Ember.Engine Class
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()
.
Item Index
Methods
- _lazyInjections
- _onLookup
- _scheduledDestroy
- addObserver
- beginPropertyChanges
- buildInstance
- buildRegistry
- buildRegistry static
- cacheFor
- decrementProperty
- destroy
- endPropertyChanges
- ensureInitializers
- get
- getProperties
- getWithDefault
- hasObserverFor
- incrementProperty
- init
- initializer
- initializer
- instanceInitializer
- instanceInitializer
- notifyPropertyChange
- propertyDidChange
- propertyWillChange
- removeObserver
- reopen
- reopenClass
- resolverFor
- runInitializers
- runInstanceInitializers
- set
- setProperties
- toggleProperty
- toString
- willDestroy
Properties
Methods
_lazyInjections
()
Object
private
Returns:
_onLookup
()
private
_scheduledDestroy
()
private
destroy
method.
addObserver
-
key
-
target
-
method
context
parameter:
`
javascript
fooDidChange: function(sender, key, value, rev) { };
`
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.
If you pass a context
parameter, the context will be passed before the
revision like so:
`
javascript
fooDidChange: function(sender, key, value, context, rev) { };
`
Usually you will not need the value, context 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.
beginPropertyChanges
()
Ember.Observable
private
endPropertyChanges()
to deliver the deferred change notifications and end
deferring.
Returns:
buildInstance
()
Ember.EngineInstance
private
Create an EngineInstance for this engine.
Returns:
the engine instance
buildRegistry
()
Ember.Registry
private
Build and configure the registry for the current engine.
Returns:
the configured registry
buildRegistry
-
namespace
This creates a registry with the default Ember naming conventions.
It also configures the registry:
- registered views are created every time they are looked up (they are not singletons)
- registered templates are not factories; the registered value is returned directly.
- the router receives the application as its
namespace
property - all controllers receive the router as their
target
andcontrollers
properties - all controllers receive the application as their
namespace
property - the application view receives the application controller as its
controller
property - the application view receives the application template as its
defaultTemplate
property
Parameters:
-
namespace
Ember.Applicationthe application for which to build the registry
Returns:
the built registry
cacheFor
-
keyName
Parameters:
-
keyName
String
Returns:
decrementProperty
-
keyName
-
decrement
`
javascript
player.decrementProperty('lives');
orc.decrementProperty('health', 5);
`
Parameters:
-
keyName
StringThe name of the property to decrement -
decrement
NumberThe amount to decrement by. Defaults to 1
Returns:
destroy
()
Ember.Object
public
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.
Returns:
endPropertyChanges
()
Ember.Observable
private
beginPropertyChanges()
at the beginning of the changes to defer change
notifications. When you are done making changes, call this method to
deliver the deferred change notifications and end deferring.
Returns:
ensureInitializers
()
private
Ensure that initializers are run once, and only once, per engine.
get
-
keyName
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:
`
javascript
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.
Parameters:
-
keyName
StringThe property to retrieve
Returns:
getProperties
-
list
getProperties
with a list of strings or an array:
`
javascript
record.getProperties('firstName', 'lastName', 'zipCode');
// { firstName: 'John', lastName: 'Doe', zipCode: '10011' }
`
is equivalent to:
`
javascript
record.getProperties(['firstName', 'lastName', 'zipCode']);
// { firstName: 'John', lastName: 'Doe', zipCode: '10011' }
`
Parameters:
-
list
String... | Arrayof keys to get
Returns:
getWithDefault
-
keyName
-
defaultValue
undefined
.
`
javascript
person.getWithDefault('lastName', 'Doe');
`
Parameters:
-
keyName
StringThe name of the property to retrieve -
defaultValue
ObjectThe value to return if the property value is undefined
Returns:
hasObserverFor
-
key
true
if the object currently has observers registered for a
particular key. You can use this method to potentially defer performing
an expensive action until someone begins observing a particular property
on the object.
