Part V: Building Community Applications in Visual Studio .NET

Printer Code 39 in Visual Studio .NET Part V: Building Community Applications

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This </ItemTemplate> tag marks the end of the item template for the inner Repeater control, which was started in Line 7 This </asp:Repeater> tag marks the end of the inner Repeater control It pairs with the <Repeater> tag in Line 6 This </ItemTemplate> tag marks the end of the item template for the outer Repeater control, started in Line 5 This </asp:Repeater> tag marks the end of the outer Repeater control It matches up with the <Repeater> tag in Line 4 This line marks the end of the HTML table started in Line 3

The code-behind file for the Forum Home page handles the details of retrieving the forum and topic information from the database Then it binds the outer Repeater control to the list of forums Finally, each time an item is bound for the outer Repeater control, this process binds the inner Repeater control and displays topics for the current forum Listings 10-4 and 10-5 show the C# and Visual Basic versions of this codebehind file

Listing 10-4:

The code-behind file for the home page (C# version)

System; SystemData; SystemConfiguration; SystemCollections; SystemWeb; SystemWebSecurity; SystemWebUI; SystemWebUIWebControls; SystemWebUIWebControlsWebParts; SystemWebUIHtmlControls; SystemWebConfiguration; SystemDataSqlClient;

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public partial class _Default : SystemWebUIPage { DataSet ds; protected void Page_Load(object sender,

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EventArgs e) { string con = WebConfigurationManager 5 ConnectionStrings[ ForumConnectionString ] ConnectionString; ds = new DataSet();

// fill the Forums table 7 string sel = SELECT [forumid], [name] + FROM Forums + ORDER BY [name] ; SqlDataAdapter da = new SqlDataAdapter(sel, con); daFill(ds, Forums ); // fill the Topics table sel = SELECT [forumid], [topicid], + [name], [description] + FROM Topics + ORDER BY [name] ; da = new SqlDataAdapter(sel, con); daFill(ds, Topics );

// bind the Forum repeater 9 ForumRepeaterDataSource = dsTables[ Forums ] DefaultView; ForumRepeaterDataBind(); } public void ForumRepeater_ItemDataBound( Object sender, RepeaterItemEventArgs e) { Repeater r = ((Repeater)eItem FindControl( TopicRepeater )); DataRowView drv = (DataRowView)eItemDataItem; string forumid = drv[ forumid ]ToString(); DataView dv = dsTables[ Topics ]DefaultView; dvRowFilter = forumid= + forumid; rDataSource = dv; rDataBind(); } }

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Here s a set of 14 explanations, matched to the 14 key lines of this listing:

The code-behind file needs access to the SystemWeb Configuration namespace because it uses the WebConfigurationManager class to retrieve the database connection string from the webconfig file The SystemDataSqlClient namespace is required to use ADONET classes such as DataSet, SqlConnection, and SqlCommand This line defines a class instance variable of type DataSet That way, the dataset will be available to both of the methods in the code-behind file The Page_Load method executes when the page loads It fills the dataset with data retrieved from the Forums and Topics tables; it also sets up data binding for the ForumRepeater control and calls that control s DataBind method, which completes the binding This line retrieves the connection string from the webconfig file This statement creates an empty dataset object and assigns it to the ds variable These lines create a table in the ds dataset named Forums by a) creating a data adapter that retrieves rows from the Forums table and b) calling the data adapter s Fill method These lines create a second table in the dataset (named Topics) by creating a data adapter (which retrieves data from this new Topics table) and calling the data adapter s Fill method These lines set the data source for the ForumRepeater control to the Forums table in the dataset, and then call the DataBind method to bind the Repeater control to its data This method is called each time an item is bound to the outer Repeater It binds the inner Repeater control to the topics that are associated with the forum represented by the item The e argument includes a property named Item that represents the item being bound This statement calls that item s FindControl method to find the Repeater control named TopicRepeater That particular Repeater is then assigned to the variable named r so it can be used later These lines retrieve the id of the forum represented by the current Repeater item First, eItemDataItem is used to retrieve a DataRowView object that lets you access the individual data fields for the Repeater item Then the forumid field is retrieved and saved in a local variable named forumid

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