

As of Babel 5.1.0 the following should be all you need in your ember-cli application:

• pre-1.13.0

// Brocfile.js
var app = new EmberApp({
  babel: {
    optional: ['es7.decorators']
  }
});

• 1.13.x

// ember-cli-build.js
var app = new EmberApp({
  babel: {
    optional: ['es7.decorators']
  }
});

Setup with addon

Add the following init method to index.js of your addon. This should enable the decorators to work on the parent app/addon.

  init: function(app) {
    this._super.init && this._super.init.apply(this, arguments);
 
    this.options = this.options || {};
    this.options.babel = this.options.babel || {};
    this.options.babel.optional = this.options.babel.optional || [];
 
    if (this.options.babel.optional.indexOf('es7.decorators') === -1) {
      this.options.babel.optional.push('es7.decorators');
    }
  }

Application Usage

With Dependent Keys

In your application where you would normally have:

foo: Ember.computed('someKey', 'otherKey', function() {
  var someKey = this.get('someKey');
  var otherKey = this.get('otherKey');
 
  // Do Stuff
})

You replace with this:

import computed from 'ember-computed-decorators';
 
// ..... <snip> .....
@computed('someKey', 'otherKey')
foo(someKey, otherKey) {
  // Do Stuff
}

Without Dependent Keys

foo: Ember.computed(function() {
  // Do Stuff
})

You replace with this:

import computed from 'ember-computed-decorators';
 
// ..... <snip> .....
@computed
foo() {
  // Do Stuff
}

"Real World"

import Ember from 'ember';
import computed from 'ember-computed-decorators';
 
export default Ember.Component.extend({
  @computed('first', 'last')
  name(first, last) {
    return `${first} ${last}`;
  }
});

"Real World get/set syntax"

import Ember from 'ember';
import computed from 'ember-computed-decorators';
 
export default Ember.Component.extend({
  @computed('first', 'last')
  name: {
    get(first, last) {
      return `${first} ${last}`;
    },
 
    set(value, first, last) {
      // ...
    }
  }
});

"readOnly"

import Ember from 'ember';
import computed, { readOnly } from 'ember-computed-decorators';
 
export default Ember.Component.extend({
  @readOnly
  @computed('first', 'last')
  name(first, last) {
    return `${first} ${last}`;
  }
});

Enumerables / Arrays

When a computed property key contains @each, [] (enumerable) then the argument that is passed to the get or set method will be the object at the path up to the @each or [] part.

import Ember from 'ember';
import computed from 'ember-computed-decorators';
 
export default Ember.Component.extend({
  persons: [
    { first: 'David', last: 'Heinemeier Hansson' },
    { first: 'Aaron', last: 'Patterson' }
  ],
 
  @computed('persons.@each.{first,last}')
  names(persons) {
    return persons.map((person) => `${person.first} ${person.last}`);
  }
});

Property Expansion

When a computed property key contains {foo,bar} then the arguments that are passed to the get or set method will get the expanded properties.

import Ember from 'ember';
import computed from 'ember-computed-decorators';
 
export default Ember.Component.extend({
  address: {
    street: 'Pennsylvania Avenue',
    number: 1600
  },
 
  @computed('address.{street,number}')
  formattedStreet(street, number) {
    return `${number} ${street}`;
  }
});

ember-data

import DS from 'ember-data';
import {
  attr,
  hasMany
} from "ember-computed-decorators/ember-data";
 
export default DS.Model.extend({
  @attr firstName,
  @hasMany users
});
 

Computed Macros

All of the computed macros are also available for use.

alias

Creates a new property that is an alias for another property on an object. Calls to get or set this property behave as though they were called on the original property.

import Ember from 'ember';
import { alias } from 'ember-computed-decorators';
export default Ember.Component.extend({
  person: {
    first: 'Joe'
  },
 
  @alias('person.first') firstName
});

and

A computed property that performs a logical and on the original values for the provided dependent properties.

import Ember from 'ember';
import { and } from 'ember-computed-decorators';
export default Ember.Component.extend({
  person: {
    first: 'Joe'
  },
 
  @and('first', 'last') hasFullName // false
});

bool

A computed property that converts the provided dependent property into a boolean value.

import Ember from 'ember';
import { bool } from 'ember-computed-decorators';
export default Ember.Component.extend({
  messageCount: 1,
 
  @bool('messageCount') hasMessages // true
});

collect

A computed property that returns the array of values for the provided dependent properties.

import Ember from 'ember';
import { collect } from 'ember-computed-decorators';
export default Ember.Component.extend({
  light: 'strobe',
  lens: '35mm prime',
 
  @collect('light', 'lens') equipment // ['strobe', '35mm prime']
});

empty

A computed property that returns true if the value of the dependent property is null, an empty string, empty array, or empty function.

import Ember from 'ember';
import { empty } from 'ember-computed-decorators';
export default Ember.Component.extend({
  items: Ember.A(['taco', 'burrito']),
 
  @empty('items') isEmpty // false
});

equal

import Ember from 'ember';
import { equal } from 'ember-computed-decorators';
export default Ember.Component.extend({
  state: 'sleepy',
 
  @equal('state', 'sleepy') napTime // true
});

filter

Filters the array by the callback.

