get the value of all the checked checkboxes on button click - asp.net

Question

I have created a table in my .aspx file that looks like this:
Here is the code that does this:
<!-- code for generating the "add selected sessions" button -->
<table>
<tr>
<td><strong>Individual Sessions</strong></td>
<td >
<div class="addButton" style="text-align: center;">
<asp:LinkButton ID="LinkButton2" runat="server" Text="Add Selected Sessions" OnClick="btnAddToCart_Click" />
</div>
</td>
</tr>
</table>
<!-- add all the sessions for the user to select -->
<asp:Repeater ID="rptFeesSession" runat="server">
<HeaderTemplate>
<table >
</HeaderTemplate>
<ItemTemplate>
<asp:HiddenField ID="hdnIsSession" runat="server" Value='<%#Eval("isSession")%>' />
<tr runat="server" visible='<%# Eval("isSession")%>'>
<td valign="top" colspan="2" style="position: relative;">
<asp:HyperLink CssClass="siteColorFG popBtn" ID="hlFeeType" runat="server" Text='<%#Eval("title")%>' NavigateUrl="javascript:;"/>
</td>
<td valign="top">
<div class="">
<asp:CheckBox ID="LinkButton3" CommandArgument='<%#Eval("id")%>'CssClass="checkB" OnClick="btnAddToCart_Click" runat="server" Text='<%#Eval("amount", "{0:C}")%>' />
</div>
</td>
</tr>
</ItemTemplate>
<FooterTemplate>
</table>
</FooterTemplate>
</asp:Repeater>
In my code behind file i want to capture all the checkboxes that have been checked and their respective CommandArgument values.
protected void btnAddToCart_Click(object sender, EventArgs e)
{
using (MyEntities db = new MyEntities())
{
//button was clicked. fetch all the check boxes from the rptFeesSession repeater into an int[]
}
}

Answer 1

There are several issues in your code (including conceptual / logic)
Item events in a Repeater should address item related things.
Click event handler has no access to CommandArgument attribute. Use Command instead.
Checkbox control doesn't support onclick event.
Checkbox events can run immediately only when there is AutoPostback="true".
If you want to refresh all repeater data on change of any checkbox then you can do something like this.
<asp:ScriptManager runat="server" ID="scriptMgr" /><%-- Strongly recommended --%>
<asp:UpdatePanel runat="server">
<ContentTemplate>
<asp:Repeater ID="rptFeesSession" runat="server">
<HeaderTemplate>
<table>
</HeaderTemplate>
<ItemTemplate>
<asp:HiddenField ID="hdnIsSession" runat="server" Value='<%#Eval("isSession")%>' />
<tr runat="server" visible='<%# Eval("isSession")%>'>
<td colspan="2" style="position: relative;">
<asp:HyperLink CssClass="siteColorFG popBtn" ID="hlFeeType" runat="server" Text='<%#Eval("title")%>' NavigateUrl="javascript:;" />
</td>
<td>
<div class="">
<asp:HiddenField runat="server" ID="hidID" Value='<%#Eval("id") %>' />
<asp:CheckBox ID="LinkButton3"
AutoPostBack="true" CssClass="checkB"
OnCheckedChanged="LinkButton3_CheckedChanged" runat="server"
Text='<%#Eval("amount", "{0:C}")%>' />
</div>
</td>
</tr>
</ItemTemplate>
<FooterTemplate>
</table>
</FooterTemplate>
</asp:Repeater>
</ContentTemplate>
</asp:UpdatePanel>
//.cs
protected void LinkButton3_CheckedChanged(object sender, EventArgs e)
{
decimal total = 0;
using (MyEntities db = new MyEntities())
{
foreach (RepeaterItem item in rptFeesSession.Items)
{
var chk = item.FindControl("LinkButton3") as CheckBox;
if(chk!=null && chk.Checked){
string id = (item.FindControl("hidID") as HiddenField).Value;
total += decimal.Parse(chk.Text);
//do stuff
}
}
}
}