Professional ASP.NET 3.5 in C# and Visual Basic Part 47 pps

Evjen c08.tex V2 - 01/28/2008 2:05pm Page 416 Chapter 8: Data Management with ADO.NET Listing 8-27: Building the EmptyItemTemplate < EmptyDataTemplate > < table runat="server" style="background-color: #FFFFFF;border-collapse: collapse; border-color: #999999;border-style:none;border-width:1px;" > < tr > < td > No data was returned. < /td > < /tr > < /table > < /EmptyDataTemplate > Creating the InsertItemTemplate The last section looked at here is the InsertItemTemplate . This section allows you to define how a form should be laid out for inserting data, similar to that used in the ItemTemplate , into the data store. Listing 8-28 shows an example of the InsertItemTemplate . Listing 8-28: Building the InsertItemTemplate < InsertItemTemplate > < tr style="" > < td > < asp:Button ID="InsertButton" runat="server" CommandName="Insert" Text="Insert" / > < asp:Button ID="CancelButton" runat="server" CommandName="Cancel" Text="Clear" / > < /td > < td > < asp:TextBox ID="CustomerIDTextBox" runat="server" Text=’ < %# Bind("CustomerID") % > ’/ > < /td > < td > < asp:TextBox ID="CompanyNameTextBox" runat="server" Text=’ < %# Bind("CompanyName") % > ’/ > < /td > < td > < asp:TextBox ID="ContactNameTextBox" runat="server" Text=’ < %# Bind("ContactName") % > ’/ > < /td > < /tr > < /InsertItemTemplate > The Results After you have created an additional AlternatingItemTemplate that is the same as the ItemTemplate (but styled differently), you can then run the page. Then you will be presented with your own custom grid. An example is presented in Figure 8-9. 416 Evjen c08.tex V2 - 01/28/2008 2:05pm Page 417 Chapter 8: Data Management with ADO.NET Figure 8-9 Figure 8-10 417 Evjen c08.tex V2 - 01/28/2008 2:05pm Page 418 Chapter 8: Data Management with ADO.NET From this figure, you can see that all your defined elements are in place. The header is defined through the use of the LayoutTemplate. The items in the grid are defined through the use of the ItemTemplate. The AlternatingItemTemplate, the insert form, is defined through the use of the InsertTemplate. The page navigation is defined by the new DataPager server control. Again, the DataPager control is defined within the LayoutTemplate itself. Editing items in this template is as simple as clicking on the Edit button. This will change the view to the EditTemplate for the selected item, as illustrated in Figure 8-10. Once you enter the edit mode here, you can change any of the values within the text boxes and then click the Update button to update the data to the new values. You can also cancel out of the operation by clicking the Cancel b utton. Inserting data is as simple as filling out the form and clicking on the Insert button, as illustrated in Figure 8-11. Figure 8-11 418 Evjen c08.tex V2 - 01/28/2008 2:05pm Page 419 Chapter 8: Data Management with ADO.NET Although this example shows a grid as the output of the new ListView control, you can also structure it so that your data items are presented in any fashion you want (such as bulleted lists). Using Visual Studio for ADO.NET Tasks Earlier, this chapter covered how to construct a D ataSet and how to fill it w ith data using the Data- Adapter. Although you can always build this construction yourself, you also have the option of building data access into your ASP.NET applications using some of the wizards available from Visual Studio 2008. The following example, which is a little bit of a lengthy one, shows you how to build an ASP.NET page that displays the results from a DataSet that gets its data from two separate tables. You will discover several different wizards in Visual Studio that you can work with when using ADO.NET. Creating a Connection to the Data Source As in code, one of the first things you do when working with data is make a connection to the data source. Visual Studio provides a visual way to make connections to your data stores. In this case, you will want to make a connection to the Northwind database in SQL Server. When you open the Server Explorer, you will notice a section for data connections (see Figure 8-12). Figure 8-12 The steps to create a data connection to the Northwind database in SQL Server are straightforward. Right-click on Data Connections and choose Add Connection. You are presented with the Data Link Properties dialog box. This dialog box, by default, asks for a connection to SQL Server. If you are going to connect to a different source, such as Microsoft Access, simply click on the Provider tab and change the provider. Figure 8-13 shows the Add Connection dialog box and the settings that you need in order to connect to your local SQL Server Express Edition. If you are connecting to a SQL Server that resides on your localhost, you want to put a period (.) in the box that asks you to select or enter a server name. If you are working from a local SQL Server Express Edition file in your project (such as what is shown here in Figure 8-13), then you are going to want to useyourservernamewith \ SQLEXPRESS . Put in your login credentials for SQL Server and then select the 419 Evjen c08.tex V2 - 01/28/2008 2:05pm Page 420 Chapter 8: Data Management with ADO.NET database that you wish to make the connection to by using the drop-down list. The other option, if you are using a SQL Server Express Edition file, is to select the physical database file by using the Attach a Database File option. Figure 8-13 From this dialog box, you can also test the connection to ensure that everything works properly. If every- thing is in place, you get a confirmation stating such. Clicking OK will then cause a connection to appear in the Solution Explorer. 