Parameters:
-
key
StringKey to check
Returns:
incrementProperty
-
keyName
-
increment
`
javascript
person.incrementProperty('age');
team.incrementProperty('score', 2);
`
Parameters:
-
keyName
StringThe name of the property to increment -
increment
NumberThe amount to increment by. Defaults to 1
Returns:
init
()
public
`
javascript
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.
initializer
-
initializer
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.
Ember.Application.initializer({
name: 'namedInitializer',
initialize: function(application) {
Ember.debug('Running namedInitializer!');
}
});
before
andafter
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 thename
of other initializers.
An example of ordering initializers, we create an initializer named first
:
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
:
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
:
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:
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:
Ember.Application.initializer({
name: 'api-adapter',
initialize: function(application) {
application.register('api-adapter:main', ApiAdapter);
}
});
Parameters:
-
initializer
Object
initializer
()
private
instanceInitializer
-
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.
Ember.Application.instanceInitializer({
name: 'namedinstanceInitializer',
initialize: function(application) {
Ember.debug('Running namedInitializer!');
}
});
-
before
andafter
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 thename
of other initializers. -
See Ember.Application.initializer for discussion on the usage of before and after.
Example instanceInitializer to preload data into the store.
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);
}
});
Parameters:
-
instanceInitializer
Object
instanceInitializer
()
private
notifyPropertyChange
-
keyName
propertyWillChange
and propertyDidChange
in
succession.
Parameters:
-
keyName
StringThe property key to be notified about.
Returns:
propertyDidChange
-
keyName
get()
or set()
on it. In this case, you can use this
method and propertyWillChange()
instead. Calling these two methods
together will notify all observers that the property has potentially
changed value.
Note that you must always call propertyWillChange
and propertyDidChange
as a pair. If you do not, it may get the property change groups out of
order and cause notifications to be delivered more often than you would
like.
Parameters:
-
keyName
StringThe property key that has just changed.
Returns:
propertyWillChange
-
keyName
get()
or set()
on it. In this case, you can use this
method and propertyDidChange()
instead. Calling these two methods
together will notify all observers that the property has potentially
changed value.
Note that you must always call propertyWillChange
and propertyDidChange
as a pair. If you do not, it may get the property change groups out of
order and cause notifications to be delivered more often than you would
like.
Parameters:
-
keyName
StringThe property key that is about to change.
Returns:
removeObserver
-
key
-
target
-
method
addObserver()
and your
target will no longer receive notifications.
reopen
()
public
`
javascript
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
reopenClass
()
public
`
javascript
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.
`
javascript
const Person = Ember.Object.extend({
name: "",
sayHello() {
alert("Hello. My name is " + this.get('name'));
}
});
Person.reopenClass({
species: "Homo sapiens",
createPerson(newPersonsName){
return Person.create({
name:newPersonsName
});
}
});
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
resolverFor
-
namespace
This function defines the default lookup rules for container lookups:
- templates are looked up on
Ember.TEMPLATES
- other names are looked up on the application after classifying the name.
For example,
controller:post
looks upApp.PostController
by default. - if the default lookup fails, look for registered classes on the container
This allows the application to register default injections in the container that could be overridden by the normal naming convention.
Parameters:
-
namespace
Ember.Namespacethe namespace to look for classes
Returns:
the resolved value for a given lookup
runInitializers
()
private
runInstanceInitializers
()
private
set
-
keyName
-
value
`
javascript
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.
Parameters:
-
keyName
StringThe property to set -
value
ObjectThe value to set ornull
.
Returns:
setProperties
-
hash
beginPropertyChanges
and endPropertyChanges
batch, so
observers will be buffered.
`
javascript
record.setProperties({ firstName: 'Charles', lastName: 'Jolley' });
`
Parameters:
-
hash
Objectthe hash of keys and values to set
Returns:
toggleProperty
-
keyName
`
javascript
starship.toggleProperty('warpDriveEngaged');
`
Parameters:
-
keyName
StringThe name of the property to toggle
Returns:
toString
()
String
public
toString
typically does, in a generic way for all Ember
objects.
