Class Ember.computed
publicThis 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:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 |
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')} ${this.get('lastName')}`; }) }); let client = Person.create(); client.get('fullName'); // 'Betty Jones' client.set('lastName', 'Fuller'); client.get('fullName'); // 'Betty Fuller' |
You can pass a hash with two functions, get
and set
, as an
argument to provide both a getter and setter:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 |
let Person = Ember.Object.extend({ init() { this._super(...arguments); this.firstName = 'Betty'; this.lastName = 'Jones'; }, fullName: Ember.computed('firstName', 'lastName', { get(key) { return `${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:
1 2 3 |
fullName: function() { return this.get('firstName') + ' ' + this.get('lastName'); }.property('firstName', 'lastName') |