420 Evjen c08.tex V2 - 01/28/2008 2:05pm Page 421 Chapter 8: Data Management with ADO.NET Expanding this connection, you find a way to access the data source just as you would by using the SQL Server Enterprise Manager (see Figure 8-14). Figure 8-14 From here, you can work with the database and view information about all the tables and fields that are contained within the database. More specifically, you can view and work with Database Diagrams, Tables, Views, Stored Procedures, and Functions. 421 Evjen c08.tex V2 - 01/28/2008 2:05pm Page 422 Chapter 8: Data Management with ADO.NET After you have run through this wizard, you have a connection to the Northwind database that can be used by any components that you place on any component designer that you might be working with in your application. Working with a Dataset Designer The next step is to create a typed DataSet object in your project that pulls its data from the Northwind database. First you need to make sure that your application has an App_Code folder within the solution. Right-clicking on the folder will allow you to add a new item to the folder. From the provided dialog box, add a DataSet called CustomerOrders.xsd . You will then be presented with the message shown in Figure 8-15. Figure 8-15 This page is referred to as t he Dataset Designer. This is the design surface for any non-visual components that you incorporate within your DataSet object. Just as you can drag and drop controls onto a design surface for any Windows Forms or Web Forms application, the Dataset Designer enables you to drag and drop components onto this surface. A component does not appear visually in your applications, but a visual representation of the component sits on the design surface. Highlighting the component allows you to modify its settings and properties in the Properties window. 422 Evjen c08.tex V2 - 01/28/2008 2:05pm Page 423 Chapter 8: Data Management with ADO.NET What can you drag and drop onto this surface? In the following examples, you see how to work with TableAdapter and DataTable objects on this design surface. If you open up the Toolbox window, and click the DataSet tab, you see some additional components that can be used on this design surface. The goal of this example is to return a DataSet to the end user through an XML Web service. To accom- plish this, you have to incorporate a DataAdapter to extract the data from the data source and to populate the DataSet before passing it on. This example uses the Northwind database and the first step you need to take is to drag and drop a TableAdapter onto the D ataset design surface. Dragging and dropping a TableAdapter onto your design surface causes a wizard to appear, as shown in Figure 8-16. Figure 8-16 Because you want this DataSet to contain two DataTables — one for the Customers table and another for the Orders table — you have to go through this process twice. It is important to note that the job of the TableAdapter object is to make the connection to the specified table as well as to perform all the select, update, insert, and delete commands that are required. For this 423 Evjen c08.tex V2 - 01/28/2008 2:05pm Page 424 Chapter 8: Data Management with ADO.NET example, you simply want the TableAdapter to make the select call and then later to update any changes that are made back to the SQL Server. As you work through the wizard, you come to a screen that asks how you want to query the database (see Figure 8-17). You have three options: using SQL statements, using stored procedures that have already been created, or building brand-new stored procedures directly from this wizard. Figure 8-17 For this example, choose Use SQL statements. Selecting this option brings you to a text box where you can write your own SQL statement if you wish. The great thing about this process is that, after you create a SQL select c ommand, the TableAdapter wizard also creates the associated insert , update ,and delete c ommands for you. You also have the option of building your queries using the Query Builder. This enables you to graphically design the query yourself. If this option is selected, you can choose from a list of tables in the Northwind database. For the first TableAdapter, choose Customers. For the second TableAdapter choose Orders. You make your selection by clicking the Add button and then closing the dialog box (see Figure 8-18). 424 Evjen c08.tex V2 - 01/28/2008 2:05pm Page 425 Chapter 8: Data Management with ADO.NET Figure 8-18 Figure 8-19 425 . similar to that used in the ItemTemplate , into the data store. Listing 8-28 shows an example of the InsertItemTemplate . Listing 8-28: Building the InsertItemTemplate < InsertItemTemplate > < tr. as filling out the form and clicking on the Insert button, as illustrated in Figure 8-11. Figure 8-11 418 Evjen c08.tex V2 - 01/28/2008 2:05pm Page 419 Chapter 8: Data Management with ADO .NET Although. yourself, you also have the option of building data access into your ASP. NET applications using some of the wizards available from Visual Studio 2008. The following example, which is a little bit of