ListView.DataKeys Property (System.Web.UI.WebControls)

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ListView.DataKeys Property

Gets a collection of DataKey objects that represent the data-key value for each item in a ListView control.

Namespace: System.Web.UI.WebControls
Assembly: System.Web.Extensions (in System.Web.Extensions.dll)

Syntax

Visual Basic

<BrowsableAttribute(False)> _
Public Overridable ReadOnly Property DataKeys As DataKeyArray

[BrowsableAttribute(false)]
public virtual DataKeyArray DataKeys { get; }

Visual C++

[BrowsableAttribute(false)]
public:
virtual property DataKeyArray^ DataKeys {
	DataKeyArray^ get ();
}

[<BrowsableAttribute(false)>]
abstract DataKeys : DataKeyArray
[<BrowsableAttribute(false)>]
override DataKeys : DataKeyArray

Property Value

Type: System.Web.UI.WebControls.DataKeyArray
An object that contains the data key for each item in a ListView control.

Remarks

When the DataKeyNames property is set, the ListView control automatically creates a DataKey object for each item in the control. The DataKey object contains the values of the field or fields that are specified in the DataKeyNames property. The DataKey objects are then added to the control's DataKeys collection.

Use the DataKeys property to retrieve the DataKey object for a specific data item in the ListView control.

You can use the SelectedDataKey property to retrieve the DataKey object for the currently selected item. You can also use the SelectedValue property to retrieve the data-key value for the currently selected item directly.

You can use the ListViewDataItem.DisplayIndex property to retrieve the DataKey object for the item for which a command button was clicked.

Examples

The following example shows how to use the DataKeys property to determine the data-key values for the items in a ListView control. It also shows how to preserve the user selection based on a data item instead of the default behavior that uses the index.

Visual Basic


Sub ContactsListView_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
  If ContactsListView.SelectedIndex >= 0 Then
    ViewState("SelectedKey") = ContactsListView.SelectedValue
  Else
    ViewState("SelectedKey") = Nothing
  End If
End Sub

Sub ContactsListView_DataBound(ByVal sender As Object, ByVal e As EventArgs)
  For i As Integer = 0 To ContactsListView.Items.Count - 1
    ' Ignore values that cannot be cast as integer.
    Try
      If Convert.ToInt32(ContactsListView.DataKeys(i).Value) = Convert.ToInt32(ViewState("SelectedKey")) Then _
        ContactsListView.SelectedIndex = i
    Catch
    End Try
  Next
End Sub


void ContactsListView_SelectedIndexChanged(Object sender, EventArgs e)
{
  if (ContactsListView.SelectedIndex >= 0)
    ViewState["SelectedKey"] = ContactsListView.SelectedValue;
  else
    ViewState["SelectedKey"] = null;
}

void ContactsListView_DataBound(Object sender, EventArgs e)
{
  for (int i = 0; i < ContactsListView.Items.Count; i++)
  {
    // Ignore values that cannot be cast as integer.
    try
    {
        if ((int)ContactsListView.DataKeys[i].Value == (int)ViewState["SelectedKey"])
            ContactsListView.SelectedIndex = i;
    }
    catch { }
  }
}

Version Information

.NET Framework

Supported in: 4, 3.5

Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference

ListView Class

System.Web.UI.WebControls Namespace

DataKey

DataKeyArray

DataKeyNames

SelectedDataKey

Other Resources

ListView Web Server Control Overview