MVC Action getting called twice? - asp.net-mvc-3

Question

I am using Asp.Net MVC3, for a project.
In one of the page, I am using MS Charts. In View I have a Image which shows the chart as follows:
<img src="#Url.Action("RenderCharts", "Home", new
{
XAxisColor = ViewBag.XAxisColor,
YAxisColor = ViewBag.YAxisColor,
})" alt="Charts" runat="server" />
I have 2 CheckBoxes, which is used to change Chart Axes Colors. When the checkbox is clicked, page is submitted and checkbox status is stored and based on that Chart is rendered:
bool XAxisColor = (#ViewBag.XAxisColor) ?? true;
bool YAxisColor = #ViewBag.YAxisColor ?? false;
#Html.CheckBox("chkXAxisColor", XAxisColor, new { #Id = "chkXAxisColor",
onClick = "this.form.submit();" })
X Axis Color
#Html.CheckBox("chkYAxisColor", YAxisColor, new { #Id = "chkScatter",
onClick = "this.form.submit();" })
Y Axis Color
When first time the page is loaded, RenderCharts() Action gets called and Chart is rendered.
But when i Click any of the CheckBox, RenderCharts() Action gets called twice.
I could not understand this issue. I have created a sample Application which can be downloaded from here https://www.dropbox.com/s/ig8gi3xh4cx245j/MVC_Test.zip
Any help would be appreciated. Thanks in advance.

Answer 1

This appears to be something to do with Internet Explorer. Using your sample application, everything works fine in both Google Chrome and Firefox, but when using IE9, there are two Action requests on a postback.
Using the F12 developer tools on the network tab, it shows an initial request to RenderCharts which appeared to be aborted:
The (aborted) line in the middle is, I suspect, the additional request you're seeing. Why this happens, I don't know!

Answer 2

Finally got the answer. The problem was
runat="server"
in the Img tag.
Removing runat fixed the issue.

Answer 3

I can eliminate the IE issue in the following manner by simply using a bit of JQuery instead. A few possible advantages...
It eliminates the cross-browser issue.
It is an unobtrusive approach (not mixing javascript and HTML in the view).
You can update the image via ajax.
Create a new file in the scripts folder (e.g. "chart.js") which will simply attach an anonymous function to the the click events of your checkboxes from the document ready function. You would obviously need to include the script reference in your page as well:
$(document).ready(function () {
// Attach a function to the click event of both checkboxes
$("#chkXAxisColor,#chkScatter").click(function () {
// Make an ajax request and send the current checkbox values.
$.ajax({
url: "/Home/RenderCharts",
type: "GET",
cache: false,
data: {
XAxisColor: $("#chkXAxisColor").attr("checked"),
YAxisColor: $("#chkScatter").attr("checked")
},
success: function (result) {
alert(result);
$("#chart").attr("src", result);
}
});
});
});
Best of all, you get to eliminate the javascript from your view :)
...
<div style="margin: 2px 0 2px 0">
#Html.CheckBox("chkXAxisColor", XAxisColor, new { #Id = "chkXAxisColor" })
X Axis Color
#Html.CheckBox("chkYAxisColor", YAxisColor, new { #Id = "chkScatter" })
Y Axis Color
</div>
...
This is of course a very basic example which does eliminate the IE issue but you could get fancier from there in terms of how you update the image + show a loading gif, etc with only a few more lines.
Hopefully it is a workable solution for you!