Selector<A, S> class

An equivalent to Consumer that can filter updates by selecting a limited amount of values and prevent rebuild if they don't change.

Selector will obtain a value using Provider.of, then pass that value to selector. That selector callback is then tasked to return an object that contains only the information needed for builder to complete.

By default, Selector determines if builder needs to be called again by comparing the previous and new result of selector using DeepCollectionEquality from the package collection.

This behavior can be overridden by passing a custom shouldRebuild callback.

NOTE: The selected value must be immutable, or otherwise Selector may think nothing changed and not call builder again.

As such, it selector should return either a collection (List/Map/Set/Iterable) or a class that override ==.

To select multiple values without having to write a class that implements ==, the easiest solution is to use a "Tuple" from tuple:

Selector<Foo, Tuple2<Bar, Baz>>(
  selector: (_, foo) => Tuple2(foo.bar, foo.baz),
  builder: (_, data, __) {
    return Text('${data.item1}  ${data.item2}');
  }
)

In that example, builder will be called again only if foo.bar or foo.baz changes.

For generic usage information, see Consumer.

Inheritance

• Object
• DiagnosticableTree
• Widget
• StatefulWidget
• SingleChildStatefulWidget
• Selector0<S>
• Selector

Constructors

Selector({Key? key, required ValueWidgetBuilder<S> builder, required S selector(BuildContext, A), ShouldRebuild<S>? shouldRebuild, Widget? child})

An equivalent to Consumer that can filter updates by selecting a limited amount of values and prevent rebuild if they don't change.

Properties

builder → ValueWidgetBuilder<S>

A function that builds a widget tree from child and the last result of selector.

final, inherited

hashCode → int

The hash code for this object.

no setter, inherited

key → Key?

Controls how one widget replaces another widget in the tree.

final, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

selector → S Function(BuildContext)

A function that obtains some InheritedWidget and map their content into a new object with only a limited number of properties.

final, inherited

Methods

createElement() → SingleChildStatefulElement

Creates a StatefulElement to manage this widget's location in the tree.

inherited

createState() → _Selector0State<S>

Creates the mutable state for this widget at a given location in the tree.

inherited

debugDescribeChildren() → List<DiagnosticsNode>

Returns a list of DiagnosticsNode objects describing this node's children.

inherited

debugFillProperties(DiagnosticPropertiesBuilder properties) → void

Add additional properties associated with the node.

inherited

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode

Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.

inherited

toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String

A string representation of this object.

inherited

toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug, int wrapWidth = 65}) → String

Returns a string representation of this node and its descendants.

inherited

toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String

Returns a one-line detailed description of the object.

inherited

toStringShort() → String

A short, textual description of this widget.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited