Class Ember.Engine

public

The Engine class contains core functionality for both applications and engines.

Each engine manages a registry that's used for dependency injection and exposed through RegistryProxy.

Engines also manage initializers and instance initializers.

Engines can spawn EngineInstance instances via buildInstance().

Show:

Module: ember

Available since v2.14.1

key
String
The key to observe
target
Object
The target object to invoke
method
String|Function
The method to invoke

Adds an observer on a property.

This is the core method used to register an observer for a property.

Once you call this method, any time the key's value is set, your observer will be notified. Note that the observers are triggered any time the value is set, regardless of whether it has actually changed. Your observer should be prepared to handle that.

Observer Methods

Observer methods have the following signature:

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export default Ember.Component.extend({
  init() {
    this._super(...arguments);
    this.addObserver('foo', this, 'fooDidChange');
  },

  fooDidChange(sender, key, value, rev) {
    // your code
  }
});

The sender is the object that changed. The key is the property that changes. The value property is currently reserved and unused. The rev is the last property revision of the object when it changed, which you can use to detect if the key value has really changed or not.

Usually you will not need the value or revision parameters at the end. In this case, it is common to write observer methods that take only a sender and key value as parameters or, if you aren't interested in any of these values, to write an observer that has no parameters at all.

Module: ember

Available since v2.14.1

keyName
String
returns
Object
The cached value of the computed property, if any

Returns the cached value of a computed property, if it exists. This allows you to inspect the value of a computed property without accidentally invoking it if it is intended to be generated lazily.

Module: ember

Available since v2.14.1

arguments

Creates an instance of a class. Accepts either no arguments, or an object containing values to initialize the newly instantiated object with.

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const Person = Ember.Object.extend({
  helloWorld() {
    alert(`Hi, my name is ${this.get('name')}`);
  }
});

let tom = Person.create({
  name: 'Tom Dale'
});

tom.helloWorld(); // alerts "Hi, my name is Tom Dale".

create will call the init function if defined during Ember.AnyObject.extend

If no arguments are passed to create, it will not set values to the new instance during initialization:

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let noName = Person.create();
noName.helloWorld(); // alerts undefined

NOTE: For performance reasons, you cannot declare methods or computed properties during create. You should instead declare methods and computed properties when using extend.

Module: ember

Available since v2.14.1

keyName
String
The name of the property to decrement
decrement
Number
The amount to decrement by. Defaults to 1
returns
Number
The new property value

Set the value of a property to the current value minus some amount.

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player.decrementProperty('lives');
orc.decrementProperty('health', 5);
Module: ember

Available since v2.14.1

returns
Ember.Object
receiver

Destroys an object by setting the isDestroyed flag and removing its metadata, which effectively destroys observers and bindings.

If you try to set a property on a destroyed object, an exception will be raised.

Note that destruction is scheduled for the end of the run loop and does not happen immediately. It will set an isDestroying flag immediately.

Module: ember

Available since v2.14.1

mixins
Mixin
One or more Mixin classes
arguments
Object
Object containing values to use within the new class

Creates a new subclass.

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const Person = Ember.Object.extend({
  say(thing) {
    alert(thing);
   }
});

This defines a new subclass of Ember.Object: Person. It contains one method: say().

You can also create a subclass from any existing class by calling its extend() method. For example, you might want to create a subclass of Ember's built-in Ember.Component class:

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const PersonComponent = Ember.Component.extend({
  tagName: 'li',
  classNameBindings: ['isAdministrator']
});

When defining a subclass, you can override methods but still access the implementation of your parent class by calling the special _super() method:

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const Person = Ember.Object.extend({
  say(thing) {
    let name = this.get('name');
    alert(`${name} says: ${thing}`);
  }
});

const Soldier = Person.extend({
  say(thing) {
    this._super(`${thing}, sir!`);
  },
  march(numberOfHours) {
    alert(`${this.get('name')} marches for ${numberOfHours} hours.`);
  }
});

let yehuda = Soldier.create({
  name: 'Yehuda Katz'
});

yehuda.say('Yes');  // alerts "Yehuda Katz says: Yes, sir!"

