Ember._SimpleMetamorphView Class
Item Index
Methods
- _scheduledDestroy
- addObserver
- beginPropertyChanges
- cacheFor
- decrementProperty
- destroy
- eachComputedProperty
- endPropertyChanges
- get
- getProperties
- getWithDefault
- has
- hasObserverFor
- incrementProperty
- init
- metaForProperty
- notifyPropertyChange
- off
- on
- one
- propertyDidChange
- propertyWillChange
- removeObserver
- renderToBuffer
- reopen
- reopenClass
- send
- set
- setProperties
- toggleProperty
- toString
- trigger
- willDestroy
- willMergeMixin
Methods
_scheduledDestroy
()
private
Invoked by the run loop to actually destroy the object. This is
scheduled for execution by the
destroy method.
addObserver
(
-
key -
target -
method
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.
You can also pass an optional context parameter to this method. The
context will be passed to your observer method whenever it is triggered.
Note that if you add the same target/method pair on a key multiple times
with different context parameters, your observer will only be called once
with the last context you passed.
### Observer Methods
Observer methods you pass should generally have the following signature if
you do not pass a
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
Begins a grouping of property changes.
You can use this method to group property changes so that notifications
will not be sent until the changes are finished. If you plan to make a
large number of changes to an object at one time, you should call this
method at the beginning of the changes to begin deferring change
notifications. When you are done making changes, call
endPropertyChanges() to deliver the deferred change notifications and end
deferring.
Returns:
cacheFor
(
Object
-
keyName
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.
Parameters:
-
keyNameString
Returns:
Object:
The cached value of the computed property, if any
decrementProperty
(
Number
-
keyName -
decrement
Set the value of a property to the current value minus some amount.
`javascript
player.decrementProperty('lives');
orc.decrementProperty('health', 5);
`
Parameters:
-
keyNameStringThe name of the property to decrement -
decrementNumberThe amount to decrement by. Defaults to 1
Returns:
Number:
The new property value
destroy
()
Ember.Object
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.
Returns:
Ember.Object:
receiver
eachComputedProperty
(
-
callback -
binding
Iterate over each computed property for the class, passing its name
and any associated metadata (see
metaForProperty) to the callback.
Parameters:
-
callbackFunction -
bindingObject
endPropertyChanges
()
Ember.Observable
Ends a grouping of property changes.
You can use this method to group property changes so that notifications
will not be sent until the changes are finished. If you plan to make a
large number of changes to an object at one time, you should call
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:
get
(
Object
-
keyName
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:
`javascript
fullName: function() {
return this.get('firstName') + ' ' + this.get('lastName');
}.property('firstName', '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:
-
keyNameStringThe property to retrieve
Returns:
Object:
The property value or undefined.
getProperties
(
Hash
-
list
To get multiple properties at once, call
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:
-
listString... | Arrayof keys to get
Returns:
Hash:
getWithDefault
(
Object
-
keyName -
defaultValue
Retrieves the value of a property, or a default value in the case that the
property returns
undefined.
`javascript
person.getWithDefault('lastName', 'Doe');
`
Parameters:
-
keyNameStringThe name of the property to retrieve -
defaultValueObjectThe value to return if the property value is undefined
Returns:
Object:
The property value or the defaultValue.
has
(
Boolean
-
name
Checks to see if object has any subscriptions for named event.
Parameters:
-
nameStringThe name of the event
Returns:
Boolean:
does the object have a subscription for event
hasObserverFor
(
Boolean
-
key
Returns
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:
-
keyStringKey to check
Returns:
Boolean:
incrementProperty
(
Number
-
keyName -
increment
Set the value of a property to the current value plus some amount.
`javascript
person.incrementProperty('age');
team.incrementProperty('score', 2);
`
Parameters:
-
keyNameStringThe name of the property to increment -
incrementNumberThe amount to increment by. Defaults to 1
Returns:
Number:
The new property value
init
()
An overridable method called when objects are instantiated. By default,
does nothing unless it is overridden during class definition.
Example:
`javascript
App.Person = Ember.Object.extend({
init: function() {
alert('Name is ' + this.get('name'));
}
});
var steve = App.Person.create({
name: "Steve"
});
// alerts 'Name is Steve'.
`
NOTE: If you do override init for a framework class like Ember.View or
Ember.ArrayController, be sure to call this._super() 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.
metaForProperty
(
-
key
In some cases, you may want to annotate computed properties with additional
metadata about how they function or what values they operate on. For
example, computed property functions may close over variables that are then
no longer available for introspection.
You can pass a hash of these values to a computed property like this:
`javascript
person: function() {
var personId = this.get('personId');
return App.Person.create({ id: personId });
}.property().meta({ type: App.Person })
`
Once you've done this, you can retrieve the values saved to the computed
property from your class like this:
`javascript
MyClass.metaForProperty('person');
`
This will return the original hash that was passed to meta().
