Package com.vaadin.flow.internal.nodefeature

Class SignalBindingFeature

java.lang.Object

com.vaadin.flow.internal.nodefeature.NodeFeature

com.vaadin.flow.internal.nodefeature.ServerSideFeature

com.vaadin.flow.internal.nodefeature.SignalBindingFeature

All Implemented Interfaces:

Serializable

@NullMarked
public class SignalBindingFeature
extends ServerSideFeature

Node feature for binding Signals to various properties of a node.

For internal use only. May be renamed or removed in a future release.

Since:

25.1

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static final String	CHILDREN
static final String	CLASS_GROUP
static final String	CLASSES
static final String	ENABLED
static final String	HTML_CONTENT
static final String	SIZE	Cache slot for the signal returned by Element.sizeSignal(), not a rendered binding like the other keys: the value flows from the client to the signal through a resize trigger instead of from the signal to a client-side property, and nothing reads the binding except sizeSignal() itself, which uses it to return the same signal for every call.
static final String	TEXT
static final String	THEME_GROUP
static final String	THEMES
static final String	VALUE

Constructor Summary

Constructors

Constructor	Description
SignalBindingFeature(StateNode node)	Creates a SignalBindingFeature for the given node.

Method Summary

Modifier and Type	Method	Description
<T extends @Nullable Object> @Nullable Signal<T>	getSignal(String key)	Gets the signal bound to the given key.
<T> @Nullable SerializableConsumer<T>	getWriteCallback(String key)	Gets the write callback for the given key.
boolean	hasAnyBinding(String keyPrefix)	Checks whether there is any binding with a key starting with the given prefix.
boolean	hasBinding(String key)	Checks whether there is a binding for the given key.
void	setBinding(String key, Signal<?> signal)	Sets a binding for the given key.
void	setBinding(String key, Signal<?> signal, @Nullable SerializableConsumer<?> writeCallback)	Sets a binding for the given key with a write callback.
<T extends @Nullable Object> boolean	updateSignalByWriteCallback(String key, T oldValue, T newValue, SerializableBiPredicate<T,T> valueEquals, SerializableConsumer<T> revertCallback)	Updates the signal value by invoking the write callback for the given key.

Methods inherited from class com.vaadin.flow.internal.nodefeature.ServerSideFeature

collectChanges, forEachChild, generateChangesFromEmpty

Methods inherited from class com.vaadin.flow.internal.nodefeature.NodeFeature

allowsChanges, attachPotentialChild, detatchPotentialChild, getNode, onAttach, onDetach

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

TEXT

public static final String TEXT

See Also:

• Constant Field Values

CLASSES

public static final String CLASSES

See Also:

• Constant Field Values

CLASS_GROUP

public static final String CLASS_GROUP

See Also:

• Constant Field Values

ENABLED

public static final String ENABLED

See Also:

• Constant Field Values

VALUE

public static final String VALUE

See Also:

• Constant Field Values

THEMES

public static final String THEMES

See Also:

• Constant Field Values

THEME_GROUP

public static final String THEME_GROUP

See Also:

• Constant Field Values

HTML_CONTENT

public static final String HTML_CONTENT

See Also:

• Constant Field Values

CHILDREN

public static final String CHILDREN

See Also:

• Constant Field Values

SIZE

public static final String SIZE

Cache slot for the signal returned by Element.sizeSignal(), not a rendered binding like the other keys: the value flows from the client to the signal through a resize trigger instead of from the signal to a client-side property, and nothing reads the binding except sizeSignal() itself, which uses it to return the same signal for every call.

Since:

25.3

See Also:

• Constant Field Values

Constructor Details

SignalBindingFeature

public SignalBindingFeature(StateNode node)

Creates a SignalBindingFeature for the given node.

Parameters:

node - the node which supports the feature

Method Details

setBinding

public void setBinding(String key,
 Signal<?> signal)

Sets a binding for the given key.

Parameters:

key - the key

signal - the signal

setBinding

public void setBinding(String key,
 Signal<?> signal,
 @Nullable SerializableConsumer<?> writeCallback)

Sets a binding for the given key with a write callback.

Parameters:

key - the key

signal - the signal

writeCallback - the callback to propagate value changes back, or null for a read-only binding

hasBinding

public boolean hasBinding(String key)

Checks whether there is a binding for the given key.

Parameters:

key - the key

Returns:

true if there is a binding for the given key, false otherwise

hasAnyBinding

public boolean hasAnyBinding(String keyPrefix)

Checks whether there is any binding with a key starting with the given prefix.

Parameters:

keyPrefix - the key prefix

Returns:

true if there is any binding with a key starting with the given prefix, false otherwise

getWriteCallback

public <T> @Nullable SerializableConsumer<T> getWriteCallback(String key)

Gets the write callback for the given key.

Type Parameters:

T - the type of the consumer value

Parameters:

key - the key

Returns:

the write callback for the given key, or null if no callback is set

getSignal

public <T extends @Nullable Object>
@Nullable Signal<T> getSignal(String key)

Gets the signal bound to the given key.

Type Parameters:

T - the type of the signal value

Parameters:

key - the key

Returns:

the signal bound to the given key, or null if no signal is bound

updateSignalByWriteCallback

public <T extends @Nullable Object> boolean updateSignalByWriteCallback(String key,
 T oldValue,
 T newValue,
 SerializableBiPredicate<T,T> valueEquals,
 SerializableConsumer<T> revertCallback)

Updates the signal value by invoking the write callback for the given key. The callback is expected to update the signal value, and this method will check whether the signal value was updated to the expected new value. If the signal value differs from the expected new value after the callback, the revert callback will be invoked with the current signal value to revert the change.

The new value may originate from the client, in which case there is no guarantee that its type matches the value type of the bound signal. The write callback rejects such a value either with a ClassCastException from the cast that the compiler generated into the callback or with an InvalidSignalValueTypeException from the signal itself when generic code has erased that cast. Since the only purpose of the callback is to pass the value on to the signal, both cases are logged and reverted rather than propagated.

Type Parameters:

T - the type of the signal value

Parameters:

key - the key for which to update the signal value

oldValue - the old value before the update, used for comparison in case of revert

newValue - the expected new value to be set by the write callback

valueEquals - a predicate to compare signal values for equality

revertCallback - a callback to revert the component value to the updated signal's value if the signal value does not match the expected new value after invoking the write callback

Returns:

true if the signal value was updated to the expected new value, false if a revert was performed