p:dataTable selections are lost after paginating a LazyDataModel

Question

My problem is that after I\'ve selected a few items on the 1st page, if I paginate to another page and come back, my initial selections are not shown. I\'ve tried to impleme

Answer 1

This is because when SelectionFeature is decoded a new list is created.

And if table.getRowData(rowKeys[i]) (related to your LazyDataModel implementation) returns null your old selectıons in the previous page are gone.may try to solve it by changing your LazyDataModel implementation I didn't try these but take a look at this and this

Had the same problem and I think this solution is easier if you have a lot of different tables implementing LazyDataModel.

This is what I did: check if it is lazy first then add currently selected rows to the selectionList.

For primefaces 4.0

1)Override DataTableRenderer

In faces-config.xml

   
       org.primefaces.component
       org.primefaces.component.DataTableRenderer
       com.package.LazyDataTableRenderer
   

And

public class LazyDataTableRenderer extends DataTableRenderer {
static Map FEATURES;

    static {
        FEATURES = new HashMap();
        FEATURES.put(DataTableFeatureKey.DRAGGABLE_COLUMNS, new DraggableColumnsFeature());
        FEATURES.put(DataTableFeatureKey.FILTER, new FilterFeature());
        FEATURES.put(DataTableFeatureKey.PAGE, new PageFeature());
        FEATURES.put(DataTableFeatureKey.SORT, new SortFeature());
        FEATURES.put(DataTableFeatureKey.RESIZABLE_COLUMNS, new ResizableColumnsFeature());
        FEATURES.put(DataTableFeatureKey.SELECT, new LazySelectionFeature());
        FEATURES.put(DataTableFeatureKey.ROW_EDIT, new RowEditFeature());
        FEATURES.put(DataTableFeatureKey.CELL_EDIT, new CellEditFeature());
        FEATURES.put(DataTableFeatureKey.ROW_EXPAND, new RowExpandFeature());
        FEATURES.put(DataTableFeatureKey.SCROLL, new ScrollFeature());
    }

    @Override
    public void decode(FacesContext context, UIComponent component) {
        DataTable table = (DataTable) component;

        for(Iterator it = FEATURES.values().iterator(); it.hasNext();) {
            DataTableFeature feature = it.next();

            if(feature.shouldDecode(context, table)) {
                feature.decode(context, table);
            }
        }

        decodeBehaviors(context, component);        
    }
}

2)Override SelectionFeature's decode

Updated: edited to allow deselecting

public class LazySelectionFeature extends org.primefaces.component.datatable.feature.SelectionFeature{

    @Override
    public void decode(FacesContext context, DataTable table) {
        String clientId = table.getClientId(context);
        Map params = context.getExternalContext().getRequestParameterMap();

        String selection = params.get(clientId + "_selection");

        if(table.isSingleSelectionMode())
            decodeSingleSelection(table, selection);
        else
            decodeMultipleSelection(context, table, selection);
    }

    void decodeSingleSelection(DataTable table, String selection) {
            if(ComponentUtils.isValueBlank(selection))
                table.setSelection(null);
            else
                table.setSelection(table.getRowData(selection));
        }

    void decodeMultipleSelection(FacesContext context, DataTable table, String selection) {
        Class clazz = table.getValueExpression("selection").getType(context.getELContext());
        boolean isArray = clazz.isArray();

        if(!isArray && !List.class.isAssignableFrom(clazz)) {
            throw new FacesException("Multiple selection reference must be an Array or a List for datatable " + table.getClientId());
        }

        if(ComponentUtils.isValueBlank(selection)) {
            if(isArray) {
                table.setSelection(Array.newInstance(clazz.getComponentType(), 0));
            }
            else {
                table.setSelection(new ArrayList