DataTable - Lazy Loading
DataTable has built-in support to deal with huge datasets. In order to enable lazy loading, a LazyDataModel needs to be implemented to query the datasource when pagination, sorting, filtering or live scrolling happens. This example demonstrates uses an in-memory list to mimic a real datasource like a database.
Source
<h:form id="form">
<p:dataTable var="car" value="#{tableBean.lazyModel}" paginator="true" rows="10"
paginatorTemplate="{RowsPerPageDropdown} {FirstPageLink} {PreviousPageLink} {CurrentPageReport} {NextPageLink} {LastPageLink}"
rowsPerPageTemplate="5,10,15" selectionMode="single" selection="#{tableBean.selectedCar}" id="carTable" lazy="true">
<p:ajax event="rowSelect" listener="#{tableBean.onRowSelect}" update=":form:display" oncomplete="carDialog.show()" />
<p:column headerText="Model" sortBy="#{car.model}" filterBy="#{car.model}">
<h:outputText value="#{car.model}" />
</p:column>
<p:column headerText="Year" sortBy="#{car.year}" filterBy="#{car.year}">
<h:outputText value="#{car.year}" />
</p:column>
<p:column headerText="Manufacturer" sortBy="#{car.manufacturer}" filterBy="#{car.manufacturer}">
<h:outputText value="#{car.manufacturer}" />
</p:column>
<p:column headerText="Color" sortBy="#{car.color}" filterBy="#{car.color}">
<h:outputText value="#{car.color}" />
</p:column>
</p:dataTable>
<p:dialog header="Car Detail" widgetVar="carDialog" resizable="false"
showEffect="explode" hideEffect="explode">
<h:panelGrid id="display" columns="2" cellpadding="4">
<f:facet name="header">
<p:graphicImage value="/images/cars/#{tableBean.selectedCar.manufacturer}.jpg"/>
</f:facet>
<h:outputText value="Model:" />
<h:outputText value="#{tableBean.selectedCar.model}" style="font-weight:bold"/>
<h:outputText value="Year:" />
<h:outputText value="#{tableBean.selectedCar.year}" style="font-weight:bold"/>
<h:outputText value="Manufacturer:" />
<h:outputText value="#{tableBean.selectedCar.manufacturer}" style="font-weight:bold"/>
<h:outputText value="Color:" />
<h:outputText value="#{tableBean.selectedCar.color}" style="font-weight:bold"/>
</h:panelGrid>
</p:dialog>
</h:form>
package org.primefaces.examples.view;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.UUID;
import javax.servlet.ServletContext;
import org.primefaces.examples.domain.Car;
import org.primefaces.model.LazyDataModel;
public class TableBean {
private LazyDataModel<Car> lazyModel;
private Car selectedCar;
private List<Car> cars;
static {
colors = new String[10];
colors[0] = "Black";
colors[1] = "White";
colors[2] = "Green";
colors[3] = "Red";
colors[4] = "Blue";
colors[5] = "Orange";
colors[6] = "Silver";
colors[7] = "Yellow";
colors[8] = "Brown";
colors[9] = "Maroon";
manufacturers = new String[10];
manufacturers[0] = "Mercedes";
manufacturers[1] = "BMW";
manufacturers[2] = "Volvo";
manufacturers[3] = "Audi";
manufacturers[4] = "Renault";
manufacturers[5] = "Opel";
manufacturers[6] = "Volkswagen";
manufacturers[7] = "Chrysler";
manufacturers[8] = "Ferrari";
manufacturers[9] = "Ford";
}
public TableBean() {
populateRandomCars(cars, 50);
lazyModel = new LazyCarDataModel(cars);
}
public Car getSelectedCar() {
return selectedCar;
}
public void setSelectedCar(Car selectedCar) {
this.selectedCar = selectedCar;
}
public LazyDataModel<Car> getLazyModel() {
return lazyModel;
}
private void populateRandomCars(List<Car> list, int size) {
for(int i = 0 ; i < size ; i++) {
list.add(new Car(getRandomModel(), getRandomYear(), getRandomManufacturer(), getRandomColor()));
}
}
private String getRandomColor() {
return colors[(int) (Math.random() * 10)];
}
private String getRandomManufacturer() {
return manufacturers[(int) (Math.random() * 10)];
}
private int getRandomYear() {
return (int) (Math.random() * 50 + 1960);
}
}
package org.primefaces.examples.view;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.primefaces.examples.domain.Car;
import org.primefaces.model.LazyDataModel;
import org.primefaces.model.SortOrder;
/**
* Dummy implementation of LazyDataModel that uses a list to mimic a real datasource like a database.
*/
public class LazyCarDataModel extends LazyDataModel<Car> {
private List<Car> datasource;
public LazyCarDataModel(List<Car> datasource) {
this.datasource = datasource;
}
@Override
public Car getRowData(String rowKey) {
for(Car car : datasource) {
if(car.getModel().equals(rowKey))
return car;
}
return null;
}
@Override
public Object getRowKey(Car car) {
return car.getModel();
}
@Override
public List<Car> load(int first, int pageSize, String sortField, SortOrder sortOrder, Map<String,String> filters) {
List<Car> data = new ArrayList<Car>();
//filter
for(Car car : datasource) {
boolean match = true;
for(Iterator<String> it = filters.keySet().iterator(); it.hasNext();) {
try {
String filterProperty = it.next();
String filterValue = filters.get(filterProperty);
String fieldValue = String.valueOf(car.getClass().getField(filterProperty).get(car));
if(filterValue == null || fieldValue.startsWith(filterValue)) {
match = true;
}
else {
match = false;
break;
}
} catch(Exception e) {
match = false;
}
}
if(match) {
data.add(car);
}
}
//sort
if(sortField != null) {
Collections.sort(data, new LazySorter(sortField, sortOrder));
}
//rowCount
int dataSize = data.size();
this.setRowCount(dataSize);
//paginate
if(dataSize > pageSize) {
try {
return data.subList(first, first + pageSize);
}
catch(IndexOutOfBoundsException e) {
return data.subList(first, first + (dataSize % pageSize));
}
}
else {
return data;
}
}
}
