MSDN Magazine - April 2008 - (Page 40)

It turns out that selecting the right page of data remains the problem of the data-bound control—in this case, the ListView. Just as with other “view” controls in ASP.NET, the ListView control relies on external code for paging. If data is bound through the data source property, then user code should provide for the paged data. Otherwise, if data is bound through a data source control, you should configure the data source control properly to support paging. Both the LinqDataSource and ObjectDataSource controls offer built-in paging capabilities. The LinqDataSource has the AutoPage property for enabling or disabling default paging. For hierarchical data, you also need to ensure that the LINQ data context has proper load options set. The programming interface of the LinqDataSource doesn’t have properties for setting the LoadOptions property on the data context object. However, by handling the ContextCreated event, you can access the newly created data context and configure it as you like: void LinqDataSource1_ContextCreated( object sender, LinqDataSourceStatusEventArgs e) { // Get a reference to the data context DataContext db = e.Result as DataContext; if (db != null) { DataLoadOptions opt = new DataLoadOptions(); opt.LoadWith (c => c.Orders); opt.LoadWith (o => o.Employee); opt.LoadWith (o => o.Order_Details); db.LoadOptions = opt; } As an alternative to this action, you can use the ObjectDataSource control for providing data and implementing any paging logic. Then, in the business object you can either use LINQ to SQL or plain ADO.NET for data access. A snag I ran into while using DataPager and ListView together is worth mentioning, though. I initially had a content page with ListView and DataPager hosted in the same content placeholder. I referenced the ListView control in the DataPager using the PagedControlID property, as shown in the following. It worked just fine: } Next, I moved the DataPager to another content area in the same master. And all of a sudden, the DataPager was unable to communicate with the ListView control. The problem lies with the algorithm used by the DataPager control to locate the paged control. This algorithm doesn’t work if the two controls are hosted by different naming containers. To work around the issue, you need to identify the paged control using its full, unique ID (that includes naming container information). Unfortunately, you can’t easily set this information declaratively. 40 msdnmagazine Cutting Edge http://msdn.primalscript.com http://msdn.primalscript.com

Table of Contents Feed for the Digital Edition of MSDN Magazine - April 2008

MSDN Magazine - April 2008 Contents Toolbox CLR Inside Out Basic Instincts Cutting Edge Foundations Test Run Service Station Windows with C++ Going Places { End Bracket }

MSDN Magazine - April 2008

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