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 ==.

Here's an example:

Example 1:

Selector<Foo, Bar>(
  selector: (_, foo) =>,  // will rebuild only when `bar` changes
  builder: (_, data, __) {
    return Text('${data.item}');

In this example builder will be called only when changes.

Example 2:

To select multiple values without having to write a class that implements ==, the easiest solution is to use "Records," available from Dart version 3.0. For more information on Records, refer to the records.

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

In this example, builder will be called again only if foo.item1 or foo.item2 changes.

For generic usage information, see Consumer.



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.


builder ValueWidgetBuilder<S>
A function that builds a widget tree from child and the last result of selector.
hashCode int
The hash code for this object.
no setterinherited
key Key?
Controls how one widget replaces another widget in the tree.
runtimeType Type
A representation of the runtime type of the object.
no setterinherited
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.


createElement() SingleChildStatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
createState() → _Selector0State<S>
Creates the mutable state for this widget at a given location in the tree.
debugDescribeChildren() List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
toString({DiagnosticLevel minLevel =}) String
A string representation of this object.
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) String
Returns a string representation of this node and its descendants.
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) String
Returns a one-line detailed description of the object.
toStringShort() String
A short, textual description of this widget.


operator ==(Object other) bool
The equality operator.