ListView.DataKeys Property

 
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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)

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

Property Value

Type: System.Web.UI.WebControls.DataKeyArray

An object that contains the data key for each item in a ListView control.

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.

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.

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 { }
  }
}

.NET Framework
Available since 3.5
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