NgComponent class
Meta-data marker placed on a class which should act as a controller for the component. Angular components are a light-weight version of web-components. Angular components use shadow-DOM for rendering their templates.
Angular components are instantiated using dependency injection, and can ask for any injectable object in their constructor. Components can also ask for other components or directives declared on the DOM element.
Components can declared these optional methods:
-
attach()
- Called on first Scope.$digest(). -
detach()
- Called on when owning scope is destroyed.
class NgComponent extends NgAnnotation { /** * Inlined HTML template for the component. */ final String template; /** * A URL to HTML template. This will be loaded asynchronously and * cached for future component instances. */ final String templateUrl; /** * A CSS URL to load into the shadow DOM. */ final String cssUrl; /** * Set the shadow root applyAuthorStyles property. See shadow-DOM * documentation for further details. */ final bool applyAuthorStyles; /** * Set the shadow root resetStyleInheritance property. See shadow-DOM * documentation for further details. */ final bool resetStyleInheritance; const NgComponent({ this.template, this.templateUrl, this.cssUrl, this.applyAuthorStyles, this.resetStyleInheritance, publishAs, map, selector, visibility, publishTypes : const <Type>[], exportExpressions, exportExpressionAttrs }) : super(selector: selector, children: NgAnnotation.COMPILE_CHILDREN, visibility: visibility, publishTypes: publishTypes, publishAs: publishAs, map: map, exportExpressions: exportExpressions, exportExpressionAttrs: exportExpressionAttrs); }
Extends
NgAnnotation > NgComponent
Constructors
const NgComponent({String template, String templateUrl, String cssUrl, bool applyAuthorStyles, bool resetStyleInheritance, publishAs, map, selector, visibility, publishTypes: const[] , exportExpressions, exportExpressionAttrs}) #
Creates a new Object instance.
Object instances have no meaningful state, and are only useful through their identity. An Object instance is equal to itself only.
const NgComponent({ this.template, this.templateUrl, this.cssUrl, this.applyAuthorStyles, this.resetStyleInheritance, publishAs, map, selector, visibility, publishTypes : const <Type>[], exportExpressions, exportExpressionAttrs }) : super(selector: selector, children: NgAnnotation.COMPILE_CHILDREN, visibility: visibility, publishTypes: publishTypes, publishAs: publishAs, map: map, exportExpressions: exportExpressions, exportExpressionAttrs: exportExpressionAttrs);
Properties
final bool applyAuthorStyles #
Set the shadow root applyAuthorStyles property. See shadow-DOM documentation for further details.
final bool applyAuthorStyles
final String children #
Specifies the compiler action to be taken on the child nodes of the element which this currently being compiled. The values are:
- COMPILE_CHILDREN
TRANSCLUDE_CHILDREN
IGNORE_CHILDREN
final String children
final String cssUrl #
A CSS URL to load into the shadow DOM.
final String cssUrl
final List<String> exportExpressionAttrs #
Use the list to specify expression containing attributes which are not
included under map
with '=' or '@' specification.
final List<String> exportExpressionAttrs
final List<String> exportExpressions #
Use the list to specify a expressions which are evaluated dynamically (ex. via Scope.$eval) and are otherwise not statically discoverable.
final List<String> exportExpressions
final hashCode #
Get a hash code for this object.
All objects have hash codes. Hash codes are guaranteed to be the
same for objects that are equal when compared using the equality
operator ==
. Other than that there are no guarantees about
the hash codes. They will not be consistent between runs and
there are no distribution guarantees.
If a subclass overrides hashCode it should override the equality operator as well to maintain consistency.
get hashCode => selector.hashCode;
final Map<String, String> map #
Use map to define the mapping of DOM attributes to fields. The map's key is the DOM attribute name (DOM attribute is in dash-case). The Map's value consists of a mode prefix followed by an expression. The destination expression will be evaluated against the instance of the directive / component class.
