Package com.vaadin.flow.server.data

Class AbstractDataCountEvent

java.lang.Object

java.util.EventObject

com.vaadin.flow.server.data.AbstractDataCountEvent

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

DataCountEndedEvent, DataCountFailedEvent, DataCountStartedEvent

public abstract class AbstractDataCountEvent
extends EventObject

Details shared by the events fired around a count query issued to a data provider, that is a query asking how many items a level holds rather than for the items themselves.

A flat component issues one count query per level reload. A hierarchical component issues one per expanded parent, so several count events for one component within a single request is the signature of an expensive hierarchy.

The events carry only plain values and the resolved Component, never the query or the data provider, so that observers cannot retain or mutate loading state.

This type cannot be listened for. The service event bus dispatches by exact runtime type, so a listener registered for this class is never notified; register for DataCountStartedEvent, DataCountFailedEvent or DataCountEndedEvent instead.

Since:

25.3

See Also:

• Serialized Form

Field Summary

Fields inherited from class java.util.EventObject

source

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractDataCountEvent(UI ui, Component component, boolean filtered)	Creates a new count event.

Method Summary

Modifier and Type	Method	Description
Optional<Component>	getComponent()	Gets the component whose data is being counted, so that an observer can attribute the query to a Grid, ComboBox or TreeGrid rather than only to the request.
UI	getSource()	Gets the UI from which this event originates.
UI	getUI()	Gets the UI from which this event originates.
boolean	isFiltered()	Tells whether a filter was set on the query, which distinguishes a combo box counting matches for what the user typed from one counting the whole data set.

Methods inherited from class java.util.EventObject

toString

Methods inherited from class java.lang.Object

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

Constructor Details

AbstractDataCountEvent

protected AbstractDataCountEvent(UI ui,
 Component component,
 boolean filtered)

Creates a new count event.

Parameters:

ui - the UI the counting component belongs to, not null

component - the component whose data is being counted, or null if it could not be resolved

filtered - whether a filter was set on the query

Method Details

getSource

public UI getSource()

Gets the UI from which this event originates.

Overrides:

getSource in class EventObject

Returns:

the UI, never null

getUI

public UI getUI()

Gets the UI from which this event originates.

Returns:

the UI, never null

getComponent

public Optional<Component> getComponent()

Gets the component whose data is being counted, so that an observer can attribute the query to a Grid, ComboBox or TreeGrid rather than only to the request.

Empty when the component could not be resolved from the state node, for example when the data communicator is driven by a bare element.

Returns:

the component, or an empty optional

isFiltered

public boolean isFiltered()

Tells whether a filter was set on the query, which distinguishes a combo box counting matches for what the user typed from one counting the whole data set.

Returns:

true if the query carried a filter