The create() on line #17 creates an instance of the Soldier class. The extend() on line #8 creates a subclass of Person. Any instance of the Person class will not have the march() method.

You can also pass Mixin classes to add additional properties to the subclass.

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const Person = Ember.Object.extend({
  say(thing) {
    alert(`${this.get('name')} says: ${thing}`);
  }
});

const SingingMixin = Mixin.create({
  sing(thing){
    alert(`${this.get('name')} sings: la la la ${thing}`);
  }
});

const BroadwayStar = Person.extend(SingingMixin, {
  dance() {
    alert(`${this.get('name')} dances: tap tap tap tap `);
  }
});

The BroadwayStar class contains three methods: say(), sing(), and dance().

Module: ember

Available since v2.14.1

keyName
String
The property to retrieve
returns
Object
The property value or undefined.

Retrieves the value of a property from the object.

This method is usually similar to using object[keyName] or object.keyName, however it supports both computed properties and the unknownProperty handler.

Because get unifies the syntax for accessing all these kinds of properties, it can make many refactorings easier, such as replacing a simple property with a computed property, or vice versa.

Computed Properties

Computed properties are methods defined with the property modifier declared at the end, such as:

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fullName: Ember.computed('firstName', 'lastName', function() {
  return this.get('firstName') + ' ' + this.get('lastName');
})

When you call get on a computed property, the function will be called and the return value will be returned instead of the function itself.

Unknown Properties

Likewise, if you try to call get on a property whose value is undefined, the unknownProperty() method will be called on the object. If this method returns any value other than undefined, it will be returned instead. This allows you to implement "virtual" properties that are not defined upfront.

Module: ember

Available since v2.14.1

list
String...|Array
of keys to get
returns
Object

To get the values of multiple properties at once, call getProperties with a list of strings or an array:

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record.getProperties('firstName', 'lastName', 'zipCode');
// { firstName: 'John', lastName: 'Doe', zipCode: '10011' }

is equivalent to:

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record.getProperties(['firstName', 'lastName', 'zipCode']);
// { firstName: 'John', lastName: 'Doe', zipCode: '10011' }
Module: ember

Available since v2.14.1

keyName
String
The name of the property to retrieve
defaultValue
Object
The value to return if the property value is undefined
returns
Object
The property value or the defaultValue.

Retrieves the value of a property, or a default value in the case that the property returns undefined.

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person.getWithDefault('lastName', 'Doe');
Module: ember

Available since v2.14.1

keyName
String
The name of the property to increment
increment
Number
The amount to increment by. Defaults to 1
returns
Number
The new property value

Set the value of a property to the current value plus some amount.

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person.incrementProperty('age');
team.incrementProperty('score', 2);
Module: ember

Available since v2.14.1

An overridable method called when objects are instantiated. By default, does nothing unless it is overridden during class definition.

Example:

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const Person = Ember.Object.extend({
  init() {
    alert(`Name is ${this.get('name')}`);
  }
});

let steve = Person.create({
  name: 'Steve'
});

// alerts 'Name is Steve'.

NOTE: If you do override init for a framework class like Ember.View, be sure to call this._super(...arguments) in your init declaration! If you don't, Ember may not have an opportunity to do important setup work, and you'll see strange behavior in your application.

Module: ember

Available since v2.14.1

initializer
Object

The goal of initializers should be to register dependencies and injections. This phase runs once. Because these initializers may load code, they are allowed to defer application readiness and advance it. If you need to access the container or store you should use an InstanceInitializer that will be run after all initializers and therefore after all code is loaded and the app is ready.

Initializer receives an object which has the following attributes: name, before, after, initialize. The only required attribute is initialize, all others are optional.

  • name allows you to specify under which name the initializer is registered. This must be a unique name, as trying to register two initializers with the same name will result in an error.
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Ember.Application.initializer({
  name: 'namedInitializer',

  initialize: function(application) {
    Ember.debug('Running namedInitializer!');
  }
});
  • before and after are used to ensure that this initializer is ran prior or after the one identified by the value. This value can be a single string or an array of strings, referencing the name of other initializers.

