Build Your Own ASP.NET 3.5 Website Using C# & VB (87 page)

Figure 12.14. Testing the query generated for our data source

the DetailsView to behave. Locate the DetailsView control and set the properties

as outlined in
Table 12.2.

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Table 12.2. Properties to Set for the DetailsView Control

Property

Value

AutoGenerateDeleteButton

True

AutoGenerateEditButton

True

AutoGenerateInsertButton

True

AllowPaging

False

DataSourceID

employeeDataSource

DataKeyNames

EmployeeID

If you’re using
Design
view, make sure you choose
Yes
when you’re asked about recreating the DetailsView rows and data keys. If you’re not using
Design
view, set the columns as shown here:

Dorknozzle\VB\07_AddressBook.aspx
(excerpt)

InsertVisible="False" ReadOnly="True"

SortExpression="EmployeeID" />

HeaderText="DepartmentID" SortExpression="DepartmentID" />

SortExpression="Name" />

SortExpression="Username" />

SortExpression="Password" />

SortExpression="Address" />

SortExpression="City" />

SortExpression="MobilePhone" />

SortExpression="State" />

SortExpression="Zip" />

SortExpression="HomePhone" />

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SortExpression="Extension" />

You’re ready! Execute the project, and enjoy the new functionality that you implemented without writing a single line of code. Take it for a quick spin to ensure that the features for editing and deleting users are perfectly functional.

Right now, if you select an employee from the list, you’ll see the page shown in

Figure 12.15
.

Figure 12.15. Adding a new employee

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Build Your Own ASP.NET 3.5 Web Site Using C# & VB

When you click on
New
to add a new employee, the form becomes editable, allowing

you to create a new employee record.

Adding Users the Easy Way

If you want to be able to use this form to add new employees to the database, the

easiest way to do so is to leave in all the required columns; otherwise, you’ll get

an error when you try to add a new employee without specifying values for the

NOT NULL columns. If you don’t want to give intranet administrators the ability

to add new employee records to the database with this form, and you want to keep

the list of details short, you can simply remove the unwanted columns from the

list.

Before we discuss exactly what’s happening here, and how the functionality works,

let’s implement a few small improvements.

If you agreed to let Visual Web Developer generate the DetailsView columns for

you, it will automatically have rewritten the templates we developed in the last

chapter, and added BoundField controls for each of the columns you’re reading

from the data source.

The HeaderTemplate is still intact, but we want to update it to show a different

display when we’re inserting details for a new employee. Currently, the header is

set to display the Name field of the selected employee, which means it will be empty

when we insert a new employee (as we saw in
Figure 12.15). T
o change this, modify the HeaderTemplate of your DetailsView as follows:

Visual Basic

Dorknozzle\VB\08_AddressBook.aspx
(excerpt)

<%#IIf(Eval("Name") = Nothing, "Adding New Employee", _

Eval("Name"))%>

C#

Dorknozzle\CS\08_AddressBook.aspx
(excerpt)

<%#Eval("Name") == null ? "Adding New Employee" :

Eval("Name")%>

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Now, when we insert a new employee record, DetailsView will display the words

Adding New Employee
in its header; when we’re editing or displaying an existing

employee’s details, it will display the name of that employee, as
Figure 12.16 shows.

Figure 12.16. Adding a new employee, and displaying the new header

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IIf and the Ternary Operator

IIf (in VB) and the ternary operator (in C#) receive as parameters one conditional

expression (which returns True or False), and two values. If the condition is

True, the first value is returned, and if the condition is False, the second value

is returned.

In our case, the conditional expression verifies whether the Name field is empty,

which will be the case if we’re inserting a new row. So, when we’re inserting a

new row, we display
Adding New Employee
in the DetailsView’s header; otherwise, we display the name of the employee whose details are being edited. One minor hitch with this solution is that the GridView isn’t instantly updated

when we make a change using the DetailsView control. Try modifying the name

of a user; even after you click the
Update
link in the DetailsView, the GridView

will show the old value. Only after you reload the page will the data be displayed

correctly by the GridView.

This issue occurs because the GridView is populated before the DetailsView updates

the database. To avoid this problem, we could use a simple workaround that forces

the GridView to update itself in response to the occurrence of certain events raised

by the DetailsView control. These events are ItemUpdated, ItemDeleted, and

ItemInserted. Use Visual Web Developer to generate the event handlers for these

events, and update the code like this:

Visual Basic

Dorknozzle\VB\09_AddressBook.aspx.vb
(excerpt)

Protected Sub employeeDetails_ItemUpdated(

➥ ByVal sender As Object, ByVal e As

➥ System.Web.UI.WebControls.DetailsViewUpdatedEventArgs)

➥ Handles employeeDetails.ItemUpdated

grid.DataBind()

End Sub

Protected Sub employeeDetails_ItemDeleted(

➥ ByVal sender As Object, ByVal e As

➥ System.Web.UI.WebControls.DetailsViewDeletedEventArgs)

➥ Handles employeeDetails.ItemDeleted

grid.DataBind()

End Sub

Protected Sub employeeDetails_ItemInserted(

➥ ByVal sender As Object, ByVal e As

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➥ System.Web.UI.WebControls.DetailsViewInsertedEventArgs)

➥ Handles employeeDetails.ItemInserted

grid.DataBind()

End Sub

C#

Dorknozzle\CS\09_AddressBook.aspx.cs
(excerpt)