`
javascript
const Person = Ember.Object.extend()
person = Person.create()
person.toString() //=> "`
If the object's class is not defined on an Ember namespace, it will
indicate it is a subclass of the registered superclass:
`
javascript
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.
`
javascript
const Teacher = Person.extend({
toStringExtension() {
return this.get('fullName');
}
});
teacher = Teacher.create()
teacher.toString(); //=> "`
Returns:
willDestroy
()
public
Properties
_initializersRan
Unknown
private
A private flag indicating whether an engine's initializers have run yet.
concatenatedProperties
Array
public
classNames
property of Ember.View
.
Here is some sample code showing the difference between a concatenated
property and a normal one:
`
javascript
const Bar = Ember.Object.extend({
// Configure which properties to concatenate
concatenatedProperties: ['concatenatedProperty'],
someNonConcatenatedProperty: ['bar'],
concatenatedProperty: ['bar']
});
const FooBar = Bar.extend({
someNonConcatenatedProperty: ['foo'],
concatenatedProperty: ['foo']
});
let fooBar = FooBar.create();
fooBar.get('someNonConcatenatedProperty'); // ['foo']
fooBar.get('concatenatedProperty'); // ['bar', 'foo']
`
This behavior extends to object creation as well. Continuing the
above example:
`
javascript
let fooBar = FooBar.create({
someNonConcatenatedProperty: ['baz'],
concatenatedProperty: ['baz']
})
fooBar.get('someNonConcatenatedProperty'); // ['baz']
fooBar.get('concatenatedProperty'); // ['bar', 'foo', 'baz']
`
Adding a single property that is not an array will just add it in the array:
`
javascript
let fooBar = FooBar.create({
concatenatedProperty: 'baz'
})
view.get('concatenatedProperty'); // ['bar', 'foo', 'baz']
`
Using the concatenatedProperties
property, we can tell Ember to mix the
content of the properties.
In Ember.Component
the classNames
, classNameBindings
and
attributeBindings
properties are concatenated.
This feature is available for you to use throughout the Ember object model,
although typical app developers are likely to use it infrequently. Since
it changes expectations about behavior of properties, you should properly
document its usage in each individual concatenated property (to not
mislead your users to think they can override the property in a subclass).
Default: null
isDestroyed
Unknown
public
true
the observers and bindings were already
removed by the effect of calling the destroy()
method.
Default: false
isDestroying
Unknown
public
destroy()
method has been called.
The object stays intact until the end of the run loop at which point
the isDestroyed
flag is set.
Default: false
mergedProperties
Array
public
queryParams
property of routes.
Here is some sample code showing the difference between a merged
property and a normal one:
`
javascript
const Bar = Ember.Object.extend({
// Configure which properties are to be merged
mergedProperties: ['mergedProperty'],
someNonMergedProperty: {
nonMerged: 'superclass value of nonMerged'
},
mergedProperty: {
page: {replace: false},
limit: {replace: true}
}
});
const FooBar = Bar.extend({
someNonMergedProperty: {
completelyNonMerged: 'subclass value of nonMerged'
},
mergedProperty: {
limit: {replace: false}
}
});
let fooBar = FooBar.create();
fooBar.get('someNonMergedProperty');
// => { completelyNonMerged: 'subclass value of nonMerged' }
//
// Note the entire object, including the nonMerged property of
// the superclass object, has been replaced
fooBar.get('mergedProperty');
// => {
// page: {replace: false},
// limit: {replace: false}
// }
//
// Note the page remains from the superclass, and the
// limit
property's value of false
has been merged from
// the subclass.
`
This behavior is not available during object create
calls. It is only
available at extend
time.
In Ember.Route
the queryParams
property is merged.
This feature is available for you to use throughout the Ember object model,
although typical app developers are likely to use it infrequently. Since
it changes expectations about behavior of properties, you should properly
document its usage in each individual merged property (to not
mislead your users to think they can override the property in a subclass).
Default: null
resolver
Unknown
deprecated
public
Set this to provide an alternate class to Ember.DefaultResolver
resolver
Unknown
public
Set this to provide an alternate class to Ember.DefaultResolver