Figure 17-4
The Object Relational Designer (O/R Designer) then launches so that you can visually edit the databases and tables you want to use. Open the Server Explorer window, and connect to the pubs sample database. Drag and drop the publisher and title tables onto the design surface of DataClasses.dbml (see Figure 17-5).
Figure 17-5
Save the DataClasses.dbml file by pressing Ctrl+S. When you save the file, Visual Studio 2008 persists out .NET classes that represent the entities and database relationships that you have just added. For each LINQ to SQL designer file you add to your solution, a custom DataContext class is generated. It is the main object that you use to manipulate the table. In this example, the DataContext class is named DataClassesDataContext.
Be sure to save DataClasses.dbml before proceeding.
Data Binding Using the GridView Control
To display the records from a table, you can use the GridView control, which displays the values of a data source in a table where each column represents a field and each row represents a record. Drag the GridView control from the Toolbox and drop it onto the design surface of Default.aspx. In the SmartTag of the GridView control, select <New data source…> in the Choose Data Source dropdown list (see Figure 17-6).
Figure 17-6
In the Data Source Configuration Wizard (see Figure 17-7), select LINQ and click OK. Use the default name of LinqDataSource1. Click OK.
Figure 17-7
For those of you familiar with the various data source controls (such as SqlDataSource and ObjectDataSource) in ASP.NET 2.0, the LinqDataSource control works much like them. What is special about the LinqDataSourcecontrol is that instead of binding directly to a database (as with the SqlDataSource), it binds to a LINQ-enabled data model. The beauty of this is that you need not write the various complex SQL queries (such as insert, delete, and modify) to use it. Instead, you just need to specify the data model you are working with, and the type of operations you want to perform on it (such as delete, insert, or update) and then the control takes care of performing those operations by itself.
The DataClassesDataContext object that you generated earlier is automatically selected for you (see Figure 17-8). Click Next.
Figure 17-8
Select the titles table, and click the * checkbox to select all fields (see Figure 17-9).
Figure 17-9
Click the Advanced button and check all the checkboxes. Click OK (see Figure 17-10) and then click Finish.
Figure 17-10
Switch to the source view of Default.aspx page, and observe the <asp:LinqDataSource> element:
<asp:LinqDataSource
ID='LinqDataSource1' runat='server'
ContextTypeName='DataClassesDataContext'
EnableDelete='True'
EnableInsert='True'
EnableUpdate='True'
TableName='titles'>
</asp:LinqDataSource>
Select the GridView control's SmartTag, and check the five checkboxes (see Figure 17- 11).
Figure 17-11
This makes the GridView look like Figure 17-12. The column names are now clickable and that new column containing Edit, Delete, and Select is added to the GridView control. Also, paging is now enabled (located at the bottom of the GridView control).
Figure 17-12
Click the Auto Format link in the SmartTag of the GridView control, and select the Sand and Sky scheme.
The GridView control contains all the fields of the titles table, but there are some that you don't really need. So select the notes column, and remove it by choosing Remove Column from GridView Tasks (see Figure 17-13). Delete the advance, royalty, and ytd_sales columns as well.
Figure 17-13
The GridView control should now look like Figure 17-14.
Figure 17-14
Now, to debug the application, press F5. You are asked to modify the Web.config file for debugging; click OK. You also are prompted that script debugging is disabled in Internet Explorer; click Yes to continue debugging.
Figure 17-15 shows the GridView control displaying the rows in the titles table. You can sort the rows by clicking on the column headers, and edit and delete records.
Figure 17-15
Displaying Publisher's Name
As Figure 17-15 shows, the publisher's ID appears in the GridView control under the pub_id field. It would be helpful to the user if the publisher's name displayed instead of its ID. To do that, switch to the source view of Default.aspx and within the <asp:GridView> element, replace the following element:
<asp:BoundField
DataField='pub_id'
