ASP.NET: How do I navigate to a page after clicking a checkbox?

Question

I have some checkboxes and a dropdownlist when the value changes I want to refresh the page while passing the new value. I tried using autopostback; however, the value is already in the url previously so when the postback occurs the value never changes.

Example:

CurrentPage: page.aspx?tab=Home&checkbox=True

Then I uncheck the checkbox so I want it to go to the following page...

IntendedPage: page.aspx?tab=Home&checkbox=False

But instead I the autopostback gives me this page...

DestinationPage: page.aspx?tab=Home&checkbox=True

Because, I handle the building of the url through a function on my page. Perhaps I'm doing something wrong by this point. If so I'd be happy to be corrected on my current setup. What I think I need to know though is how to load a custom URL on the checkbox.checkchanged event. I hope this made sense, if not let me know I'll try and clarify it. Thanks!

Answer 1

This is very easy to do through javascript. First add onclick="checkCheckBox(this);" to your checkbox.

<script language = "javascript" type="text/javascript"> 
function checkCheckBox(checkbox) {
        if (checkbox.checked) {
            window.location.href = '../page.aspx?tab=Home&checkbox=True';
        }
        else {
            window.location.href = '../page.aspx?tab=Home&checkbox=False';
        }
    }
</script>

This should do it pretty easily.

Answer 2

You could try something like this ( I have not tested, it was just an idea).

 protected void CheckBox1_CheckedChanged ( object sender, EventArgs e )
    {
        string url = "page.aspx?tab=Home&checkbox="+ CheckBox1.Checked.ToString();
        Response.Redirect ( url );
    }

And then on the page:

<asp:CheckBox ID="CheckBox1" runat="server" 
oncheckedchanged="CheckBox1_CheckedChanged" />

VB.NET Conversion

Protected Sub CheckBox1_CheckedChanged(sender As Object, e As System.EventArgs) Handles CheckBox1.CheckedChanged
       Dim url = "page.aspx?tab=Home&checkbox=" & CheckBox1.Checked.ToString()
       Response.Redirect(url)
End Sub

Answer 3

This behavior is caused by the viewstate. The checkbox use it to persists its property, especially the checked property.

Actually, there is no out of the box link between a control and query string.

In your case, you will have two options, depending on your needs :

• in the Checked event, build the expected url, and redirect the user to this page. The drawback is that you "loose" the viewstate and thus, the controls' state.
• instead of using postbacks, use client side script (jQuery is your friend) to hide/show parts of the page. If the url matters, use # in the urls because it does allow staying on the same page.