The callback method you provide should have the following signature. item is the current item in the iteration. index is the integer index of the current item in the iteration. array is the dependant array itself.

function(item, index, array)

import Ember from 'ember';
import { filter } from 'ember-computed-decorators';
export default Ember.Component.extend({
  chores: Ember.A([
    { name: 'cook', done: true },
    { name: 'clean', done: true },
    { name: 'write more unit tests', done: false }
  ]),
 
  @filter('chores', function(chore, index, array) {
    return !chore.done;
  }) remainingChores // [{name: 'write more unit tests', done: false}]
});

filterBy

Filters the array by the property and value.

import Ember from 'ember';
import { filterBy } from 'ember-computed-decorators';
export default Ember.Component.extend({
  chores: Ember.A([
    { name: 'cook', done: true },
    { name: 'clean', done: true },
    { name: 'write more unit tests', done: false }
  ]),
 
  @filterBy('chores', 'done', false) remainingChores // [{name: 'write more unit tests', done: false}]
});

gt

A computed property that returns true if the provided dependent property is greater than the provided value.

import Ember from 'ember';
import { gt } from 'ember-computed-decorators';
export default Ember.Component.extend({
  totalCats: 11,
 
  @gt('totalCats', 10) isCatParty // true
});

gte

A computed property that returns true if the provided dependent property is greater than or equal to the provided value.

import Ember from 'ember';
import { gte } from 'ember-computed-decorators';
export default Ember.Component.extend({
  totalPlayers: 14,
 
  @gte('totalPlayers', 14) hasEnoughPlayers // true
});

intersect

A computed property which returns a new array with all the duplicated elements from two or more dependent arrays.

import Ember from 'ember';
import { intersect } from 'ember-computed-decorators';
export default Ember.Component.extend({
  likes: Ember.A([ 'tacos', 'puppies', 'pizza' ]),
  foods: Ember.A(['tacos', 'pizza']),
 
  @intersect('likes', 'foods') favoriteFoods // ['tacos', 'pizza']
});

lt

A computed property that returns true if the provided dependent property is less than the provided value.

import Ember from 'ember';
import { lt } from 'ember-computed-decorators';
export default Ember.Component.extend({
  totalDogs: 3,
 
  @lt('totalDogs', 10) isDogParty // true
});

lte

A computed property that returns true if the provided dependent property is less than or equal to the provided value.

import Ember from 'ember';
import { lte } from 'ember-computed-decorators';
export default Ember.Component.extend({
  totalPlayers: 14,
 
  @lte('totalPlayers', 14) hasEnoughPlayers // true
});

map

Returns an array mapped via the callback

The callback method you provide should have the following signature. item is the current item in the iteration. index is the integer index of the current item in the iteration.

function(item, index);

import Ember from 'ember';
import { map } from 'ember-computed-decorators';
export default Ember.Component.extend({
  chores: Ember.A(['clean', 'write more unit tests']),
 
  @map('chores', function(chore, index) {
    return chore.toUpperCase() + '!';
  }) loudChores // ['CLEAN!', 'WRITE MORE UNIT TESTS!']
});

mapBy

Returns an array mapped to the specified key.

import Ember from 'ember';
import { mapBy } from 'ember-computed-decorators';
export default Ember.Component.extend({
  people: Ember.A([
    {name: "George", age: 5},
    {name: "Stella", age: 10},
    {name: "Violet", age: 7}
  ]),
 
  @mapBy('people', 'age') ages // [5, 10, 7]
});

match

A computed property which matches the original value for the dependent property against a given RegExp, returning true if they values matches the RegExp and false if it does not.

import Ember from 'ember';
import { match } from 'ember-computed-decorators';
export default Ember.Component.extend({
  email: '[e-mail]',
 
  @match('email', /^.+@.+\..+$/) validEmail
});

max

A computed property that calculates the maximum value in the dependent array. This will return -Infinity when the dependent array is empty.

import Ember from 'ember';
import { max } from 'ember-computed-decorators';
export default Ember.Component.extend({
  values: Ember.A([1, 2, 5, 10]),
 
  @max('values') maxValue // 10
});

min

A computed property that calculates the minimum value in the dependent array. This will return Infinity when the dependent array is empty.

import Ember from 'ember';
import { min } from 'ember-computed-decorators';
export default Ember.Component.extend({
  values: Ember.A([1, 2, 5, 10]),
 
  @min('values') minValue // 1
});

none

A computed property that returns true if the value of the dependent property is null or undefined. This avoids errors from JSLint complaining about use of ==, which can be technically confusing.

import Ember from 'ember';
import { none } from 'ember-computed-decorators';
export default Ember.Component.extend({
  firstName: null,
 
  @none('firstName') isNameless // true until firstName is defined
});

not

A computed property that returns the inverse boolean value of the original value for the dependent property.

