Iterate through all items on all pages

[Kris]

I am doing a custom export to excel where I load the grid, say 10 items on the first page, 3 pages long. The user then filters the grid using the built in filter column headers. That limits the grid to 14 items in 2 pages. The user clicks my export button where the following gets executed:

        /// <summary>
        /// Exports data in grid to excel
        /// </summary>
        public void Export()
        {
            //rgdProjectWorksheets.ExportSettings.ExportOnlyData = true;
            //rgdProjectWorksheets.ExportSettings.IgnorePaging = true;
            //rgdProjectWorksheets.MasterTableView.ExportToExcel();

            PWDetailAccess pwa = new PWDetailAccess();
            DataTable dt = pwa.GetFlatExportData(Convert.ToInt32(Session[ApplicationConstants.SessionVariables.OrganizationID].ToString()));

            List<int> idlist = GetVisibleIDList();

            HttpContext context = HttpContext.Current;
            context.Response.Clear();
            foreach (DataColumn column in dt.Columns)
            {
                context.Response.Write(column.ColumnName + ",");
            }
            context.Response.Write(Environment.NewLine);
            foreach (DataRow row in dt.Rows)
            {
                if (!idlist.Contains(Convert.ToInt32(row[PWDetailsSchema.ID].ToString())))
                    continue;
                for (int i = 0; i < dt.Columns.Count; i++)
                {
                    context.Response.Write(row[i].ToString().Replace(",", string.Empty) + ",");
                }
                context.Response.Write(Environment.NewLine);
            }

            context.Response.ContentType = "text/csv";
            context.Response.AppendHeader("Content-Disposition", "attachment; filename=SA_FlatExport.csv");
            context.Response.End();
        }

        private List<int> GetVisibleIDList()
        {
            List<int> idlist = new List<int>();
            for (int i = 0; i < rgdProjectWorksheets.MasterTableView.Items.Count; i++)
            {
                if (rgdProjectWorksheets.Items[i].Visible == true)
                    idlist.Add(Convert.ToInt32(rgdProjectWorksheets.Items[i][PWDetailsSchema.ID].Text));
            }
            return idlist;
        }

I compare my full custom datatable with the items in the grid to decide which items in my datatable I will include in the export. This works great on a grid with no paging. The problem arises when I have more than one page. It appears that the count in
rgdProjectWorksheets.MasterTableView.Items only holds the items on the current page. How do I iterate through all the items in all pages?


I've tried running the GetVisibleIDList method in the PreRender event (as this post suggests), but that does not seem to be working.
Any help would be much appreciated.
Thanks
Kris

[Veli]

Hello Kris,

As you have observed correctly, RadGrid keeps only the current page of data when paging is enabled. It never requests or processes any other data than the current page. You have access to whatever data RadGrid is bound only. This is why, with paging, you cannot get data in other pages.

If you need to bind RadGrid to all the data in all pages, you need to disable paging (set AllowPaging="false"), Rebind, and then iterate over your items. Still, if you have access to the data, iterating over all your data items yourself may be quicker than disabling paging, binding the grid and then re-enabling paging and rebinding.

Best wishes,
Veli
the Telerik team

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[Kris]

Ok, thanks for the reply. It would be nice if it cached all the records somewhere to prevent the re-binding of the grid, but this will do for now.

One note though, when re-binding, you need to rebind the MasterTableView, not the grid object itself.

For example, this doesn't work

            rgdProjectWorksheets.AllowPaging = false;
            rgdProjectWorksheets.Rebind();

but this does

            rgdProjectWorksheets.MasterTableView.AllowPaging = false;
            rgdProjectWorksheets.MasterTableView.Rebind();

[Veli]

Hello Kris,

RadGrid does not cache any data it is bound two. There are many reasons for this, 2 of the most important being:

1. Where to cache? Caching in the ViewState is a performance nightmare. Caching in Session can be problemmatic for many users and large data sets.

2. How to provide concurrency? What happens when a piece of data is updated outside of the grid, but the grid keeps rebinding to stale data from the cache?

Still, if you believe caching data suits your needs, it can be implemented relatively easily by the developer, so I believe this is more or less out of scope for RadGrid.

As for setting AllowPaging from RadGrid's object, I do not seem to observe any differences. Both approaches seem to work OK. Attaching sample page used for testing.

Sincerely yours,
Veli
the Telerik team

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[Chanan Zass]

Dim pageCount As Integer = RadGrid1.MasterTableView.PageCount
        Dim i As Integer = 0
        While i < pageCount
            RadGrid1.CurrentPageIndex = i
            RadGrid1.Rebind()

            For Each r As GridDataItem In RadGrid1.MasterTableView.Items
                  ' do something
            Next
            i += 1
        End While

[Justin]

Thank you so much Kris for your post.  I was binding to the radgrid, not the mastertable.  Your post finally got me over the hump I've been stuck on since yesterday afternoon.

[w]

May I check with you, the latest RadGrid Q3 2014 version still not cache all the data (ignore paging) at client side?

[Konstantin Dikov]

Hello,

For the same reasons that were pointed out in the previous posts in this thread, RadGrid does not have server-side caching.

Nevertheless, if you are using client-side binding, you can take advantage of the client-side caching functionality, by setting the ClientSettings.DataBinding.EnableCaching property to true. You can find additional information on this matter in the following help article, section Client-Side Caching:

• Client-side Binding

Best Regards,
Konstantin Dikov
Telerik