ProxyProvider4<T, T2, T3, T4, 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:

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

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

  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:



ProxyProvider4({Key key, Create<R> create, @required ProxyProviderBuilder4<T, T2, T3, T4, R> update, UpdateShouldNotify<R> updateShouldNotify, Dispose<R> dispose, bool lazy, TransitionBuilder builder, Widget child})
Initializes key for subclasses.


builder → TransitionBuilder
Syntax sugar for obtaining a BuildContext that can read the provider created. [...]
final, inherited
hashCode → int
The hash code for this object. [...]
@nonVirtual, read-only, 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.
read-only, inherited


build(BuildContext context) → Widget
Describes the part of the user interface represented by this widget. [...]
buildWithChild(BuildContext context, Widget child) → Widget
A build method that receives an extra child parameter. [...]
createElement() → _InheritedProviderElement<R>
Creates a StatelessElement to manage this widget's location in the tree. [...]
debugDescribeChildren() → List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children. [...]
@protected, inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node. [...]
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent 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
Returns 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. [...]
@nonVirtual, inherited