Ember.Service Class
Item Index
Methods
- _lazyInjections
- _onLookup
- _scheduledDestroy
- addObserver
- beginPropertyChanges
- cacheFor
- decrementProperty
- destroy
- endPropertyChanges
- get
- getProperties
- getWithDefault
- hasObserverFor
- incrementProperty
- init
- notifyPropertyChange
- propertyDidChange
- propertyWillChange
- removeObserver
- reopen
- reopenClass
- set
- setProperties
- toggleProperty
- toString
- willDestroy
Methods
_lazyInjections
()
Object
private
Returns a hash of property names and container names that injected properties will lookup on the container lazily.
Returns:
Hash of all lazy injected property keys to container names
_onLookup
()
private
Provides lookup-time type validation for injected properties.
_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:
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:
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
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
-
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:
-
keyName
String
Returns:
The cached value of the computed property, if any
decrementProperty
-
keyName
-
decrement
Set the value of a property to the current value minus some amount.
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:
The new property value
destroy
()
Ember.Object
public
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:
receiver
endPropertyChanges
()
Ember.Observable
private
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
-
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:
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:
The property value or undefined.
getProperties
-
list
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' }
Parameters:
-
list
String... | Arrayof keys to get
Returns:
getWithDefault
-
keyName
-
defaultValue
Retrieves the value of a property, or a default value in the case that the
property returns undefined
.
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:
The property value or the defaultValue.
hasObserverFor
-
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:
-
key
StringKey to check
Returns:
incrementProperty
-
keyName
-
increment
Set the value of a property to the current value plus some amount.
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:
The new property value
init
()
public
An overridable method called when objects are instantiated. By default, does nothing unless it is overridden during class definition.
Example:
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.
notifyPropertyChange
-
keyName
Convenience method to call propertyWillChange
and propertyDidChange
in
succession.
Parameters:
-
keyName
StringThe property key to be notified about.
Returns:
propertyDidChange
-
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:
-
keyName
StringThe property key that has just changed.
Returns:
propertyWillChange
-
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:
-
keyName
StringThe 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.
reopen
()
public
Augments a constructor's prototype with additional properties and functions:
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
Augments a constructor's own properties and functions:
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.
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
set
-
keyName
-
value
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.
Parameters:
-
keyName
StringThe property to set
-
value
ObjectThe value to set or
null
.
Returns:
The passed value
setProperties
-
hash
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' });
Parameters:
-
hash
Objectthe hash of keys and values to set
Returns:
The passed in hash
toggleProperty
-
keyName
Set the value of a boolean property to the opposite of its current value.
starship.toggleProperty('warpDriveEngaged');
Parameters:
-
keyName
StringThe name of the property to toggle
Returns:
The new property value
toString
()
String
public
Returns a string representation which attempts to provide more information
than Javascript's toString
typically does, in a generic way for all Ember
objects.
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:
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>"
Returns:
string representation
willDestroy
()
public
Override to implement teardown.
Properties
concatenatedProperties
Array
public
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:
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:
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:
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
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
public
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
mergedProperties
Array
public
Defines the properties that will be merged 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 merging the superclass property value
with the subclass property's value. An example of this in use within Ember
is the queryParams
property of routes.
Here is some sample code showing the difference between a merged property and a normal one:
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