Part IV: Building Back-End Applications in Visual Studio .NET

Creation Code-39 in Visual Studio .NET Part IV: Building Back-End Applications

An HTML table displays the GridView and FormView controls side by side The table consists of a single row with two columns, one for the GridView, the other for the FormView The GridView control displays the products from the Products table so the user can select a product to update or delete The data source is SqlDataSource1, and paging is enabled As a result, only ten product rows are displayed at a time The first column defined for the GridView control displays the productid field from the data source The second column displays the name field The third column is a command field that displays a Select link When the user clicks this link, the indicated product is selected which (in turn) displays the detail data for the selected product in the FormView control The first data source, named SqlDataSource1, provides the data displayed by the GridView control Its Select statement simply selects all rows from the Products table The FormView control displays the detail data for the product selected by the GridView1 control Note that the connection to the GridView1 control isn t specified in the FormView control itself Instead, the data source that the FormView control is bound to (SqlDataSource2) handles this relationship The FormView control uses templates to specify how its data is to be displayed The first of these is the EmptyDataTemplate used when the data source has no data in which case, the FormView control displays this instruction: Please select a product In addition, a link lets the user place the FormView control in Insert mode by specifying New for the CommandName attribute The ItemTemplate displays the data for the row selected by the data source This template consists of several labels and text fields that display product data; the text boxes are all marked read-only so the user can t change their contents (Note that I could have used labels instead of text boxes to display the data in the item template Then I wouldn t have to use the ReadOnly attribute I chose to use read-only text fields instead because I wanted the bordered look provided by the TextBox control)

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The first text box in the item template displays the product ID Note how an ASPNET 20 binding expression is used to bind the Text property of the text box to the productid field of the data source The new Eval method provides a simple way to provide one-way binding for display-only fields The next TextBox control displays the category ID Here, the Bind method is used instead of the Eval method to provide two-way (input and output) data binding This text box displays the product name This text box displays the shorttext field of the data source Note that the MultiLine attribute is specified for the text box so the user can enter more than one line of text This text box displays the longtext field again, using the MultiLine attribute so the user can enter more than one line of text This text box binds to the price field of the data source In this case, a format string is used along with the Bind method to apply currency formatting to the price This text box displays the thumbnail field This text box displays the image field This link button, which appears at the bottom of the item template, allows the user to edit the product data Note that the CommandName attribute specifies Edit as the command name The FormView control displays the EditItemTemplate, defined in line 23, when the user clicks this button This link button lets the user delete the product Its CommandName attribute specifies Delete as the command name As a result, the product row is automatically deleted when the user clicks this button The New link button displays the InsertItem template, defined starting at line 34 Then the user can enter the data for a new product The EditItemTemplate defines the data that s displayed when the user clicks the Edit link, placing the FormView control in Edit mode As you can see, the contents of this template are very similar to the contents of the item template

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