Class Application

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.

There are two common invocation patterns for .addObserver():

• Passing two arguments:
• the name of the property to observe (as a string)
• the function to invoke (an actual function)
• Passing three arguments:
• the name of the property to observe (as a string)
• the target object (will be used to look up and invoke a function on)
• the name of the function to invoke on the target object (as a string).

import Component from '@ember/component';

export default Component.extend({
  init() {
    this._super(...arguments);

    // the following are equivalent:

    // using three arguments
    this.addObserver('foo', this, 'fooDidChange');

    // using two arguments
    this.addObserver('foo', (...args) => {
      this.fooDidChange(...args);
    });
  },

  fooDidChange() {
    // your custom logic code
  }
});

Observer Methods

Observer methods have the following signature:

import Component from '@ember/component';

export default 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.

Call advanceReadiness after any asynchronous setup logic has completed. Each call to deferReadiness must be matched by a call to advanceReadiness or the application will never become ready and routing will not begin.

Initialize the application and return a promise that resolves with the Application object when the boot process is complete.

Run any application initializers and run the application load hook. These hooks may choose to defer readiness. For example, an authentication hook might want to defer readiness until the auth token has been retrieved.

By default, this method is called automatically on "DOM ready"; however, if autoboot is disabled, this is automatically called when the first application instance is created via visit.

Create an ApplicationInstance for this application.

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.

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

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

Use this to defer readiness until some condition is true.

Example:

import Application from '@ember/application';

let App = Application.create();

App.deferReadiness();

// $ is a reference to the jQuery object/function
import $ from 'jquery;

$.getJSON('/auth-token', function(token) {
  App.token = token;
  App.advanceReadiness();
});

This allows you to perform asynchronous setup logic and defer booting your application until the setup has finished.

However, if the setup requires a loading UI, it might be better to use the router for this purpose.

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.

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:

import { computed } from '@ember/object';

fullName: 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.

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

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

is equivalent to:

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

Check if a factory is registered.

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

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

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

Example:

import EmberObject from '@ember/object';

const Person = EmberObject.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 Component from @ember/component, 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.

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.

import { debug } from '@ember/debug';

export function initialize() {
  debug('Running namedInitializer!');
}

export default {
  name: 'named-initializer',
  initialize
};

• 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:

import { debug } from '@ember/debug';

export function initialize() {
  debug('First initializer!');
}

export default {
  name: 'first',
  initialize
};

// DEBUG: First initializer!

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

import { debug } from '@ember/debug';

export function initialize() {
  debug('Second initializer!');
}

export default {
  name: 'second',
  after: 'first',
  initialize
};

// 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:

import { debug } from '@ember/debug';

export function initialize() {
  debug('Pre initializer!');
}

export default {
  name: 'pre',
  before: 'first',
  initialize
};

// 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:

import { debug } from '@ember/debug';

export function initialize() {
  debug('Post initializer!');
}

export default {
  name: 'post',
  after: ['first', 'second'],
  initialize
};

// 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:

import ApiAdapter from '../utils/api-adapter';

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

export default {
  name: 'post',
  after: ['first', 'second'],
  initialize
};

Define a dependency injection onto a specific factory or all factories of a type.

When Ember instantiates a controller, view, or other framework component it can attach a dependency to that component. This is often used to provide services to a set of framework components.

An example of providing a session object to all controllers:

import { alias } from '@ember/object/computed';
import Application from '@ember/application';
import Controller from '@ember/controller';
import EmberObject from '@ember/object';

let App = Application.create();
let Session = EmberObject.extend({ isAuthenticated: false });

// A factory must be registered before it can be injected
App.register('session:main', Session);

// Inject 'session:main' onto all factories of the type 'controller'
// with the name 'session'
App.inject('controller', 'session', 'session:main');

App.IndexController = Controller.extend({
  isLoggedIn: alias('session.isAuthenticated')
});

Injections can also be performed on specific factories.

App.inject(<full_name or type>, <property name>, <full_name>)
App.inject('route', 'source', 'source:main')
App.inject('route:application', 'email', 'model:email')

It is important to note that injections can only be performed on classes that are instantiated by Ember itself. Instantiating a class directly (via create or new) bypasses the dependency injection system.

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.

import { debug } from '@ember/debug';

export function initialize() {
  debug('Running named-instance-initializer!');
}

export default {
  name: 'named-instance-initializer',
  initialize
};

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

Example instanceInitializer to preload data into the store.

import $ from 'jquery';

export function initialize(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 = $('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);
}

export default {
  name: 'named-instance-initializer',
  initialize
};

Notify the observer system that a property has just changed.

