Selector5<A, B, C, D, E, S> constructor

Selector5<A, B, C, D, E, S>({
  1. Key? key,
  2. required ValueWidgetBuilder<S> builder,
  3. required S selector(
    1. BuildContext,
    2. A,
    3. B,
    4. C,
    5. D,
    6. E,
    ),
  4. ShouldRebuild<S>? shouldRebuild,
  5. 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.

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

In this example builder will be called only when foo.bar 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.

Implementation

Selector5({
  Key? key,
  required ValueWidgetBuilder<S> builder,
  required S Function(BuildContext, A, B, C, D, E) selector,
  ShouldRebuild<S>? shouldRebuild,
  Widget? child,
}) : super(
        key: key,
        shouldRebuild: shouldRebuild,
        builder: builder,
        selector: (context) => selector(
          context,
          Provider.of(context),
          Provider.of(context),
          Provider.of(context),
          Provider.of(context),
          Provider.of(context),
        ),
        child: child,
      );