How to remember the selected checkboxes between each paging-press - asp.net

Question

I have a listview with paging. Every paging has 10 rows with with a username, an email and a checkbox.
I need to be able to check a couple of checkboxes, in different "pagings", press a button and send an email every to ever user that has been checked.
Trouble is I don't really know how to remember the selected checkboxes between each paging-press.
Are you with me?
Deos anyone have a similar solution or a few tips on how to do this?
I'd prefer to solv this without jQuery, but ordinare javascript or a C# solution works fine.
Thanks in advance!

Answer 1

Try this
http://forums.asp.net/t/1619741.aspx?Remember+checkboxes+in+ListView
you could maintain a List<> of selections (say ID to each record, unique value) and would have to persist that list in the ViewState. update the list on a page change. bind the checkbox checked property through a code-behind function that checks whether the id is in the list.
here's a sample:
<asp:ListView ID="ListView1" runat="server" OnPagePropertiesChanging="ListView1_PagePropertiesChanging">
<LayoutTemplate>
<table id="Table2" runat="server" class="listview" width="100%">
<tr>
<td>
<table id="itemPlaceholderContainer" runat="server">
<tr>
<th>
</th>
<th>
</th>
<th id="thid" runat="server" visible="false">
ID
</th>
<th id="thname" runat="server">
Name
</th>
</tr>
<tr id="itemPlaceholder" runat="server">
</tr>
</table>
</td>
</tr>
<tr id="Tr3" runat="server">
<td id="Td2" runat="server" style="">
<asp:DataPager ID="DataPager1" runat="server" PageSize="5" PagedControlID="ListView1"
OnPreRender="DataPager1_PreRender">
<Fields>
<asp:NumericPagerField />
</Fields>
</asp:DataPager>
</td>
</tr>
</table>
</LayoutTemplate>
<ItemTemplate>
<tr>
<td>
<input type="checkbox" id="CheckBox1" runat="server" value='<%# Eval("ID") %>' checked='<%# Selected(Eval("ID")) %>' />
</td>
<td>
<asp:Label ID="lblID" runat="server" Text='<%# Eval("ID") %>' />
</td>
<td>
<asp:Label ID="lblName" runat="server" Text='<%# Eval("Name") %>' />
</td>
</tr>
</ItemTemplate>
</asp:ListView>
code-behind:
List<string> cBoxSelections = new List<string>();
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
BindListView();
}
}
private void BindListView()
{
ListView1.DataSource = CreateDataSource();
ListView1.DataBind();
}
protected DataTable CreateDataSource()
{
DataTable dt = new DataTable();
DataRow dr;
dt.Columns.Add(new DataColumn("ID", typeof(Int32)));
dt.Columns.Add(new DataColumn("Name", typeof(string)));
for (int i = 0; i < 33; i++)
{
dr = dt.NewRow();
dr[0] = i;
dr[1] = string.Concat("Name",i.ToString());
dt.Rows.Add(dr);
}
return dt;
}
protected Boolean Selected(object sender)
{
Boolean flag = false;
string ID = Convert.ToString(sender);
if (!string.IsNullOrEmpty(ID))
{
flag = cBoxSelections.Exists(item => item.Equals(ID));
}
return flag;
}
private void UpdateSelections()
{
if (ViewState["sel"] != null)
{
cBoxSelections = (List<string>)ViewState["sel"];
}
foreach (ListViewDataItem item in ListView1.Items)
{
HtmlInputCheckBox cbox = (HtmlInputCheckBox)item.FindControl("CheckBox1");
if (cbox != null)
{
string selectedItem = cBoxSelections.Find(key => key.Equals(cbox.Value));
if (selectedItem == null)
{
if (cbox.Checked.Equals(true))
{
cBoxSelections.Add(cbox.Value);
}
}
if (selectedItem != null)
{
if (cbox.Checked.Equals(false))
{
cBoxSelections.Remove(cbox.Value);
}
}
}
}
if (cBoxSelections.Count > 0)
{
ViewState["sel"] = cBoxSelections;
}
}
protected void DataPager1_PreRender(object sender, EventArgs e)
{
BindListView();
}
protected void ListView1_PagePropertiesChanging(object sender, PagePropertiesChangingEventArgs e)
{
UpdateSelections();
}
you need the routines Selected (that returns a boolean) and UpdateSelections (which maintains), the rest of the code simply gets the ListView to demonstrate the sample along with dummy data.