ProxyProvider2<T, T2, R> class

A provider that builds a value based on other providers.

The exposed value is built through either create or update, then passed to InheritedProvider.

As opposed to create, update may be called more than once. It will be called once the first time the value is obtained, then once whenever ProxyProvider rebuilds or when one of the providers it depends on updates.

ProxyProvider comes in different variants such as ProxyProvider2. This is syntax sugar on the top of ProxyProvider0.

As such, ProxyProvider<A, Result> is equal to:

ProxyProvider0<Result>(
  update: (context, result) {
    final a = Provider.of<A>(context);
    return update(context, a, result);
  }
);

Whereas ProxyProvider2<A, B, Result> is equal to:

ProxyProvider0<Result>(
  update: (context, result) {
    final a = Provider.of<A>(context);
    final b = Provider.of<B>(context);
    return update(context, a, b, result);
  }
);

This last parameter of update is the last value returned by either create or update. It is null by default.

update must not be null.

See also:

• Provider, which matches the behavior of ProxyProvider but has only a create callback.

Inheritance

• Object
• DiagnosticableTree
• Widget
• StatelessWidget
• SingleChildStatelessWidget
• InheritedProvider<R>
• ProxyProvider0<R>
• ProxyProvider2

Implemented types

• Widget

Constructors

ProxyProvider2({Key? key, Create<R>? create, required ProxyProviderBuilder2<T, T2, R> update, UpdateShouldNotify<R>? updateShouldNotify, Dispose<R>? dispose, bool? lazy, TransitionBuilder? builder, Widget? child})

Initializes key for subclasses.

Properties

builder → TransitionBuilder?

Syntax sugar for obtaining a BuildContext that can read the provider created.

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

Methods

build(BuildContext context) → Widget

Describes the part of the user interface represented by this widget.

inherited

buildWithChild(BuildContext context, Widget? child) → Widget

A build method that receives an extra child parameter.

inherited

createElement() → _InheritedProviderElement<R>

Creates a StatelessElement to manage this widget's 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