Sometimes you need to change a value directly or indirectly without actually calling get() or set() on it. In this case, you can use this method instead. Calling this method will notify all observers that the property has potentially changed value.

Registers a factory that can be used for dependency injection (with inject) or for service lookup. Each factory is registered with a full name including two parts: type:name.

A simple example:

import Application from '@ember/application';
import EmberObject from '@ember/object';

let App = Application.create();

App.Orange = EmberObject.extend();
App.register('fruit:favorite', App.Orange);

Ember will resolve factories from the App namespace automatically. For example App.CarsController will be discovered and returned if an application requests controller:cars.

An example of registering a controller with a non-standard name:

import Application from '@ember/application';
import Controller from '@ember/controller';

let App = Application.create();
let Session = Controller.extend();

App.register('controller:session', Session);

// The Session controller can now be treated like a normal controller,
// despite its non-standard name.
App.ApplicationController = Controller.extend({
  needs: ['session']
});

Registered factories are instantiated by having create called on them. Additionally they are singletons, each time they are looked up they return the same instance.

Some examples modifying that default behavior:

import Application from '@ember/application';
import EmberObject from '@ember/object';

let App = Application.create();

App.Person = EmberObject.extend();
App.Orange = EmberObject.extend();
App.Email = EmberObject.extend();
App.session = EmberObject.create();

App.register('model:user', App.Person, { singleton: false });
App.register('fruit:favorite', App.Orange);
App.register('communication:main', App.Email, { singleton: false });
App.register('session', App.session, { instantiate: false });

Register options for a particular factory.

Allow registering options for all factories of a type.

import Application from '@ember/application';

let App = Application.create();
let appInstance = App.buildInstance();

// if all of type `connection` must not be singletons
appInstance.registerOptionsForType('connection', { singleton: false });

appInstance.register('connection:twitter', TwitterConnection);
appInstance.register('connection:facebook', FacebookConnection);

let twitter = appInstance.lookup('connection:twitter');
let twitter2 = appInstance.lookup('connection:twitter');

twitter === twitter2; // => false

let facebook = appInstance.lookup('connection:facebook');
let facebook2 = appInstance.lookup('connection:facebook');

facebook === facebook2; // => false

Return a specific registered option for a particular factory.

Return registered options for a particular factory.

Return the registered options for all factories of a type.

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.

Reset the application. This is typically used only in tests. It cleans up the application in the following order:

1. Deactivate existing routes
2. Destroy all objects in the container
3. Create a new application container
4. Re-route to the existing url

Typical Example:

import Application from '@ember/application';
let App;

run(function() {
  App = Application.create();
});

module('acceptance test', {
  setup: function() {
    App.reset();
  }
});

test('first test', function() {
  // App is freshly reset
});

test('second test', function() {
  // App is again freshly reset
});

Advanced Example:

Occasionally you may want to prevent the app from initializing during setup. This could enable extra configuration, or enable asserting prior to the app becoming ready.

import Application from '@ember/application';
let App;

run(function() {
  App = Application.create();
});

module('acceptance test', {
  setup: function() {
    run(function() {
      App.reset();
      App.deferReadiness();
    });
  }
});

test('first test', function() {
  ok(true, 'something before app is initialized');

  run(function() {
    App.advanceReadiness();
  });

  ok(true, 'something after app is initialized');
});

Given a fullName return the corresponding factory.

Sets the provided key or path to the value.

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.

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

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

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

import EmberObject from '@ember/object';

const Person = EmberObject.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:

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.

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

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

starship.toggleProperty('warpDriveEngaged');

Unregister a factory.

import Application from '@ember/application';
import EmberObject from '@ember/object';

let App = Application.create();
let User = EmberObject.extend();
App.register('model:user', User);

App.resolveRegistration('model:user').create() instanceof User //=> true

App.unregister('model:user')
App.resolveRegistration('model:user') === undefined //=> true

Boot a new instance of ApplicationInstance for the current application and navigate it to the given url. Returns a Promise that resolves with the instance when the initial routing and rendering is complete, or rejects with any error that occurred during the boot process.

When autoboot is disabled, calling visit would first cause the application to boot, which runs the application initializers.

This method also takes a hash of boot-time configuration options for customizing the instance's behavior. See the documentation on ApplicationInstance.BootOptions for details.

ApplicationInstance.BootOptions is an interface class that exists purely to document the available options; you do not need to construct it manually. Simply pass a regular JavaScript object containing of the desired options:

MyApp.visit("/", { location: "none", rootElement: "#container" });

Supported Scenarios

While the BootOptions class exposes a large number of knobs, not all combinations of them are valid; certain incompatible combinations might result in unexpected behavior.