import Ember from 'ember';
import { not } from 'ember-computed-decorators';
export default Ember.Component.extend({
  loggedIn: false,
 
  @not('loggedIn') isAnonymous // true
});

notEmpty

A computed property that returns true if the value of the dependent property is NOT null, an empty string, empty array, or empty function.

import Ember from 'ember';
import { notEmpty } from 'ember-computed-decorators';
export default Ember.Component.extend({
  groceryBag: Ember.A(['milk', 'eggs', 'apples']),
 
  @notEmpty('groceryBag') hasGroceriesToPutAway // true
});

oneWay

Where computed.alias aliases get and set, and allows for bidirectional data flow, computed.oneWay only provides an aliased get. The set will not mutate the upstream property, rather causes the current property to become the value set. This causes the downstream property to permanently diverge from the upstream property.

import Ember from 'ember';
import { oneWay } from 'ember-computed-decorators';
export default Ember.Component.extend({
  firstName: 'Joe',
 
  @oneWay('firstName') originalName // will always be 'Joe'
});

or

A computed property which performs a logical or on the original values for the provided dependent properties.

import Ember from 'ember';
import { or } from 'ember-computed-decorators';
export default Ember.Component.extend({
  hasJacket: true,
  hasUmbrella: false,
 
  @or('hasJacket', 'hasUmbrella') isReadyForRain // true
});

readOnly

Where computed.oneWay provides oneWay bindings, computed.readOnly provides a readOnly one way binding. Very often when using computed.oneWay one does not also want changes to propagate back up, as they will replace the value.

This prevents the reverse flow, and also throws an exception when it occurs.

import Ember from 'ember';
import { readOnly, alias } from 'ember-computed-decorators';
export default Ember.Component.extend({
  @readOnly @alias('first') firstName // throws an error if set 'firstName' is attempted
});

reads

This is a more semantically meaningful alias of computed.oneWay, whose name is somewhat ambiguous as to which direction the data flows.

import Ember from 'ember';
import { reads } from 'ember-computed-decorators';
export default Ember.Component.extend({
  @reads('first') firstName
});

setDiff

A computed property which returns a new array with all the properties from the first dependent array that are not in the second dependent array.

import Ember from 'ember';
import { setDiff } from 'ember-computed-decorators';
export default Ember.Component.extend({
  likes: Ember.A([ 'tacos', 'puppies', 'pizza' ]),
  foods: Ember.A(['tacos', 'pizza']),
 
  @setDiff('likes', 'foods') favoriteThingsThatArentFood // ['puppies']
});

sort

A computed property which returns a new array with all the properties from the first dependent array sorted based on a property or sort function.

The callback method you provide should have the following signature:

function(itemA, itemB);

itemA the first item to compare. itemB the second item to compare.

This function should return negative number (e.g. -1) when itemA should come before itemB. It should return positive number (e.g. 1) when itemA should come after itemB. If the itemA and itemB are equal this function should return 0.

Therefore, if this function is comparing some numeric values, simple itemA - itemB or itemA.get( 'foo' ) - itemB.get( 'foo' ) can be used instead of series of if.

import Ember from 'ember';
import { sort } from 'ember-computed-decorators';
export default Ember.Component.extend({
  this.names = Ember.A([{name:'Link'},{name:'Zelda'},{name:'Gannon'},{name:'Navi'}]);
  @sort('names', function(a, b){
    if (a.name > b.name) {
      return 1;
    } else if (a.name < b.name) {
      return -1;
    }
 
    return 0;
  }) sortedNames // [{name:'Gannon'},{name:'Link'},{name:'Navi'},{name:'Zelda'}]
});

sum

A computed property that returns the sum of the value in the dependent array.

import Ember from 'ember';
import { sum } from 'ember-computed-decorators';
export default Ember.Component.extend({
  values: Ember.A([1, 2, 3]),
 
  @sum('values') total // 6
});

union

Alias for uniq.

import Ember from 'ember';
import { union } from 'ember-computed-decorators';
export default Ember.Component.extend({
  likes: Ember.A([ 'tacos', 'puppies', 'pizza' ]),
  foods: Ember.A(['tacos', 'pizza', 'ramen']),
 
  @union('likes', 'foods') favorites // ['tacos', 'puppies', 'pizza', 'ramen']
});

uniq

A computed property which returns a new array with all the unique elements from one or more dependent arrays.

import Ember from 'ember';
import { uniq } from 'ember-computed-decorators';
export default Ember.Component.extend({
  likes: Ember.A([ 'tacos', 'puppies', 'pizza' ]),
  foods: Ember.A(['tacos', 'pizza', 'ramen']),
 
  @uniq('likes', 'foods') favorites // ['tacos', 'puppies', 'pizza', 'ramen']
});

Installation

• git clone <repository-url> this repository
• cd ember-computed-decorators
• npm install
• bower install

Running

• ember serve
• Visit your app at http://localhost:4200.

Running Tests

• npm test (Runs ember try:each to test your addon against multiple Ember versions)
• ember test
• ember test --server

Building

• ember build

For more information on using ember-cli, visit https://ember-cli.com/.