Parameters:
-
keyStringproperty name
notifyPropertyChange
(
Ember.Observable
-
keyName
Convenience method to call
propertyWillChange and propertyDidChange in
succession.
Parameters:
-
keyNameStringThe property key to be notified about.
Returns:
off
(
-
name -
target -
method
Cancels subscription for given name, target, and method.
Parameters:
Returns:
this
on
(
-
name -
[target] -
method
Subscribes to a named event with given function.
`javascript
person.on('didLoad', function() {
// fired once the person has loaded
});
`
An optional target can be passed in as the 2nd argument that will
be set as the "this" for the callback. This is a good way to give your
function access to the object triggering the event. When the target
parameter is used the callback becomes the third argument.
Parameters:
Returns:
this
one
(
-
name -
[target] -
method
Subscribes a function to a named event and then cancels the subscription
after the first time the event is triggered. It is good to use
`one` when
you only care about the first time an event has taken place.
This function takes an optional 2nd argument that will become the "this"
value for the callback. If this argument is passed then the 3rd argument
becomes the function.
Parameters:
Returns:
this
propertyDidChange
(
Ember.Observable
-
keyName
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 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:
-
keyNameStringThe property key that has just changed.
Returns:
propertyWillChange
(
Ember.Observable
-
keyName
Notify the observer system that a property is about to change.
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 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:
-
keyNameStringThe property key that is about to change.
Returns:
removeObserver
(
-
key -
target -
method
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.
renderToBuffer
(
private
-
buffer
Invoked by the view system when this view needs to produce an HTML
representation. This method will create a new render buffer, if needed,
then apply any default attributes, such as class names and visibility.
Finally, the
render() method is invoked, which is responsible for
doing the bulk of the rendering.
You should not need to override this method; instead, implement the
template property, or if you need more control, override the render
method.
Parameters:
-
bufferEmber.RenderBufferthe render buffer. If no buffer is passed, a default buffer, using the current view'stagName, will be used.
reopen
()
Augments a constructor's prototype with additional
properties and functions:
`javascript
MyObject = Ember.Object.extend({
name: 'an object'
});
o = MyObject.create();
o.get('name'); // 'an object'
MyObject.reopen({
say: function(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
()
Augments a constructor's own properties and functions:
`javascript
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
App.Person = Ember.Object.extend({
name : "",
sayHello : function(){
alert("Hello. My name is " + this.get('name'));
}
});
App.Person.reopenClass({
species : "Homo sapiens",
createPerson: function(newPersonsName){
return App.Person.create({
name:newPersonsName
});
}
});
var tom = App.Person.create({
name : "Tom Dale"
});
var yehuda = App.Person.createPerson("Yehuda Katz");
tom.sayHello(); // "Hello. My name is Tom Dale"
yehuda.sayHello(); // "Hello. My name is Yehuda Katz"
alert(App.Person.species); // "Homo sapiens"
`
Note that species and createPerson are *not* valid on the tom and yehuda
variables. They are only valid on App.Person.
To add functions and properties to instances of
a constructor by extending the constructor's prototype
see reopen
send
(
-
actionName -
context
Triggers a named action on the
ActionHandler. Any parameters
supplied after the actionName string will be passed as arguments
to the action target function.
If the ActionHandler has its target property set, actions may
bubble to the target. Bubbling happens when an actionName can
not be found in the ActionHandler's actions hash or if the
action target function returns true.
Example
`js
App.WelcomeRoute = Ember.Route.extend({
actions: {
playTheme: function() {
this.send('playMusic', 'theme.mp3');
},
playMusic: function(track) {
// ...
}
}
});
`
Parameters:
-
actionNameStringThe action to trigger -
contexta context to send with the action
set
(
Ember.Observable
-
keyName -
value
Sets the provided key or path to the 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.
### Chaining
In addition to property changes, set() returns the value of the object
itself so you can do chaining like this:
`javascript
record.set('firstName', 'Charles').set('lastName', 'Jolley');
`
Parameters:
-
keyNameStringThe property to set -
valueObjectThe value to set ornull.
Returns:
setProperties
(
Ember.Observable
-
hash
Sets a list of properties at once. These properties are set inside
a single
beginPropertyChanges and endPropertyChanges batch, so
observers will be buffered.
`javascript
record.setProperties({ firstName: 'Charles', lastName: 'Jolley' });
`
Parameters:
-
hashHashthe hash of keys and values to set
Returns:
toggleProperty
(
Object
-
keyName
Set the value of a boolean property to the opposite of it's
current value.
`javascript
starship.toggleProperty('warpDriveEngaged');
`
Parameters:
-
keyNameStringThe name of the property to toggle
Returns:
Object:
The new property value
toString
()
String
Returns a string representation which attempts to provide more information
than Javascript's "
"
toString typically does, in a generic way for all Ember
objects.
`javascript
App.Person = Em.Object.extend()
person = App.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
Student = App.Person.extend()
student = Student.create()
student.toString() //=> "<(subclass of App.Person):ember1025>"
`
If the method toStringExtension is defined, its return value will be
included in the output.
