Build Your Own ASP.NET 2.0 Web Site Using C# & VB, Second Edition

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

// Add content to the Literal control

li.Text = "Employee ID: <strong>" + e.CommandArgument +

"</strong><br />";

Disabling View State

If you take a look at the definition of the extraDetailsLiteral control

in EmployeeDirectory.aspx, you’ll see that we set its EnableViewState

property to False:

File: EmployeeDirectory.aspx (excerpt)

<asp:Literal ID="extraDetailsLiteral" runat="server"

EnableViewState="false" />

When this property is False, its contents aren’t persisted during postback

events. In our case, once the visitor clicks another View more details button,

all the instances of that Literal control lose their values. This way, at any

given moment, no more than one employee’s ID will be displayed. If you

change EnableViewState to True (the default value), then click the View

more details button, you’ll see that all employee IDs remain in the form,

as they’re persisted by the view state mechanism.

Editing DataList Items and Using

Templates

Continuing our journey into the world of DataList, let’s learn a little more about

its templates, and see how you can use the EditItemTemplate to edit its contents.

Our goal here is to allow users to change the name or username of any employee.

Start by adding another button to the ItemTemplate of the DataList. This button

will read Edit employee Employee Name and, when clicked, it will cause the item

of which it’s a part to become editable.

File: EmployeeDirectory.aspx (excerpt)

<ItemTemplate>

<asp:Literal ID="extraDetailsLiteral" runat="server"

EnableViewState="false" />

Name: <strong><%#Eval("Name")%></strong><br />

Username: <strong><%#Eval("Username")%></strong><br />

<asp:LinkButton ID="detailsButton" runat="server"

Text=<%#"View more details about " & Eval("Name")%>

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Editing DataList Items and Using Templates

CommandName="MoreDetailsPlease"

CommandArgument=<%#Eval("EmployeeID")%> /><br />

<asp:LinkButton ID="editButton" runat="server"

Text=<%#"Edit employee " + Eval("Name")%>

CommandName="EditItem"

CommandArgument=<%#Eval("EmployeeID")%> />

</ItemTemplate>

When an Edit employee button is clicked, we will make the item enter edit mode.

When one of the DataList items is in edit mode, the EditItemTemplate template

of the DataList is used to generate the contents of that item. All the other items

are generated by the ItemTemplate, as usual.

Modify EmployeeDirectory.aspx by adding the EditItemTemplate to the

DataList. The EditItemTemplate contains TextBox controls into which the user

can enter the employee’s name and username, and two buttons: Update Item and

Cancel Editing, whose names are self-explanatory.

File: EmployeeDirectory.aspx (excerpt)

<EditItemTemplate>

Name: <asp:TextBox ID="nameTextBox" runat="server"

Text=<%#Eval("Name")%> /><br />

Username: <asp:TextBox ID="usernameTextBox" runat="server"

Text=<%#Eval("Username")%> /><br />

<asp:LinkButton ID="updateButton" runat="server"

Text="Update Item" CommandName="UpdateItem"

CommandArgument=<%#Eval("EmployeeID")%> />

or

<asp:LinkButton ID="cancelButton" runat="server"

Text="Cancel Editing" CommandName="CancelEditing"

CommandArgument=<%#Eval("EmployeeID")%> />

</EditItemTemplate>

Finally, before you can see your new template, we need to handle the Edit employ-

ee button. Again, when that button is clicked, the DataList’s ItemCommand event

is fired. This time, the CommandName of the new button is EditItem, and when

we discover that this button was clicked, we’ll put the item into edit mode. To

put a DataList item into edit mode, we set its EditItemIndex to the index of

the item, then bind the DataList to its data source again to refresh its contents.

Add this code:

Visual Basic File: EmployeeDirectory.aspx.vb (excerpt)

Protected Sub employeesList_ItemCommand(ByVal source As Object, _

ByVal e As System.Web.UI.WebControls.DataListCommandEventArgs) _

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Chapter 10: Displaying Content Using Data Lists

Handles employeesList.ItemCommand

' Which button was clicked?

If e.CommandName = "MoreDetailsPlease" Then

' Find the Literal control in the DataList item

Dim li As Literal

li = e.Item.FindControl("extraDetailsLiteral")

' Add content to the Literal control

li.Text = "Employee ID: <strong>" & e.CommandArgument & _

"</strong><br />"

ElseIf e.CommandName = "EditItem" Then

' Set the index of the item being edited

employeesList.EditItemIndex = e.Item.ItemIndex

' Bind again the list to update the list

BindList()

End If

End Sub

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

protected void employeesList_ItemCommand(object source,

DataListCommandEventArgs e)

{

// Which button was clicked?

if (e.CommandName == "MoreDetailsPlease")

{

// Find the Literal control in the DataList item

Literal li;

li = (Literal)e.Item.FindControl("extraDetailsLiteral");

// Add content to the Literal control

li.Text = "Employee ID: <strong>" + e.CommandArgument +

"</strong><br />";

}

else if (e.CommandName == "EditItem")

{

// Set the index of the item being edited

employeesList.EditItemIndex = e.Item.ItemIndex;

// Bind again the list to update the list

BindList();

}

}

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Editing DataList Items and Using Templates