Actions class Null safety
A widget that establishes an ActionDispatcher and a map of Intent to Action to be used by its descendants when invoking an Action.
Actions are typically invoked using Actions.invoke with the context containing the ambient Actions widget.
ModifyAction
for modifying
a model, and another, SaveAction
for saving it.
This example demonstrates passing arguments to the Intent to be carried to
the Action. Actions can get data either from their own construction (like
the model
in this example), or from the intent passed to them when invoked
(like the increment amount
in this example).
This example also demonstrates how to use Intents to limit a widget's
dependencies on its surroundings. The SaveButton
widget defined in this
example can invoke actions defined in its ancestor widgets, which can be
customized to match the part of the widget tree that it is in. It doesn't
need to know about the SaveAction
class, only the SaveIntent
, and it
only needs to know about a value notifier, not the entire model.
flutter create --sample=widgets.Actions.1 mysample
See also:
- ActionDispatcher, the object that this widget uses to manage actions.
- Action, a class for containing and defining an invocation of a user action.
- Intent, a class that holds a unique LocalKey identifying an action, as well as configuration information for running the Action.
- Shortcuts, a widget used to bind key combinations to Intents.
- Inheritance
-
- Object
- DiagnosticableTree
- Widget
- StatefulWidget
- Actions
Constructors
Properties
-
actions
→ Map<
Type, Action< Intent> > -
A map of Intent keys to
Action<Intent>
objects that defines which actions this widget knows about.final - child → Widget
-
This widget can only have one child. To lay out multiple children, let this
widget's child be a widget such as Row, Column, or Stack, which have a
children
property, and then provide the children to that widget.final - dispatcher → ActionDispatcher?
-
The ActionDispatcher object that invokes actions.
final
- hashCode → int
- The hash code for this object.
- key → Key?
-
Controls how one widget replaces another widget in the tree.
finalinherited
- runtimeType → Type
-
A representation of the runtime type of the object.
read-onlyinherited
Methods
-
createElement(
) → StatefulElement -
Creates a StatefulElement to manage this widget's location in the tree.
inherited
-
createState(
) → State< Actions> -
Creates the mutable state for this widget at a given location in the tree.
override
-
debugDescribeChildren(
) → List< DiagnosticsNode> -
Returns a list of
DiagnosticsNode
objects describing this node's children.protected">@protectedinherited -
debugFillProperties(
DiagnosticPropertiesBuilder properties) → void -
Add additional properties associated with the node.
override
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a non-existent 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}) → 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.
nonVirtual">@nonVirtualinherited
Static Methods
-
find<
T extends Intent> (BuildContext context, {T? intent}) → Action< T> -
Finds the Action bound to the given intent type
T
in the givencontext
. -
handler<
T extends Intent> (BuildContext context, T intent) → VoidCallback? -
Returns a VoidCallback handler that invokes the bound action for the
given
intent
if the action is enabled, and returns null if the action is not enabled, or no matching action is found. -
invoke<
T extends Intent> (BuildContext context, T intent) → Object? - Invokes the action associated with the given Intent using the Actions widget that most tightly encloses the given BuildContext.
-
maybeFind<
T extends Intent> (BuildContext context, {T? intent}) → Action< T> ? -
Finds the Action bound to the given intent type
T
in the givencontext
. -
maybeInvoke<
T extends Intent> (BuildContext context, T intent) → Object? - Invokes the action associated with the given Intent using the Actions widget that most tightly encloses the given BuildContext.
-
of(
BuildContext context) → ActionDispatcher - Returns the ActionDispatcher associated with the Actions widget that most tightly encloses the given BuildContext.