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71 lines
2.9 KiB
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71 lines
2.9 KiB
Text
@ngdoc overview
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@name Developer Guide: About MVC in Angular: Understanding the Model Component
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@description
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Depending on the context of the discussion in the Angular documentation, the term _model_ can refer to
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either a single object representing one entity (for example, a model called "phones" with its value
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being an array of phones) or the entire data model for the application (all entities).
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In Angular, a model is any data that is reachable as a property of an angular {@link
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scope Scope} object. The name of the property is the model identifier and the value is
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any JavaScript object (including arrays and primitives).
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The only requirement for a JavaScript object to be a model in Angular is that the object must be
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referenced by an Angular scope as a property of that scope object. This property reference can be
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created explicitly or implicitly.
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You can create models by explicitly creating scope properties referencing JavaScript objects in the
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following ways:
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* Make a direct property assignment to the scope object in JavaScript code; this most commonly
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occurs in controllers:
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function MyCtrl($scope) {
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// create property 'foo' on the MyCtrl's scope
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// and assign it an initial value 'bar'
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$scope.foo = 'bar';
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}
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* Use an {@link expression angular expression} with an assignment operator in templates:
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<button ng-click="{{foo='ball'}}">Click me</button>
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* Use {@link api/ng.directive:ngInit ngInit directive} in templates (for toy/example apps
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only, not recommended for real applications):
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<body ng-init=" foo = 'bar' ">
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Angular creates models implicitly (by creating a scope property and assigning it a suitable value)
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when processing the following template constructs:
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* Form input, select, textarea and other form elements:
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<input ng-model="query" value="fluffy cloud">
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The code above creates a model called "query" on the current scope with the value set to "fluffy
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cloud".
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* An iterator declaration in {@link api/ng.directive:ngRepeat ngRepeater}:
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<p ng-repeat="phone in phones"></p>
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The code above creates one child scope for each item in the "phones" array and creates a "phone"
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object (model) on each of these scopes with its value set to the value of "phone" in the array.
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In Angular, a JavaScript object stops being a model when:
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* No Angular scope contains a property that references the object.
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* All Angular scopes that contain a property referencing the object become stale and eligible for
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garbage collection.
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The following illustration shows a simple data model created implicitly from a simple template:
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<img src="img/guide/about_model_final.png">
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## Related Topics
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* {@link dev_guide.mvc About MVC in Angular}
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* {@link dev_guide.mvc.understanding_controller Understanding the Controller Component}
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* {@link dev_guide.mvc.understanding_view Understanding the View Component}
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