-
@
- Map the DOM attribute string. The attribute string will be taken literally or interpolated if it contains binding {{}} systax and assigned to the expression. (cost: 0 watches) -
=>
- Treat the DOM attribute value as an expression. Set up a watch, which will read the expression in the attribute and assign the value to destination expression. (cost: 1 watch) -
<=>
- Treat the DOM attribute value as an expression. Set up a watch on both outside as well as component scope to keep the src and destination in sync. (cost: 2 watches) -
=>!
- Treat the DOM attribute value as an expression. Set up a one time watch on expression. Once the expression turns truthy it will no longer update. (cost: 1 watches until not null, then 0 watches) -
&
- Treat the DOM attribute value as an expression. Assign a closure function into the field. This allows the component to control the invocation of the closure. This is useful for passing expressions into controllers which act like callbacks. (cost: 0 watches)
Example:
<my-component title="Hello {{username}}"
selection="selectedItem"
on-selection-change="doSomething()">
@NgComponent(
selector: 'my-component'
map: const {
'title': '@title',
'selection': '<=>currentItem',
'on-selection-change': '&onChange'
}
)
class MyComponent {
String title;
var currentItem;
ParsedFn onChange;
}
The above example shows how all three mapping modes are used.
-
@title
maps the title DOM attribute to the controllertitle
field. Notice that this maps the content of the attribute, which means that it can be used with{{}}
interpolation. -
<=>currentItem
maps the expression (in this case theselectedItem
in the current scope into thecurrentItem
in the controller. Notice that mapping is bi-directional. A change either in field or on parent scope will result in change to the other. -
&onChange
maps the expression into tho controllersonChange
field. The result of mapping is a callable function which can be invoked at any time by the controller. The invocation of the callable function will result in the expressiondoSomething()
to be executed in the parent context.
final Map<String, String> map
final String publishAs #
An expression under which the controller instance will be published into. This allows the expressions in the template to be referring to controller instance and its properties.
final String publishAs
final bool resetStyleInheritance #
Set the shadow root resetStyleInheritance property. See shadow-DOM documentation for further details.
final bool resetStyleInheritance
final String selector #
CSS selector which will trigger this component/directive. CSS Selectors are limited to a single element and can contain:
element-name
limit to a given element name..class
limit to an element with a given class.[attribute]
limit to an element with a given attribute name.[attribute=value]
limit to an element with a given attribute and value.
Example: input[type=checkbox][ng-model]
final String selector
final String template #
Inlined HTML template for the component.
final String template
final String templateUrl #
A URL to HTML template. This will be loaded asynchronously and cached for future component instances.
final String templateUrl
final String visibility #
A directive/component controller class can be injected into other directives/components. This attribute controls whether the controller is available to others.
-
local
NgDirective.LOCAL_VISIBILITY - the controller can be injected into other directives / components on the same DOM element. -
children
NgDirective.CHILDREN_VISIBILITY - the controller can be injected into other directives / components on the same or child DOM elements. -
direct_children
[NgDirective.DIRECT_CHILDREN_VISIBILITY] - the controller can be injected into other directives / components on the direct children of the current DOM element.
final String visibility
Operators
dynamic operator ==(other) #
The equality operator.
The default behavior for all Objects is to return true if and
only if this
and
other are the same object.
Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:
-
Total: It must return a boolean for all arguments. It should never throw or return
null
. -
Reflexive: For all objects
o
,o == o
must be true. -
Symmetric: For all objects
o1
ando2
,o1 == o2
ando2 == o1
must either both be true, or both be false. -
Transitive: For all objects
o1
,o2
, ando3
, ifo1 == o2
ando2 == o3
are true, theno1 == o3
must be true.
The method should also be consistent over time, so equality of two objects should not change over time, or at least only change if one of the objects was modified.
If a subclass overrides the equality operator it should override the hashCode method as well to maintain consistency.
operator==(other) => other is NgAnnotation && this.selector == other.selector;
Methods
dynamic toString() #
Returns a string representation of this object.
toString() => selector;