diff --git a/modules/angular2/src/core/metadata.ts b/modules/angular2/src/core/metadata.ts index 9458f62c52..dae5f067cd 100644 --- a/modules/angular2/src/core/metadata.ts +++ b/modules/angular2/src/core/metadata.ts @@ -505,82 +505,915 @@ export interface HostListenerFactory { new (eventName: string, args?: string[]): any; } +// TODO(alexeagle): remove the duplication of this doc. It is copied from ComponentMetadata. /** - * {@link ComponentMetadata} factory function. + * Declare reusable UI building blocks for an application. + * + * Each Angular component requires a single `@Component` and at least one `@View` annotation. The + * `@Component` + * annotation specifies when a component is instantiated, and which properties and hostListeners it + * binds to. + * + * When a component is instantiated, Angular + * - creates a shadow DOM for the component. + * - loads the selected template into the shadow DOM. + * - creates all the injectable objects configured with `providers` and `viewProviders`. + * + * All template expressions and statements are then evaluated against the component instance. + * + * For details on the `@View` annotation, see {@link ViewMetadata}. + * + * ## Lifecycle hooks + * + * When the component class implements some {@link angular2/lifecycle_hooks} the callbacks are + * called by the change detection at defined points in time during the life of the component. + * + * ## Example + * + * ``` + * @Component({ + * selector: 'greet', + * template: 'Hello {{name}}!' + * }) + * class Greet { + * name: string; + * + * constructor() { + * this.name = 'World'; + * } + * } + * ``` + * */ export var Component: ComponentFactory = makeDecorator(ComponentMetadata, (fn: any) => fn.View = View); + +// TODO(alexeagle): remove the duplication of this doc. It is copied from DirectiveMetadata. /** - * {@link DirectiveMetadata} factory function. + * Directives allow you to attach behavior to elements in the DOM. + * + * {@link DirectiveMetadata}s with an embedded view are called {@link ComponentMetadata}s. + * + * A directive consists of a single directive annotation and a controller class. When the + * directive's `selector` matches + * elements in the DOM, the following steps occur: + * + * 1. For each directive, the `ElementInjector` attempts to resolve the directive's constructor + * arguments. + * 2. Angular instantiates directives for each matched element using `ElementInjector` in a + * depth-first order, + * as declared in the HTML. + * + * ## Understanding How Injection Works + * + * There are three stages of injection resolution. + * - *Pre-existing Injectors*: + * - The terminal {@link Injector} cannot resolve dependencies. It either throws an error or, if + * the dependency was + * specified as `@Optional`, returns `null`. + * - The platform injector resolves browser singleton resources, such as: cookies, title, + * location, and others. + * - *Component Injectors*: Each component instance has its own {@link Injector}, and they follow + * the same parent-child hierarchy + * as the component instances in the DOM. + * - *Element Injectors*: Each component instance has a Shadow DOM. Within the Shadow DOM each + * element has an `ElementInjector` + * which follow the same parent-child hierarchy as the DOM elements themselves. + * + * When a template is instantiated, it also must instantiate the corresponding directives in a + * depth-first order. The + * current `ElementInjector` resolves the constructor dependencies for each directive. + * + * Angular then resolves dependencies as follows, according to the order in which they appear in the + * {@link ViewMetadata}: + * + * 1. Dependencies on the current element + * 2. Dependencies on element injectors and their parents until it encounters a Shadow DOM boundary + * 3. Dependencies on component injectors and their parents until it encounters the root component + * 4. Dependencies on pre-existing injectors + * + * + * The `ElementInjector` can inject other directives, element-specific special objects, or it can + * delegate to the parent + * injector. + * + * To inject other directives, declare the constructor parameter as: + * - `directive:DirectiveType`: a directive on the current element only + * - `@Host() directive:DirectiveType`: any directive that matches the type between the current + * element and the + * Shadow DOM root. + * - `@Query(DirectiveType) query:QueryList`: A live collection of direct child + * directives. + * - `@QueryDescendants(DirectiveType) query:QueryList`: A live collection of any + * child directives. + * + * To inject element-specific special objects, declare the constructor parameter as: + * - `element: ElementRef` to obtain a reference to logical element in the view. + * - `viewContainer: ViewContainerRef` to control child template instantiation, for + * {@link DirectiveMetadata} directives only + * - `bindingPropagation: BindingPropagation` to control change detection in a more granular way. + * + * ## Example + * + * The following example demonstrates how dependency injection resolves constructor arguments in + * practice. + * + * + * Assume this HTML template: + * + * ``` + *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ * ``` + * + * With the following `dependency` decorator and `SomeService` injectable class. + * + * ``` + * @Injectable() + * class SomeService { + * } + * + * @Directive({ + * selector: '[dependency]', + * inputs: [ + * 'id: dependency' + * ] + * }) + * class Dependency { + * id:string; + * } + * ``` + * + * Let's step through the different ways in which `MyDirective` could be declared... + * + * + * ### No injection + * + * Here the constructor is declared with no arguments, therefore nothing is injected into + * `MyDirective`. + * + * ``` + * @Directive({ selector: '[my-directive]' }) + * class MyDirective { + * constructor() { + * } + * } + * ``` + * + * This directive would be instantiated with no dependencies. + * + * + * ### Component-level injection + * + * Directives can inject any injectable instance from the closest component injector or any of its + * parents. + * + * Here, the constructor declares a parameter, `someService`, and injects the `SomeService` type + * from the parent + * component's injector. + * ``` + * @Directive({ selector: '[my-directive]' }) + * class MyDirective { + * constructor(someService: SomeService) { + * } + * } + * ``` + * + * This directive would be instantiated with a dependency on `SomeService`. + * + * + * ### Injecting a directive from the current element + * + * Directives can inject other directives declared on the current element. + * + * ``` + * @Directive({ selector: '[my-directive]' }) + * class MyDirective { + * constructor(dependency: Dependency) { + * expect(dependency.id).toEqual(3); + * } + * } + * ``` + * This directive would be instantiated with `Dependency` declared at the same element, in this case + * `dependency="3"`. + * + * ### Injecting a directive from any ancestor elements + * + * Directives can inject other directives declared on any ancestor element (in the current Shadow + * DOM), i.e. on the current element, the + * parent element, or its parents. + * ``` + * @Directive({ selector: '[my-directive]' }) + * class MyDirective { + * constructor(@Host() dependency: Dependency) { + * expect(dependency.id).toEqual(2); + * } + * } + * ``` + * + * `@Host` checks the current element, the parent, as well as its parents recursively. If + * `dependency="2"` didn't + * exist on the direct parent, this injection would + * have returned + * `dependency="1"`. + * + * + * ### Injecting a live collection of direct child directives + * + * + * A directive can also query for other child directives. Since parent directives are instantiated + * before child directives, a directive can't simply inject the list of child directives. Instead, + * the directive injects a {@link QueryList}, which updates its contents as children are added, + * removed, or moved by a directive that uses a {@link ViewContainerRef} such as a `ng-for`, an + * `ng-if`, or an `ng-switch`. + * + * ``` + * @Directive({ selector: '[my-directive]' }) + * class MyDirective { + * constructor(@Query(Dependency) dependencies:QueryList) { + * } + * } + * ``` + * + * This directive would be instantiated with a {@link QueryList} which contains `Dependency` 4 and + * 6. Here, `Dependency` 5 would not be included, because it is not a direct child. + * + * ### Injecting a live collection of descendant directives + * + * By passing the descendant flag to `@Query` above, we can include the children of the child + * elements. + * + * ``` + * @Directive({ selector: '[my-directive]' }) + * class MyDirective { + * constructor(@Query(Dependency, {descendants: true}) dependencies:QueryList) { + * } + * } + * ``` + * + * This directive would be instantiated with a Query which would contain `Dependency` 4, 5 and 6. + * + * ### Optional injection + * + * The normal behavior of directives is to return an error when a specified dependency cannot be + * resolved. If you + * would like to inject `null` on unresolved dependency instead, you can annotate that dependency + * with `@Optional()`. + * This explicitly permits the author of a template to treat some of the surrounding directives as + * optional. + * + * ``` + * @Directive({ selector: '[my-directive]' }) + * class MyDirective { + * constructor(@Optional() dependency:Dependency) { + * } + * } + * ``` + * + * This directive would be instantiated with a `Dependency` directive found on the current element. + * If none can be + * found, the injector supplies `null` instead of throwing an error. + * + * ## Example + * + * Here we use a decorator directive to simply define basic tool-tip behavior. + * + * ``` + * @Directive({ + * selector: '[tooltip]', + * inputs: [ + * 'text: tooltip' + * ], + * host: { + * '(mouseenter)': 'onMouseEnter()', + * '(mouseleave)': 'onMouseLeave()' + * } + * }) + * class Tooltip{ + * text:string; + * overlay:Overlay; // NOT YET IMPLEMENTED + * overlayManager:OverlayManager; // NOT YET IMPLEMENTED + * + * constructor(overlayManager:OverlayManager) { + * this.overlay = overlay; + * } + * + * onMouseEnter() { + * // exact signature to be determined + * this.overlay = this.overlayManager.open(text, ...); + * } + * + * onMouseLeave() { + * this.overlay.close(); + * this.overlay = null; + * } + * } + * ``` + * In our HTML template, we can then add this behavior to a `
` or any other element with the + * `tooltip` selector, + * like so: + * + * ``` + *
+ * ``` + * + * Directives can also control the instantiation, destruction, and positioning of inline template + * elements: + * + * A directive uses a {@link ViewContainerRef} to instantiate, insert, move, and destroy views at + * runtime. + * The {@link ViewContainerRef} is created as a result of `