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 uses an in-memory list to mimic a real datasource like a database.
In a real application, loading should be executed with the query built using the information passed to the load method.
Documentation<h:form id="form"> <p:dataTable var="car" value="#{dtLazyView.lazyModel}" paginator="true" rows="10" paginatorTemplate="{RowsPerPageDropdown} {FirstPageLink} {PreviousPageLink} {CurrentPageReport} {NextPageLink} {LastPageLink}" rowsPerPageTemplate="5,10,15" selectionMode="single" selection="#{dtLazyView.selectedCar}" id="carTable" lazy="true"> <p:ajax event="rowSelect" listener="#{dtLazyView.onRowSelect}" update=":form:carDetail" oncomplete="PF('carDialog').show()" /> <p:column headerText="Id" sortBy="#{car.id}" filterBy="#{car.id}"> <h:outputText value="#{car.id}" /> </p:column> <p:column headerText="Year" sortBy="#{car.year}" filterBy="#{car.year}"> <h:outputText value="#{car.year}" /> </p:column> <p:column headerText="Brand" sortBy="#{car.brand}" filterBy="#{car.brand}"> <h:outputText value="#{car.brand}" /> </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" modal="true" showEffect="fade" hideEffect="fade" resizable="false"> <p:outputPanel id="carDetail" style="text-align:center;"> <p:panelGrid columns="2" rendered="#{not empty dtLazyView.selectedCar}" columnClasses="label,value"> <f:facet name="header"> <p:graphicImage name="demo/images/car/#{dtLazyView.selectedCar.brand}-big.gif"/> </f:facet> <h:outputText value="Id:" /> <h:outputText value="#{dtLazyView.selectedCar.id}" /> <h:outputText value="Year" /> <h:outputText value="#{dtLazyView.selectedCar.year}" /> <h:outputText value="Color:" /> <h:outputText value="#{dtLazyView.selectedCar.color}" style="color:#{dtLazyView.selectedCar.color}"/> <h:outputText value="Price:" /> <h:outputText value="#{dtLazyView.selectedCar.price}"> <f:convertNumber type="currency" currencySymbol="$" /> </h:outputText> </p:panelGrid> </p:outputPanel> </p:dialog> </h:form>
@Named("dtLazyView") @ViewScoped public class LazyView implements Serializable { private LazyDataModel<Car> lazyModel; private Car selectedCar; @Inject private CarService service; @PostConstruct public void init() { lazyModel = new LazyCarDataModel(service.createCars(200)); } public LazyDataModel<Car> getLazyModel() { return lazyModel; } public Car getSelectedCar() { return selectedCar; } public void setSelectedCar(Car selectedCar) { this.selectedCar = selectedCar; } public void setService(CarService service) { this.service = service; } public void onRowSelect(SelectEvent<Car> event) { FacesMessage msg = new FacesMessage("Car Selected", event.getObject().getId()); FacesContext.getCurrentInstance().addMessage(null, msg); } }
public class Car implements Serializable { public String id; public String brand; public int year; public String color; public int price; public boolean sold; public Car() {} public Car(String id, String brand, int year, String color) { this.id = id; this.brand = brand; this.year = year; this.color = color; } public Car(String id, String brand, int year, String color, int price, boolean sold) { this.id = id; this.brand = brand; this.year = year; this.color = color; this.price = price; this.sold = sold; } public String getId() { return id; } public void setId(String id) { this.id = id; } public String getBrand() { return brand; } public void setBrand(String brand) { this.brand = brand; } public int getYear() { return year; } public void setYear(int year) { this.year = year; } public String getColor() { return color; } public void setColor(String color) { this.color = color; } public int getPrice() { return price; } public void setPrice(int price) { this.price = price; } public boolean isSold() { return sold; } public void setSold(boolean sold) { this.sold = sold; } @Override public int hashCode() { int hash = 7; hash = 59 * hash + (this.id != null ? this.id.hashCode() : 0); return hash; } @Override public boolean equals(Object obj) { if (obj == null) { return false; } if (getClass() != obj.getClass()) { return false; } final Car other = (Car) obj; if ((this.id == null) ? (other.id != null) : !this.id.equals(other.id)) { return false; } return true; } }
@Named @ApplicationScoped public class CarService { private final static String[] colors; private final static String[] brands; 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"; brands = new String[10]; brands[0] = "BMW"; brands[1] = "Mercedes"; brands[2] = "Volvo"; brands[3] = "Audi"; brands[4] = "Renault"; brands[5] = "Fiat"; brands[6] = "Volkswagen"; brands[7] = "Honda"; brands[8] = "Jaguar"; brands[9] = "Ford"; } public List<Car> createCars(int size) { List<Car> list = new ArrayList<Car>(); for(int i = 0 ; i < size ; i++) { list.add(new Car(getRandomId(), getRandomBrand(), getRandomYear(), getRandomColor(), getRandomPrice(), getRandomSoldState())); } return list; } private String getRandomId() { return UUID.randomUUID().toString().substring(0, 8); } private int getRandomYear() { return (int) (Math.random() * 50 + 1960); } private String getRandomColor() { return colors[(int) (Math.random() * 10)]; } private String getRandomBrand() { return brands[(int) (Math.random() * 10)]; } private int getRandomPrice() { return (int) (Math.random() * 100000); } private boolean getRandomSoldState() { return (Math.random() > 0.5) ? true: false; } public List<String> getColors() { return Arrays.asList(colors); } public List<String> getBrands() { return Arrays.asList(brands); } }
public class LazySorter implements Comparator<Car> { private String sortField; private SortOrder sortOrder; public LazySorter(String sortField, SortOrder sortOrder) { this.sortField = sortField; this.sortOrder = sortOrder; } public int compare(Car car1, Car car2) { try { Object value1 = Car.class.getField(this.sortField).get(car1); Object value2 = Car.class.getField(this.sortField).get(car2); int value = ((Comparable)value1).compareTo(value2); return SortOrder.ASCENDING.equals(sortOrder) ? value : -1 * value; } catch(Exception e) { throw new RuntimeException(); } } }
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.getId().equals(rowKey)) { return car; } } return null; } @Override public Object getRowKey(Car car) { return car.getId(); } @Override public List<Car> load(int first, int pageSize, Map<String, SortMeta> sortMeta, Map<String, FilterMeta> filterMeta) { List<Car> data = new ArrayList<>(); //filter for (Car car : datasource) { boolean match = true; if (filterMeta != null) { for (FilterMeta meta : filterMeta.values()) { try { String filterField = meta.getFilterField(); Object filterValue = meta.getFilterValue(); String fieldValue = String.valueOf(car.getClass().getField(filterField).get(car)); if (filterValue == null || fieldValue.startsWith(filterValue.toString())) { match = true; } else { match = false; break; } } catch (Exception e) { match = false; } } } if (match) { data.add(car); } } //sort if (sortMeta != null && !sortMeta.isEmpty()) { for (SortMeta meta : sortMeta.values()) { Collections.sort(data, new LazySorter(meta.getSortField(), meta.getSortOrder())); } } //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; } } }