Sorting is not working in datatable in PrimeFaces?

Question

Sorting is not working in datatable in PrimeFaces. Please suggest.

See below my .xhtml file

Answer 1

The primefaces backing bean (ViewScoped!) must hold it's own List of rows. So, e.g., if you query the database every time you request the p:dataTable:value, sorting will not work.

Solution: Collect the List from the Database and keep it in a local List variable in the backing bean.

public List getDataTable() {
    if (tableDataList == null)
        tableDataList = loadListOnce();
    return tableDataList;
}