ValueStreamListener<T> class

Takes a ValueStreamWidgetListener and a stream and invokes the listener in response to value changes in the stream.

It should be used for functionality that needs to occur only in response to a value change such as navigation, showing a SnackBar, showing a Dialog, etc...

The listener is guaranteed to only be called once for each value change unlike the builder in ValueStreamBuilder.

ValueStreamListener requires stream.hasValue to always be true, and the stream does not emit any error events. See ValueStreamHasNoValueError and UnhandledStreamError for more information.

Example

ValueStreamListener<T>(
  stream: source,
  listener: (context, previous, current) {
    // do stuff here based on source
    // previous and current values
  },
  child: Container(),
)
Inheritance
Available extensions

Constructors

ValueStreamListener({Key? key, ValueStream<T>? stream, StateStreamable<T>? bloc, required ValueStreamWidgetListener<T> listener, required Widget child, bool isReplayValueStream = true})
Takes a ValueStreamWidgetListener and a stream and invokes the listener in response to value changes in the stream.
const

Properties

bloc → StateStreamable<T>?
Bloc-native state source. Prefer this for new code.
final
child → Widget
The widget which will be rendered as a descendant of the ValueStreamListener.
final
hashCode → int
The hash code for this object.
no setterinherited
isReplayValueStream → bool
Whether or not the stream emits the last value like FlowR streams do.
final
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
listener → ValueStreamWidgetListener<T>
Takes the BuildContext along with the previous and current values and is responsible for executing in response to value changes.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
stream → ValueStream<T>?
The ValueStream that the legacy ValueStreamListener will interact with.
final

Methods

createElement() → StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → State<ValueStreamListener<T>>
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.
inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
override
distinctBy<T>(Object key(T)) → bool Function(T, T)

Available on Widget, provided by the WidgetDistinctByX extension

buildWhen: (p, c) => p.userId != p.userId && p.name != c.name, buildWhen: (p, c) => (p.userId, p.name) != (p.name, c.name), buildWhen: distinctBy((e) => (e.userId, e.name)),
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