How to send current page number in Ajax request

I am using jQuery DataTable to display huge amount of data in a table. I am getting data page wise on Ajax request like this:

var pageNo = 1;
$('#propertyTable').dataTable( {
    "processing": true,
    "serverSide": true,
    "ajax": "${contextPath}/admin/getNextPageData/"+pageNo+"/"+10,
    "columns": [
        { "data": "propertyId" },
        { "data": "propertyname" },
        { "data": "propertyType" },
        { "data": "hotProperties" },
        { "data": "address" },
        { "data": "state" },
        { "data": "beds" },
        { "data": "city" },
        { "data": "zipCode" }
    ],
    "fnDrawCallback": function () {
        pageNo = this.fnPagingInfo().iPage+1;
        alert(pageNo); // this alerts correct page
     }
} );

and here is the spring controller:

@RequestMapping(value="/getNextPageData/{pageNo}/{propertyPerPage}")
public @ResponseBody PropertyDatatableDto getNextPageData(@PathVariable Integer pageNo, @PathVariable Integer propertyPerPage) {
    System.out.println("called");
    System.out.println(pageNo); // this always prints 1, what i need is current pageNo here


    PropertyDatatableDto datatableDto = new PropertyDatatableDto();
    //datatableDto.setDraw(1);
    datatableDto.setRecordsTotal(100);
    datatableDto.setRecordsFiltered(100);
    datatableDto.setData(adminService.getAllPropertyList());
    return datatableDto;
}

The problem is that when I change page in table it alerts correct pageNo on page (in JavaScript), but in spring controller I am always getting the initial value assigned to the variable pageNo and not the current page number.

How do I pass pageNo dynamically to spring controller? Any help is appreciated.

Edit:

I updated JavaScript like this:

    var oSettings = $('#propertyTable').dataTable().fnSettings();
    var currentPageIndex = Math.ceil(oSettings._iDisplayStart / oSettings._iDisplayLength) + 1; 

$('#propertyTable').dataTable({
    "processing": true,
    "serverSide": true,
    "ajax": "${contextPath}/admin/getNextPageData/"+currentPageIndex+"/"+10,
    "columns": [
        { "data": "propertyId" },
        { "data": "propertyname" },
        { "data": "propertyType" },
        { "data": "hotProperties" },
        { "data": "address" },
        { "data": "state" },
        { "data": "beds" },
        { "data": "city" },
        { "data": "zipCode" }
    ]
});

But it’s giving me an error:

DataTables warning: table id=propertyTable – Cannot reinitialise DataTable.

Answer

DataTables already sends parameters start and length in the request that you can use to calculate page number, see Server-side processing.

If you still need to have the URL structure with the page number, you can use the code below:

"ajax": {
   "data": function(){
      var info = $('#propertyTable').DataTable().page.info();

      $('#propertyTable').DataTable().ajax.url(
          "${contextPath}/admin/getNextPageData/"+(info.page + 1)+"/"+10
      );
   }
},