You can do this on the client or the server side
Client side using javascript/jquery
As the checkboxes are added dynamically you will need to use the on method to bind the checkboxes to the function and fire it when their state changes.
$(document).ready(function() {
$(".checkbox").on("change", function() {
if(!$(this).is(":checked")){
$(".selectAll").prop('checked', false);
}
});
});
Here is a jsFiddle with a full functioning select All that will:
- Select All / Deselect All
- Untick Select All when one of the checkboxes is unticked
- Tick select All when all checkboxes are ticked
Server side
use an event handler to on a postback(ajax) when a checkbox is unticked and loop through all checkboxes and untick them
Font-end uses ajax to do a partial postback to update the gridview.
the select all checkbox and gridview checkboxes will trigger the postback.
<asp:UpdatePanel runat="server">
<ContentTemplate>
<asp:GridView ID="gvCheckBoxes" runat="server">
<Columns>
<asp:TemplateField >
<ItemTemplate>
<asp:CheckBox ID="cbCheckBox" OnCheckedChanged="CheckBoxChanged" AutoPostBack="true" runat="server" />
</ItemTemplate>
/asp:TemplateField>
</Columns>
</asp:GridView>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="cbSelectAll"/>
</Triggers>
</asp:UpdatePanel>
Code Behind
The select All check box event handler loops through the gridview and finds the checkboxes.
It ticks them if the select all checkbox is ticked otherwise it unticks them
The gridview checkbox event handler loops through the checkboxes and sets a flag to determine if it should tick or untick the select all checkbox. It exists the loop if any of the checkboxes are not ticked as select all must therefore be unticked as well
public void SelectAll (Object sender, Eventargs e)
{
foreach (var row in grid.Rows)
{
var checkBox = (CheckBox)row.FindControl("cbCheckBox");
checkBox.Checked = cbSelectAll.Checked;
}
}
public void CheckBoxChanged(Object sender, Eventargs e)
{
var isSelectAll = true;
foreach (var row in grid.Rows)
{
var checkBox = (CheckBox)row.FindControl("cbCheckBox");
if(!checkBox.Checked)
{
isSelectAll = false;
break;
}
}
cbSelectAll.Checked = isSelectAll;
}