Package com.vaadin.flow.server.data

Class AbstractDataFetchEvent

java.lang.Object

java.util.EventObject

com.vaadin.flow.server.data.AbstractDataFetchEvent

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

DataFetchEndedEvent, DataFetchFailedEvent, DataFetchStartedEvent

public abstract class AbstractDataFetchEvent
extends EventObject

Details shared by the events fired around a fetch query issued to a data provider, that is a query loading one page of items.

getOffset() and getLimit() say what was asked for; DataFetchEndedEvent.getRowsReturned() says what came back. A component that repeatedly asks for far more than it renders, or a data provider that returns short pages, both show up as a gap between the two.

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 DataFetchStartedEvent, DataFetchFailedEvent or DataFetchEndedEvent 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	AbstractDataFetchEvent(UI ui, Component component, int offset, int limit, boolean filtered)	Creates a new fetch event.

Method Summary

Modifier and Type	Method	Description
Optional<Component>	getComponent()	Gets the component whose data is being fetched, so that an observer can attribute the query to a Grid, ComboBox or TreeGrid rather than only to the request.
int	getLimit()	Gets the number of items requested.
int	getOffset()	Gets the index of the first item requested.
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 loading matches for what the user typed from one loading 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

AbstractDataFetchEvent

protected AbstractDataFetchEvent(UI ui,
 Component component,
 int offset,
 int limit,
 boolean filtered)

Creates a new fetch event.

Parameters:

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

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

offset - the index of the first item requested

limit - the number of items requested

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 fetched, 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

getOffset

public int getOffset()

Gets the index of the first item requested.

Returns:

the offset, never negative

getLimit

public int getLimit()

Gets the number of items requested. The data provider may return fewer; compare against DataFetchEndedEvent.getRowsReturned().

Returns:

the limit, never negative

isFiltered

public boolean isFiltered()

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

Returns:

true if the query carried a filter