Ember.computed Namespace
PUBLIC
Defined in: packages/ember-metal/lib/computed.js:452
Module: ember-metal
This helper returns a new property descriptor that wraps the passed computed property function. You can use this helper to define properties with mixins or via Ember.defineProperty()
.
If you pass a function as an argument, it will be used as a getter. A computed property defined in this way might look like this:
let Person = Ember.Object.extend({ init() { this._super(...arguments); this.firstName = 'Betty'; this.lastName = 'Jones'; }, fullName: Ember.computed('firstName', 'lastName', function() { return `${this.get('firstName')} ${this.get('lastName')}`; }) }); let client = Person.create(); client.get('fullName'); // 'Betty Jones' client.set('lastName', 'Fuller'); client.get('fullName'); // 'Betty Fuller'
You can pass a hash with two functions, get
and set
, as an argument to provide both a getter and setter:
let Person = Ember.Object.extend({ init() { this._super(...arguments); this.firstName = 'Betty'; this.lastName = 'Jones'; }, fullName: Ember.computed('firstName', 'lastName', { get(key) { return `${this.get('firstName')} ${this.get('lastName')}`; }, set(key, value) { let [firstName, lastName] = value.split(/\s+/); this.setProperties({ firstName, lastName }); return value; } }); }) let client = Person.create(); client.get('firstName'); // 'Betty' client.set('fullName', 'Carroll Fuller'); client.get('firstName'); // 'Carroll'
The set
function should accept two parameters, key
and value
. The value returned from set
will be the new value of the property.
Note: This is the preferred way to define computed properties when writing third-party libraries that depend on or use Ember, since there is no guarantee that the user will have prototype Extensions enabled.
The alternative syntax, with prototype extensions, might look like:
fullName: function() { return this.get('firstName') + ' ' + this.get('lastName'); }.property('firstName', 'lastName')
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