Building A SPGridView Control – Part 1: Introducing the SPGridView

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The SPGridView is one of the most ubiquitous controls used in SharePoint. Every single list in SharePoint (and as we all know there’s lots of those!) uses the SPGridView to display its data in neatly formatted rows. We’re able to sort its data, filter it and click on an item to choose from any options available on that item, amongst other options.

When we build a custom Web Part, we suddenly find ourselves without all that SharePoint goodness. The standard GridView (found in System.Web.UI.WebControls) gives us all the abilities we look for, but it takes a lot of effort to make it look like a SharePoint grid. Luckily, there’s the SPGridView (found in Microsoft.SharePoint.WebControls). It inherits from the GridView so can do whatever the GridView can do. But it does it in style – SharePoint style.

Getting the SPGridView to look and perform just like the standard SharePoint grids does require some work but with the right choices we can limit this to the absolute minimum. Let’s get started.

To host our SPGridView control we’ll need a basic Web Part skeleton which you can find as part of the files attached to this post. There’s nothing special about it, it serves simply as a place to drop our control. You can of course also use the standard Web Part-User Control pattern.

We’ll use a standard DataTable as the data source for our SPGridView which we’ll bind to an ObjectDataSource (found in System.Web.UI.WebControls). I’ve found the ObjectDataSource easier to use than a DataSet (for example, sorting and paging require no additional code whatsoever) and I haven’t quite had time to dive into using the SPDataSource. Once I have, I’ll be sure to update this post as needed.

Our SelectData method will look as follows:

public DataTable SelectData()
{
   DataTable dataSource = new DataTable();

   dataSource.Columns.Add("ID");
   dataSource.Columns.Add("Name");
   dataSource.Columns.Add("Region");
   dataSource.Columns.Add("Total Sales");

   dataSource.Rows.Add(1, "J. Smith", "Europe", 10000);
   dataSource.Rows.Add(2, "J. Smith", "North America", 15000);
   dataSource.Rows.Add(3, "J. Smith", "Asia", 5000);
   dataSource.Rows.Add(4, "S. Jones", "Europe", 7000);
   dataSource.Rows.Add(5, "S. Jones", "North America", 30000);
   dataSource.Rows.Add(6, "S. Jones", "Asia", 8700);
   dataSource.Rows.Add(7, "W. Nguyen", "Europe", 3000);
   dataSource.Rows.Add(8, "W. Nguyen", "North America", 50000);
   dataSource.Rows.Add(9, "W. Nguyen", "Asia", 25000);

   return dataSource;
}

We’ll be initializing our objects in the CreateChildControls method:

protected sealed override void CreateChildControls()
{
   const string GRIDID = "grid";
   const string DATASOURCEID = "gridDS";

   gridDS = new ObjectDataSource();
   gridDS.ID = DATASOURCEID;
   gridDS.SelectMethod = "SelectData";
   gridDS.TypeName = this.GetType().AssemblyQualifiedName;
   gridDS.ObjectCreating +=
   new ObjectDataSourceObjectEventHandler(gridDS_ObjectCreating);
   this.Controls.Add(gridDS);

   grid = new SPGridView();
   grid.ID = GRIDID;
   grid.DataSourceID = gridDS.ID;
   grid.AutoGenerateColumns = false;

   // Paging
   grid.AllowPaging = true;
   grid.PageSize = 5;

   // Sorting
   grid.AllowSorting = true;

   this.Controls.Add(grid);

   SPGridViewPager pager = new SPGridViewPager();
   pager.GridViewId = grid.ID;

   this.Controls.Add(pager);
}

There are a few things to note here. One, I am setting the DataSourceID property of the SPGridView control instead of the DataSource property. This is required to enable filtering later on. I’ve no idea why, but I am grateful to Robert Fridén for figuring this out.

Second, I am setting the TypeName of the ObjectDataSource to the ASPGridView control itself. This allows us to access all the properties of the ASPGridView in our GetDataSource method which will prove useful when we’ll perform data binding against a SPList. It does introduce a problem where the ObjectDataSource “cannot find a non-generic method ‘GetDataSource’ …”. It also introduces a problem with the ObjectDataSource creating a fresh instance of our ASPGridView control, which resets our sorely-needed properties. Fortunately, the fix is surprisingly simple.

When ObjectDataSource creates an instance of the type specified through its TypeName property it raises the ObjectCreating event. In this event, we simply assign our current object instance to the object instance the ObjectDataSource is expecting to use:

private void gridDS_ObjectCreating(object sender, ObjectDataSourceEventArgs e)
{
   e.ObjectInstance = this;
}

Finally, most blogs will tell you that you need to set the PagerTemplate property of the SPGridView to null. I am using the SPGridViewPager here so we don’t need to. In addition, we get the actual paging behavior used by SharePoint without having to implement any of the Paging events.

If you have read other articles which describe the SPGridView you’ll have noticed that I am not creating the columns for the SPGridView here. I used to until I discovered a strange problem when using more than one ASPGridView on the same page. When I’d set the Visible property of one of the controls to False, the headers of the other control would disappear! To prevent this, I’m generating my columns and performing data binding in the Render method:

protected sealed override void Render(HtmlTextWriter writer)
{
   GenerateColumns();
   grid.DataBind();
   base.Render(writer);
}

And that’s all we need to create a simple SPGridView that supports paging and sorting out-of-the-box.

You can see our progress so far here. Also, you can download the solution I created for this part of the series here. The solution uses the WSPBuilder. To install the demo Web Part, simply build the solution and run the Setup.exe file. Then activate the newly created feature in your SharePoint site and add the Web Part to the page.

I hope this post was useful to you. If so, let me know. If you find that there are things missing, I’d love to hear from you, too.

Source:reversealchemy.net