Chapter 11: Managing Content Using Grid View and Details View

Figure 11.5. The styled address book

All the styling we need is already defined in the skin file; we’d only need to define new properties if we wanted to alter the default values provided through the skin file. Save your work and view the results in the browser. Do they look like the display in Figure 11.5?

Congratulations! You’ve harnessed the power of CSS and skin files, and combined it with the flexibility of GridView to easily create a good-looking address book!

As you can see, you can style the items in the GridView by altering their font types, colors, and sizes. You can also style the column headers and apply an alternating item style to alternate rows in the table. Now, when the GridView is viewed in the browser, we see a little more room between cells, and the lines surrounding the GridView are gone.

Selecting Grid Records

We’ve already made quite a few changes to the display of our GridView. The next step will be to allow users to select one of the rows in the GridView so they can view more information about the selected employee.

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Selecting Grid Records

There are several types of columns that we can create in a GridView in addition to the BoundField columns we’ve already seen. For instance, we could create a ButtonField column, which displays a button in each row. The complete set of column controls and their descriptions are listed here:

BoundField

As you’ve seen, the BoundField provides flexibility in presentation by allowing you to specify which columns will appear within the GridView. When the grid enters edit mode, this field renders itself as an editable text box, as we’ll see later.

ButtonField

Use the ButtonField to display a clickable button for each row within the GridView. When clicked, the button triggers a configurable event that you can handle within your code to respond to the user’s action. The possible event types that a button can trigger are: Cancel, Delete, Edit, Select, and

Update.

CheckBoxField

The CheckBoxField displays a checkbox in each row, allowing you to easily present Boolean data in the display.

CommandField

The CommandField column automatically generates a ButtonField in your grid. The actions performed by these buttons depend on the grid’s current state. For example, if CommandField is set to generate Edit buttons, it will display an Edit button when the grid is in non-editable mode, and will display

Update and Cancel buttons when the grid is being edited.

HyperLinkField

Use the HyperLinkField to display a clickable link within the GridView. This link simply acts as a hyperlink to a URL; it raises no server-side events.

ImageField

This control displays an image inside your grid.

TemplateField

Use the TemplateField to display markup within the GridView.

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Chapter 11: Managing Content Using Grid View and Details View

Figure 11.6. Adding a new GridView column

If you’re using Visual Web Developer, you can quickly and easily add a new column to your table in Design View. Click the GridView’s smart tag, and click the Add New Column... item, as shown in Figure 11.6.

In the dialog that appears, change the field type to ButtonField, the command name to Select, and set the Text field to Select, so the dialog appears as it does in Figure 11.7.

Figure 11.7. Adding a new field

After clicking OK, your brand new column shows up in Design View. If you switch to Source View, you can see it there, too:

File: AddressBook.aspx (excerpt)

<asp:GridView ID="grid" runat="server" AutoGenerateColumns="false">

<Columns>

<asp:BoundField DataField="Name" HeaderText="Name" /> <asp:BoundField DataField="City" HeaderText="City" />

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Selecting Grid Records

<asp:BoundField DataField="MobilePhone" HeaderText="Mobile Phone" />

<asp:ButtonField CommandName="Select" Text="Select" />

</Columns>

</asp:GridView>

If you execute the project now, and click the new button, the row will become highlighted, as Figure 11.8 indicates. Notice that you didn’t write any code to implement this feature? We’re relying on the functionality provided by the ButtonField control when it’s CommandName property is set to Select, and the style settings you set earlier, to produce this functionality.

Figure 11.8. Highlighting the selected field in the Address Book

We usually want extra work—in addition to the row highlight—to be performed when a user selects a row in the address book. When the Select button is pressed, the GridView fires the SelectedIndexChanged event, which we handle if we need to do any further processing. We can generate the GridView’s SelectedIndexChanged event handler simply by double-clicking the GridView in the Visual Web Developer designer.

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Generating Default Event Handlers

Double-clicking a control in the designer causes Visual Web Developer to generate the handler of the control’s default event. The default event of the GridView is SelectedIndexChanged, which explains why it’s so easy to generate its signature. Remember that you can use the Properties window to have Visual Web Developer generate handlers for other events—just click the lightning icon in the Properties window, then double-click on any of the listed events.

Before we handle the SelectedIndexChanged event, let’s add just below the GridView control in AddressBook.aspx a label that we can use to display some details of the selected record. You can use Visual Web Developer’s designer to add the control, or you can write the code manually:

File: AddressBook.aspx (excerpt)

</asp:GridView>

<br />

<asp:Label ID="detailsLabel" runat="server" />

</asp:Content>

Now, generate the SelectedIndexChanged event handler by double-clicking the GridView control in Design View, then update the event handler to display a short message about the selected record:

Visual Basic

File: AddressBook.aspx.vb (excerpt)

Protected Sub grid_SelectedIndexChanged(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles grid.SelectedIndexChanged

'Obtain the index of the selected row Dim selectedRowIndex As Integer selectedRowIndex = grid.SelectedIndex

'Read the name from the grid

Dim row As GridViewRow = grid.Rows(selectedRowIndex) Dim name As String = row.Cells(0).Text

' Update the details label

detailsLabel.Text = "You selected " & name & "." End Sub

C# File: AddressBook.aspx.cs (excerpt)

protected void grid_SelectedIndexChanged(object sender, EventArgs e)

{

// Obtain the index of the selected row int selectedRowIndex;

selectedRowIndex = grid.SelectedIndex;

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