How to submit a form to an external controller without leaving the current page??

[eluser]cahva[/eluser]
Yes if js is enabled, use AJAX to submit and update the page. If not, send the form and redirect to the page where the form was submitted. You can either trust $_SERVER['HTTP_REFERER'] or like I did, set flashdata(for example previous_url) that you can use to redirect to the previous page.