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Persisting the Selected Items on Sorting/Paging/Filtering
By default RadListView clears its selected items upon sorting, paging or filtering. To persist the selection across these events, follow the below steps:
-
Handle the ItemCommand event of the listview.
-
When "Select" command occurs, store the key values for the selected item in a Session variable.
-
When "Deselect" command occurs, remove the key values for the deselected item from the Session variable.
-
Handle the PreRender event of the listview.
-
In the PreRender event traverse the listview items and compare their key values to the values saved in the Session variable. Whenever you find a match, mark the item as selected.
-
Rebind the listview at the end of the PreRender event handler.
C#
<telerik:RadFilter RenderMode="Lightweight" ID="RadFilter1" runat="server" FilterContainerID="RadListView1">
</telerik:RadFilter>
<telerik:RadListView ID="RadListView1" runat="server" DataKeyNames="CustomerID" OnNeedDataSource="RadListView1_NeedDataSource"
AllowPaging="True" AllowMultiItemSelection="True" OnItemCommand="RadListView1_ItemCommand"
OnPreRender="RadListView1_PreRender">
<AlternatingItemTemplate>
<tr class="rlvA">
<td>
<asp:Button ID="SelectButton" runat="server" CommandName="Select" CssClass="rlvBSel"
Text=" " />
</td>
<td>
<asp:Label ID="CustomerIDLabel" runat="server" Text='<%# Eval("CustomerID") %>' />
</td>
<td>
<asp:Label ID="CompanyNameLabel" runat="server" Text='<%# Eval("CompanyName") %>' />
</td>
<td>
<asp:Label ID="ContactNameLabel" runat="server" Text='<%# Eval("ContactName") %>' />
</td>
<td>
<asp:Label ID="ContactTitleLabel" runat="server" Text='<%# Eval("ContactTitle") %>' />
</td>
<td>
<asp:Label ID="CountryLabel" runat="server" Text='<%# Eval("Country") %>' />
</td>
</tr>
</AlternatingItemTemplate>
<ItemTemplate>
<tr class="rlvI">
<td>
<asp:Button ID="SelectButton" runat="server" CommandName="Select" CssClass="rlvBSel"
Text=" " />
</td>
<td>
<asp:Label ID="CustomerIDLabel" runat="server" Text='<%# Eval("CustomerID") %>' />
</td>
<td>
<asp:Label ID="CompanyNameLabel" runat="server" Text='<%# Eval("CompanyName") %>' />
</td>
<td>
<asp:Label ID="ContactNameLabel" runat="server" Text='<%# Eval("ContactName") %>' />
</td>
<td>
<asp:Label ID="ContactTitleLabel" runat="server" Text='<%# Eval("ContactTitle") %>' />
</td>
<td>
<asp:Label ID="CountryLabel" runat="server" Text='<%# Eval("Country") %>' />
</td>
</tr>
</ItemTemplate>
<EmptyDataTemplate>
<div class="RadListView RadListView_Default">
<div class="rlvEmpty">
There are no items to be displayed.</div>
</div>
</EmptyDataTemplate>
<LayoutTemplate>
<div class="RadListView RadListView_Default">
<table cellspacing="0" style="width: 100%;">
<thead>
<tr class="rlvHeader">
<th>
</th>
<th>
<asp:LinkButton ID="LinkButton1" runat="server" CommandName="Sort" CommandArgument="CustomerID">CustomerID</asp:LinkButton>
</th>
<th>
<asp:LinkButton ID="LinkButton2" runat="server" CommandName="Sort" CommandArgument="CompanyName">CompanyName</asp:LinkButton>
</th>
<th>
<asp:LinkButton ID="LinkButton3" runat="server" CommandName="Sort" CommandArgument="ContactName">ContactName</asp:LinkButton>
</th>
<th>
<asp:LinkButton ID="LinkButton4" runat="server" CommandName="Sort" CommandArgument="ContactTitle">ContactTitle</asp:LinkButton>
</th>
<th>
<asp:LinkButton ID="LinkButton5" runat="server" CommandName="Sort" CommandArgument="Country">Country</asp:LinkButton>
</th>
</tr>
</thead>
<tfoot>
<tr>
<td colspan="6">
<telerik:RadDataPager RenderMode="Lightweight" ID="RadDataPager1" runat="server">
<Fields>
<telerik:RadDataPagerButtonField FieldType="FirstPrev" />
<telerik:RadDataPagerButtonField FieldType="Numeric" />
<telerik:RadDataPagerButtonField FieldType="NextLast" />
<telerik:RadDataPagerPageSizeField />
</Fields>
</telerik:RadDataPager>
</td>
</tr>
</tfoot>
<tbody>
<tr id="itemPlaceholder" runat="server">
</tr>
</tbody>
</table>
</div>
</LayoutTemplate>
<SelectedItemTemplate>
<tr class="rlvISel">
<td>
<asp:Button ID="DeselectButton" runat="server" CommandName="Deselect" CssClass="rlvBSel"
Text=" " />
</td>
<td>
<asp:Label ID="CustomerIDLabel" runat="server" Text='<%# Eval("CustomerID") %>' />
</td>
<td>
<asp:Label ID="CompanyNameLabel" runat="server" Text='<%# Eval("CompanyName") %>' />
</td>
<td>
<asp:Label ID="ContactNameLabel" runat="server" Text='<%# Eval("ContactName") %>' />
</td>
<td>
<asp:Label ID="ContactTitleLabel" runat="server" Text='<%# Eval("ContactTitle") %>' />
</td>
<td>
<asp:Label ID="CountryLabel" runat="server" Text='<%# Eval("Country") %>' />
</td>
</tr>
</SelectedItemTemplate>
</telerik:RadListView>C#
private ArrayList SelectedItems
{
get
{
if (Session["temp"] == null)
{
Session["temp"] = new ArrayList();
}
return (ArrayList)Session["temp"];
}
set
{
Session["temp"] = value;
}
}
protected void RadListView1_NeedDataSource(object sender, RadListViewNeedDataSourceEventArgs e)
{
OleDbConnection conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + Server.MapPath("~/App_Data/Nwind.mdb"));
OleDbDataAdapter adapter = new OleDbDataAdapter();
adapter.SelectCommand = new OleDbCommand("SELECT * FROM Customers", conn);
DataTable myDataTable = new DataTable();
conn.Open();
try
{
adapter.Fill(myDataTable);
}
finally
{
conn.Close();
}
RadListView1.DataSource = myDataTable;
}
protected void RadListView1_ItemCommand(object sender, RadListViewCommandEventArgs e)
{
ArrayList temp = SelectedItems;
if (e.CommandName == RadListView.SelectCommandName && e.ListViewItem is RadListViewDataItem)
{
RadListViewDataItem dataItem = (RadListViewDataItem)e.ListViewItem;
string customerID = dataItem.GetDataKeyValue("CustomerID").ToString();
temp.Add(customerID);
SelectedItems = temp;
}
if (e.CommandName == RadListView.DeselectCommandName && e.ListViewItem is RadListViewDataItem)
{
RadListViewDataItem dataItem = (RadListViewDataItem)e.ListViewItem;
string customerID = dataItem.GetDataKeyValue("CustomerID").ToString();
temp.Remove(customerID);
SelectedItems = temp;
}
}
protected void RadListView1_PreRender(object sender, EventArgs e)
{
if (SelectedItems.Count > 0)
{
foreach (RadListViewDataItem item in RadListView1.Items)
{
string customerID = item.GetDataKeyValue("CustomerID").ToString();
if (SelectedItems.Contains(customerID))
{
item.Selected = true;
}
}
RadListView1.Rebind();
}
}