An example of ordering initializers, we create an initializer named first:

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Ember.Application.initializer({
  name: 'first',

  initialize: function(application) {
    Ember.debug('First initializer!');
  }
});

// DEBUG: First initializer!

We add another initializer named second, specifying that it should run after the initializer named first:

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Ember.Application.initializer({
  name: 'second',
  after: 'first',

  initialize: function(application) {
    Ember.debug('Second initializer!');
  }
});

// DEBUG: First initializer!
// DEBUG: Second initializer!

Afterwards we add a further initializer named pre, this time specifying that it should run before the initializer named first:

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Ember.Application.initializer({
  name: 'pre',
  before: 'first',

  initialize: function(application) {
    Ember.debug('Pre initializer!');
  }
});

// DEBUG: Pre initializer!
// DEBUG: First initializer!
// DEBUG: Second initializer!

Finally we add an initializer named post, specifying it should run after both the first and the second initializers:

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Ember.Application.initializer({
  name: 'post',
  after: ['first', 'second'],

  initialize: function(application) {
    Ember.debug('Post initializer!');
  }
});

// DEBUG: Pre initializer!
// DEBUG: First initializer!
// DEBUG: Second initializer!
// DEBUG: Post initializer!
  • initialize is a callback function that receives one argument, application, on which you can operate.

Example of using application to register an adapter:

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Ember.Application.initializer({
  name: 'api-adapter',

  initialize: function(application) {
    application.register('api-adapter:main', ApiAdapter);
  }
});
Module: ember

Available since v2.14.1

instanceInitializer

Instance initializers run after all initializers have run. Because instance initializers run after the app is fully set up. We have access to the store, container, and other items. However, these initializers run after code has loaded and are not allowed to defer readiness.

Instance initializer receives an object which has the following attributes: name, before, after, initialize. The only required attribute is initialize, all others are optional.

  • name allows you to specify under which name the instanceInitializer is registered. This must be a unique name, as trying to register two instanceInitializer with the same name will result in an error.
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Ember.Application.instanceInitializer({
  name: 'namedinstanceInitializer',

  initialize: function(application) {
    Ember.debug('Running namedInitializer!');
  }
});
  • before and after are used to ensure that this initializer is ran prior or after the one identified by the value. This value can be a single string or an array of strings, referencing the name of other initializers.

  • See Ember.Application.initializer for discussion on the usage of before and after.

Example instanceInitializer to preload data into the store.

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Ember.Application.initializer({
  name: 'preload-data',

  initialize: function(application) {
    var userConfig, userConfigEncoded, store;
    // We have a HTML escaped JSON representation of the user's basic
    // configuration generated server side and stored in the DOM of the main
    // index.html file. This allows the app to have access to a set of data
    // without making any additional remote calls. Good for basic data that is
    // needed for immediate rendering of the page. Keep in mind, this data,
    // like all local models and data can be manipulated by the user, so it
    // should not be relied upon for security or authorization.
    //
    // Grab the encoded data from the meta tag
    userConfigEncoded = Ember.$('head meta[name=app-user-config]').attr('content');
    // Unescape the text, then parse the resulting JSON into a real object
    userConfig = JSON.parse(unescape(userConfigEncoded));
    // Lookup the store
    store = application.lookup('service:store');
    // Push the encoded JSON into the store
    store.pushPayload(userConfig);
  }
});
Module: ember

Available since v2.14.1

keyName
String
The property key to be notified about.
returns
Ember.Observable

Convenience method to call propertyWillChange and propertyDidChange in succession.

Module: ember

Available since v2.14.1

key
String
The key to observe
target
Object
The target object to invoke
method
String|Function
The method to invoke

Remove an observer you have previously registered on this object. Pass the same key, target, and method you passed to addObserver() and your target will no longer receive notifications.

