Naviagting an af:table in pagination mode from a bean

A question on the JDeveloper and ADF OTN forum asked about how to navigate to a specific page of an af:table in pagination mode. As of JDeveloper adf tables can be rendered in scroll mode or in pagination mode where only a specific number of rows are visible in the table.

af:table in pagination mode

To navigate the pages there is a small navigation toolbar below the table which allows to enter a page number or to navigate to the previous, next, first or last page.

The problem to solve is how to navigate the paginated table from within a java bean?

The table doesn’t offer any navigation listeners or methods you can bind bean methods to. Luckily there is the RangeChangeEvent one of the FacesEvents which can e used to notify a component that change in the range has taken place.

All we have to do to navigate the table in pagination mode is to calculate the needed parameters

  • oldStart: The previous start of this UIComponent’s selected range, inclusive
  • oldEnd: The previous end of this UIComponent’s selected range, exclusive
  • newStart: The new start of this UIComponent’s selected range, inclusive
  • newEnd: The new end of this UIComponent’s selected range, exclusive

We add an input field to the page which allow us to enter a page number and a button which we use to call an action listener in a bean.

The running application looks like

Running application

Another button is used to calculate the index of the selected row in the whole rowset, the index on the page and the page number. The row index and the index of the row on the page are zero based, page numbers start with 1. Let’s look at the code:

public void onGotoPage(ActionEvent actionEvent) {
BindingContainer bindingContainer = BindingContext.getCurrent().getCurrentBindingsEntry();
// get number of page to goto
AttributeBinding attr = (AttributeBinding) bindingContainer.getControlBinding("gotopage1");
Integer newPage = (Integer) attr.getInputValue();
if (newPage == null) {
// page one starts at index 0 so subtract 1 from the pagen number
DCIteratorBinding iter = (DCIteratorBinding) bindingContainer.get("EmployeesView1Iterator");
// calculate the old and new rages for the RangeChangeEvent
int range = iter.getRangeSize(); // note both the table and we take the page size from the iterator's RangeSize
int oldStart = iter.getRangeStart();
int oldEnd = oldStart + range;
int newStart = newPage * range;
int newEnd = newStart + range;
// find the table
UIViewRoot iViewRoot = FacesContext.getCurrentInstance().getViewRoot();
UIComponent table = iViewRoot.findComponent("t1");
// build the event and fire it
RangeChangeEvent event = new RangeChangeEvent(table, oldStart, oldEnd, newStart, newEnd);
// update the table

Line 2-8 we get the new page number we want to navigate to. Line 9-10 we subtract 1 from the given number as the page is zero based internally. In Line 11 we get the iterator which we need to get the range size and the start of the current range (lines 13-15). These values are oldStart and oldEnd. Lines 16-17 we calculate the new start range as page to go multiplied with the range. The newEnd parameter is the newStart pus the range size.
In lines 18-20 we get to the table component on the page. Then we create the RangeChangeEvent and broadcast the event to the table component in lines 21-23. Finally we ppr the table to see the change in the UI.

To show how to calculate the other way around, to get from the selected row in a table to the index on the page, the page number and the index in the rowset we added another button ‘GetPageOfSelectedRow’which calls a listener in the same bean which builds a string with the needed information.

public void onGetCurrentPage(ActionEvent actionEvent) {
BindingContainer bindingContainer = BindingContext.getCurrent().getCurrentBindingsEntry();
DCIteratorBinding iter = (DCIteratorBinding) bindingContainer.get("EmployeesView1Iterator");
// calculate index and page number. Index is zero based!
int currentRowIndex = iter.getRowSetIterator().getCurrentRowIndex();"CurrentRowIndex: " + currentRowIndex);
int currentPage = currentRowIndex / iter.getRangeSize();
currentPage++;"Current Page:" + currentPage);
int indexOnPage = (currentRowIndex % iter.getRangeSize());"Current index on Page:" + indexOnPage);
// get an ADF attributevalue from the ADF page definitions
AttributeBinding attr = (AttributeBinding) bindingContainer.getControlBinding("selectedRow1");
StringBuffer sb = new StringBuffer();
sb.append("row index overall: ");
sb.append(" row index on page: ");
sb.append(" Page: ");

To get the index of the selected row in the whole rowset we need the iterator and get the RowSetIterator from it. The rowSetIterator method getCurrentRowIndex() returns the index of the current row (line 5). The current page is calculated by dividing the current index through the range size (line 7). The final information is the index of the selected row on the page which is calculated as the current index modulo the range size (line 10). The rest of the listener build a string out of this information and writes it to a pageDef variable which is referenced in an outputfield on the page.

<af:outputText value="#{bindings.selectedRow1.inputValue}" id="ot8" partialTriggers="b2"/>

Here are some images from the sample application.

The sample application is build using JDev 12.1.3 and uses the HR DB schema. The sample can be downloaded from  Github