SPGridView: Adding paging to SharePoint when using custom data sources

Part 2: Extending your SPGridview with paging controls

In Part 1: Using SPGridview, adding menus, grouping and sorting I looked at how to use an SPGridView from the ground up to bind to a custom DataSet. One of the features I omitted at the time was paging:

 SPGridview showing paging controls

Jason Wang already has a good post on the subject, but I’m going to continue my example with some pretty verbose code so hopefully things will just work first time for you.  There is a gotcha – in order to display the paging tabs PagerTemplate needs to be set to null after the grid is added to the controls collection but before BindData is called; and you’ll need to give some extra consideration if you’re also using sorting.

In Part 3 by the way, I really want to cover filtering, but it’s proving tricky stuff, due to the way SPGridView is designed to process the filtering callback.  At least I understand the problem - more on that shortly.

Extending your code

Pop this code just above oGrid.DataBind():

         // Turn on paging and add event handler
        oGrid.PageSize = 3;
        oGrid.AllowPaging = true;
        oGrid.PageIndexChanging += 
            new GridViewPageEventHandler(oGrid_PageIndexChanging);
        oGrid.PagerTemplate = null;  // Must be called after Controls.Add(oGrid)

        // Recreate current sort if needed
        if (ViewState["SortDirection"] != null && ViewState["SortExpression"] != null)
            // We have an active sorting, so this need to be preserved
            oView.Sort = ViewState["SortExpression"].ToString()
                + " " + ViewState["SortDirection"].ToString();

and add the event handler:

         void oGrid_PageIndexChanging(object sender, GridViewPageEventArgs e)
            oGrid.PageIndex = e.NewPageIndex;

The extra lines around sorting are important if you enabled sorting on the list in Part 1.  Adding the paging means CreateChildControls() could now fire on a postback without a subsequent call to oGrid_Sorting().  Depending on how you’re implementing state, this could mean the list switches back to being unsorted – giving the impression of duplicating or missing out entries if you sort before you page, so to speak.