Module: ember

Available since v2.14.1

Augments a constructor's prototype with additional properties and functions:

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const MyObject = Ember.Object.extend({
  name: 'an object'
});

o = MyObject.create();
o.get('name'); // 'an object'

MyObject.reopen({
  say(msg) {
    console.log(msg);
  }
});

o2 = MyObject.create();
o2.say('hello'); // logs "hello"

o.say('goodbye'); // logs "goodbye"

To add functions and properties to the constructor itself, see reopenClass

Module: ember

Available since v2.14.1

Augments a constructor's own properties and functions:

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const MyObject = Ember.Object.extend({
  name: 'an object'
});

MyObject.reopenClass({
  canBuild: false
});

MyObject.canBuild; // false
o = MyObject.create();

In other words, this creates static properties and functions for the class. These are only available on the class and not on any instance of that class.

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const Person = Ember.Object.extend({
  name: '',
  sayHello() {
    alert(`Hello. My name is ${this.get('name')}`);
  }
});

Person.reopenClass({
  species: 'Homo sapiens',

  createPerson(name) {
    return Person.create({ name });
  }
});

let tom = Person.create({
  name: 'Tom Dale'
});
let yehuda = Person.createPerson('Yehuda Katz');

tom.sayHello(); // "Hello. My name is Tom Dale"
yehuda.sayHello(); // "Hello. My name is Yehuda Katz"
alert(Person.species); // "Homo sapiens"

Note that species and createPerson are not valid on the tom and yehuda variables. They are only valid on Person.

To add functions and properties to instances of a constructor by extending the constructor's prototype see reopen

Module: ember

Available since v2.14.1

keyName
String
The property to set
value
Object
The value to set or `null`.
returns
Object
The passed value

Sets the provided key or path to the value.

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record.set("key", value);

This method is generally very similar to calling object["key"] = value or object.key = value, except that it provides support for computed properties, the setUnknownProperty() method and property observers.

Computed Properties

If you try to set a value on a key that has a computed property handler defined (see the get() method for an example), then set() will call that method, passing both the value and key instead of simply changing the value itself. This is useful for those times when you need to implement a property that is composed of one or more member properties.

Unknown Properties

If you try to set a value on a key that is undefined in the target object, then the setUnknownProperty() handler will be called instead. This gives you an opportunity to implement complex "virtual" properties that are not predefined on the object. If setUnknownProperty() returns undefined, then set() will simply set the value on the object.

Property Observers

In addition to changing the property, set() will also register a property change with the object. Unless you have placed this call inside of a beginPropertyChanges() and endPropertyChanges(), any "local" observers (i.e. observer methods declared on the same object), will be called immediately. Any "remote" observers (i.e. observer methods declared on another object) will be placed in a queue and called at a later time in a coalesced manner.

Module: ember

Available since v2.14.1

hash
Object
the hash of keys and values to set
returns
Object
The passed in hash

Sets a list of properties at once. These properties are set inside a single beginPropertyChanges and endPropertyChanges batch, so observers will be buffered.

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record.setProperties({ firstName: 'Charles', lastName: 'Jolley' });
Module: ember

Available since v2.14.1

returns
String
string representation

Returns a string representation which attempts to provide more information than Javascript's toString typically does, in a generic way for all Ember objects.

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const Person = Ember.Object.extend()
person = Person.create()
person.toString() //=> "<Person:ember1024>"

If the object's class is not defined on an Ember namespace, it will indicate it is a subclass of the registered superclass:

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const Student = Person.extend()
let student = Student.create()
student.toString() //=> "<(subclass of Person):ember1025>"

If the method toStringExtension is defined, its return value will be included in the output.

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const Teacher = Person.extend({
  toStringExtension() {
    return this.get('fullName');
  }
});
teacher = Teacher.create()
teacher.toString(); //=> "<Teacher:ember1026:Tom Dale>"
Module: ember

Available since v2.14.1

keyName
String
The name of the property to toggle
returns
Boolean
The new property value

Set the value of a boolean property to the opposite of its current value.

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starship.toggleProperty('warpDriveEngaged');
Module: ember

Available since v2.14.1

Override to implement teardown.