com.vaadin.flow.component.combobox.dataview.ComboBoxLazyDataView Maven / Gradle / Ivy
/*
* Copyright 2000-2024 Vaadin Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.vaadin.flow.component.combobox.dataview;
import java.util.stream.Stream;
import com.vaadin.flow.component.Component;
import com.vaadin.flow.component.ComponentEventListener;
import com.vaadin.flow.data.provider.AbstractLazyDataView;
import com.vaadin.flow.data.provider.BackEndDataProvider;
import com.vaadin.flow.data.provider.CallbackDataProvider;
import com.vaadin.flow.data.provider.DataCommunicator;
import com.vaadin.flow.data.provider.DataProvider;
import com.vaadin.flow.data.provider.HasLazyDataView;
import com.vaadin.flow.data.provider.ItemCountChangeEvent;
import com.vaadin.flow.data.provider.Query;
import com.vaadin.flow.shared.Registration;
/**
* Data view implementation for ComboBox with lazy data fetching. Provides
* information on the data and allows operations on it.
*
* @param
* the type of the items in ComboBox
*/
public class ComboBoxLazyDataView extends AbstractLazyDataView {
/**
* Creates a new lazy data view for ComboBox and verifies the passed data
* provider is compatible with this data view implementation.
*
* @param dataCommunicator
* the data communicator of the component
* @param component
* the ComboBox
*/
public ComboBoxLazyDataView(DataCommunicator dataCommunicator,
Component component) {
super(dataCommunicator, component);
}
/**
* Sets a callback that the combo box uses to get the exact item count in
* the backend. Use this when it is cheap to get the exact item count and it
* is desired that the user sees the "full scrollbar size".
*
* The given callback will be queried for the count instead of the data
* provider {@link DataProvider#size(Query)} method when the component has a
* distinct data provider set with
* {@link HasLazyDataView#setItems(BackEndDataProvider)}.
*
* @param callback
* the callback to use for determining item count in the backend,
* not {@code null}
* @see #setItemCountFromDataProvider()
* @see #setItemCountUnknown()
*/
public void setItemCountCallback(
CallbackDataProvider.CountCallback callback) {
getDataCommunicator().setCountCallback(callback);
}
/**
* {@inheritDoc}
*
* Calling this method will clear any previously set count callback with the
* {@link #setItemCountCallback(CallbackDataProvider.CountCallback)} method.
*/
@Override
public void setItemCountFromDataProvider() {
super.setItemCountFromDataProvider();
}
/**
* {@inheritDoc}
*
* Calling this method will clear any previously set count callback
* {@link #setItemCountCallback(CallbackDataProvider.CountCallback)}.
*/
@Override
public void setItemCountEstimate(int itemCountEstimate) {
super.setItemCountEstimate(itemCountEstimate);
}
/**
* {@inheritDoc}
*
* Calling this method will clear any previously set count callback
* {@link #setItemCountCallback(CallbackDataProvider.CountCallback)}.
*/
@Override
public void setItemCountUnknown() {
super.setItemCountUnknown();
}
/**
* {@inheritDoc}
*
* Combo box fires {@link ItemCountChangeEvent} and notifies all the
* listeners added by this method, if the items count changed, for instance,
* due to fetching more items while scrolling with unknown item count.
*
* ComboBox's client-side filter change won't fire
* {@link ItemCountChangeEvent}, since it doesn't change the item count on
* the server-side, but only makes it easier for users to search through the
* items in the UI.
*/
@Override
public Registration addItemCountChangeListener(
ComponentEventListener> listener) {
return super.addItemCountChangeListener(listener);
}
/**
* Gets the item at the given index from the data available in the
* ComboBox's server-side.
*
* This method does not take into account the ComboBox client-side
* filtering, since it doesn't change the item count on the server-side, but
* only makes it easier for users to search through the items in the UI.
*
* @param index
* item index number
* @return item on index
* @throws IndexOutOfBoundsException
* requested index is outside of the data set
*/
@Override
public T getItem(int index) {
return ItemFetchHelper.getItem(getDataCommunicator(), index);
}
/**
* Gets the items available on the ComboBox's server-side.
*
* This method does not take into account the ComboBox client-filtering,
* since it doesn't change the item count on the server-side, but only makes
* it easier for users to search through the items in the UI.
*
* @return items available on the server-side
*/
@Override
public Stream getItems() {
return ItemFetchHelper.getItems(getDataCommunicator());
}
}