`javascript
App.Teacher = App.Person.extend({
toStringExtension: function() {
return this.get('fullName');
}
});
teacher = App.Teacher.create()
teacher.toString(); //=> "`
Returns:
String:
string representation
trigger
(
private
-
name
Override the default event firing from
Ember.Evented to
also call methods with the given name.
Parameters:
-
nameString
willDestroy
()
Override to implement teardown.
willMergeMixin
()
private
Moves
actions to _actions at extend time. Note that this currently
modifies the mixin themselves, which is technically dubious but
is practically of little consequence. This may change in the future.
Properties
actions
Hash
The collection of functions, keyed by name, available on this
ActionHandler as action targets.
These functions will be invoked when a matching {{action}} is triggered
from within a template and the application's current route is this route.
Actions can also be invoked from other parts of your application
via ActionHandler#send.
The actions hash will inherit action handlers from
the actions hash defined on extended parent classes
or mixins rather than just replace the entire hash, e.g.:
`js
App.CanDisplayBanner = Ember.Mixin.create({
actions: {
displayBanner: function(msg) {
// ...
}
}
});
App.WelcomeRoute = Ember.Route.extend(App.CanDisplayBanner, {
actions: {
playMusic: function() {
// ...
}
}
});
// WelcomeRoute, when active, will be able to respond
// to both actions, since the actions hash is merged rather
// then replaced when extending mixins / parent classes.
this.send('displayBanner');
this.send('playMusic');
`
Within a Controller, Route, View or Component's action handler,
the value of the this context is the Controller, Route, View or
Component object:
`js
App.SongRoute = Ember.Route.extend({
actions: {
myAction: function() {
this.controllerFor("song");
this.transitionTo("other.route");
...
}
}
});
`
It is also possible to call this._super() from within an
action handler if it overrides a handler defined on a parent
class or mixin:
Take for example the following routes:
`js
App.DebugRoute = Ember.Mixin.create({
actions: {
debugRouteInformation: function() {
console.debug("trololo");
}
}
});
App.AnnoyingDebugRoute = Ember.Route.extend(App.DebugRoute, {
actions: {
debugRouteInformation: function() {
// also call the debugRouteInformation of mixed in App.DebugRoute
this._super();
// show additional annoyance
window.alert(...);
}
}
});
`
## Bubbling
By default, an action will stop bubbling once a handler defined
on the actions hash handles it. To continue bubbling the action,
you must return true from the handler:
`js
App.Router.map(function() {
this.resource("album", function() {
this.route("song");
});
});
App.AlbumRoute = Ember.Route.extend({
actions: {
startPlaying: function() {
}
}
});
App.AlbumSongRoute = Ember.Route.extend({
actions: {
startPlaying: function() {
// ...
if (actionShouldAlsoBeTriggeredOnParentRoute) {
return true;
}
}
}
});
`
Default: null
concatenatedProperties
Array
Defines the properties that will be concatenated from the superclass
(instead of overridden).
By default, when you extend an Ember class a property defined in
the subclass overrides a property with the same name that is defined
in the superclass. However, there are some cases where it is preferable
to build up a property's value by combining the superclass' property
value with the subclass' value. An example of this in use within Ember
is the
classNames property of Ember.View.
Here is some sample code showing the difference between a concatenated
property and a normal one:
`javascript
App.BarView = Ember.View.extend({
someNonConcatenatedProperty: ['bar'],
classNames: ['bar']
});
App.FooBarView = App.BarView.extend({
someNonConcatenatedProperty: ['foo'],
classNames: ['foo'],
});
var fooBarView = App.FooBarView.create();
fooBarView.get('someNonConcatenatedProperty'); // ['foo']
fooBarView.get('classNames'); // ['ember-view', 'bar', 'foo']
`
This behavior extends to object creation as well. Continuing the
above example:
`javascript
var view = App.FooBarView.create({
someNonConcatenatedProperty: ['baz'],
classNames: ['baz']
})
view.get('someNonConcatenatedProperty'); // ['baz']
view.get('classNames'); // ['ember-view', 'bar', 'foo', 'baz']
`
Adding a single property that is not an array will just add it in the array:
`javascript
var view = App.FooBarView.create({
classNames: 'baz'
})
view.get('classNames'); // ['ember-view', 'bar', 'foo', 'baz']
`
Using the concatenatedProperties property, we can tell to Ember that mix
the content of the properties.
In Ember.View the classNameBindings and attributeBindings properties
are also concatenated, in addition to classNames.
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
Destroyed object property flag.
if this property is
true the observers and bindings were already
removed by the effect of calling the destroy() method.
Default: false
isDestroying
Unknown
Destruction scheduled flag. The
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
parentView
Ember.View
If the view is currently inserted into the DOM of a parent view, this
property will point to the parent of the view.
Default: null