Creating a form in WordPress in a class-based plugin - php

Question

I have a custom plugin that uses a class. In the class I add an admin dashboard menu item that displays a "Settings" form. Let's say the class looks like this:
class MyPlugin {
function __construct () { ... }
function show_menu_form () {
$url = admin_url("admin_post
echo <<<EOFORM
<form method="POST" action="$url"/>
Click submit to do stuff.
<input type="hidden" name="action" value="do_stuff"/>
<input type="submit/>
</form>
EOFORM;
add_action('wp_post_do_stuff', [$this, '_handle_stuff']);
}
function _handle_stuff () {
echo "Doing stuff...";
}
}
The form prints properly in the dashboard page. When I click submit, it goes to a completely blank screen. What I want it to do is:
Do something
Go back to the same page, showing a message like, "Stuff was done." above the same form, and the user can click the form submit again to do more stuff.
If I leave the action blank on the <form> tag it will go back to the same page, and I can manually process the get/post params myself... that seems like a bad solution (but the only one I can see so far).
Any tips?

Answer 1

You have 2 ways to do this:
Form submit to the same page and before rendering the form you check if the form already submitted. If yes then call a function to display "Stuff was done" and any further steps. If not, then display the form.
In this way, you won't need any javascript in your plugin and I IMOO will be simpler and straight forward.
Submit using AJAX and display the confirm message using javascript. You can read the docs AJAX in Plugins to see how to do this in the admin menu. This is might be a more elegant solution without requiring any page refresh.
Which one to use depends on the requirements of your plugin. Either way, don't forget to validate inputs