For example, booting the instance in the full browser environment while specifying a foreign document object (e.g. { isBrowser: true, document: iframe.contentDocument }) does not work correctly today, largely due to Ember's jQuery dependency.

Currently, there are three officially supported scenarios/configurations. Usages outside of these scenarios are not guaranteed to work, but please feel free to file bug reports documenting your experience and any issues you encountered to help expand support.

Browser Applications (Manual Boot)

The setup is largely similar to how Ember works out-of-the-box. Normally, Ember will boot a default instance for your Application on "DOM ready". However, you can customize this behavior by disabling autoboot.

For example, this allows you to render a miniture demo of your application into a specific area on your marketing website:

import MyApp from 'my-app';

$(function() {
  let App = MyApp.create({ autoboot: false });

  let options = {
    // Override the router's location adapter to prevent it from updating
    // the URL in the address bar
    location: 'none',

    // Override the default `rootElement` on the app to render into a
    // specific `div` on the page
    rootElement: '#demo'
  };

  // Start the app at the special demo URL
  App.visit('/demo', options);
});

Or perhaps you might want to boot two instances of your app on the same page for a split-screen multiplayer experience:

import MyApp from 'my-app';

$(function() {
  let App = MyApp.create({ autoboot: false });

  let sessionId = MyApp.generateSessionID();

  let player1 = App.visit(`/matches/join?name=Player+1&session=${sessionId}`, { rootElement: '#left', location: 'none' });
  let player2 = App.visit(`/matches/join?name=Player+2&session=${sessionId}`, { rootElement: '#right', location: 'none' });

  Promise.all([player1, player2]).then(() => {
    // Both apps have completed the initial render
    $('#loading').fadeOut();
  });
});

Do note that each app instance maintains their own registry/container, so they will run in complete isolation by default.

Server-Side Rendering (also known as FastBoot)

This setup allows you to run your Ember app in a server environment using Node.js and render its content into static HTML for SEO purposes.

const HTMLSerializer = new SimpleDOM.HTMLSerializer(SimpleDOM.voidMap);

function renderURL(url) {
  let dom = new SimpleDOM.Document();
  let rootElement = dom.body;
  let options = { isBrowser: false, document: dom, rootElement: rootElement };

  return MyApp.visit(options).then(instance => {
    try {
      return HTMLSerializer.serialize(rootElement.firstChild);
    } finally {
      instance.destroy();
    }
  });
}

In this scenario, because Ember does not have access to a global document object in the Node.js environment, you must provide one explicitly. In practice, in the non-browser environment, the stand-in document object only needs to implement a limited subset of the full DOM API. The SimpleDOM library is known to work.

Since there is no access to jQuery in the non-browser environment, you must also specify a DOM Element object in the same document for the rootElement option (as opposed to a selector string like "body").

See the documentation on the isBrowser, document and rootElement properties on ApplicationInstance.BootOptions for details.

Server-Side Resource Discovery

This setup allows you to run the routing layer of your Ember app in a server environment using Node.js and completely disable rendering. This allows you to simulate and discover the resources (i.e. AJAX requests) needed to fulfill a given request and eagerly "push" these resources to the client.

import BrowserNetworkService from 'app/services/network/browser';
import NodeNetworkService from 'app/services/network/node';

// Inject a (hypothetical) service for abstracting all AJAX calls and use
// the appropriate implementation on the client/server. This also allows the
// server to log all the AJAX calls made during a particular request and use
// that for resource-discovery purpose.

export function initialize(application) {
  if (window) { // browser
    application.register('service:network', BrowserNetworkService);
  } else { // node
    application.register('service:network', NodeNetworkService);
  }

  application.inject('route', 'network', 'service:network');
};

export default {
  name: 'network-service',
  initialize: initialize
};

import Route from '@ember/routing/route';

// An example of how the (hypothetical) service is used in routes.

export default Route.extend({
  model(params) {
    return this.network.fetch(`/api/posts/${params.post_id}.json`);
  },

  afterModel(post) {
    if (post.isExternalContent) {
      return this.network.fetch(`/api/external/?url=${post.externalURL}`);
    } else {
      return post;
    }
  }
});

// Finally, put all the pieces together

function discoverResourcesFor(url) {
  return MyApp.visit(url, { isBrowser: false, shouldRender: false }).then(instance => {
    let networkService = instance.lookup('service:network');
    return networkService.requests; // => { "/api/posts/123.json": "..." }
  });
}

Override to implement teardown.