Working with Data in ASP.NET 2.0 Handling BLL and DAL Level Exceptions in an ASP.NET Page
Working with data from an ASP.NET web application using a tiered application architecture involves the following three general steps:
1. Determine what method of the Business Logic Layer needs to be invoked and what parameter values to pass it. The parameter values can be hard coded, programmatically assigned, or inputs entered by the user.
2. Invoke the method.
3. Process the results. When calling a BLL method that returns data, this may involve binding the data to a data Web control. For BLL methods that modify data, this may include performing some action based on a return value or gracefully handling any exception that arose in Step 2.
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Working with Data in ASP.NET 2.0 - Handling BLL and DALLevel Exceptions
In the Overview of Editing and Deleting Data in the DataList tutorial, we created a DataList that offered simple editing and deleting capabilities. While fully functional, it was hardly userfriendly, as any error that occurred during the editing or deleting process resulted in an unhandled exception. For example, omitting the product’s name or, when editing a product, entering a price value of “Very affordable!”, throws an exception. Since this exception is not caught in code, it bubbles up to the ASP.NET runtime, which then displays the exception’s details in the web page. As we saw in the Handling BLLand DALLevel Exceptions in an ASP.NET Page tutorial, if an exception is raised from the depths of the Business Logic or Data Access Layers, the exception details are returned to the ObjectDataSource and then to the GridView. We saw how to gracefully handle these exceptions by creating Updated or RowUpdated event handlers for the ObjectDataSource or GridView, checking for an exception, and then indicating that the exception was handled.
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