action is not called after a php request

Question

I want to send a download link to user by mailchimp, after they filled out a email form.

The PHP Request listener is calling my_function(), but inside this function the action is not called.

The functions and the action are working. Also after put the do_action(); inside the createDownloadButton() it will be called. Only after write the action inside my_function() it doesn't work?!

Inside the functions.php:

        /**
        * Place a button
        * @return string html-form
        * usage: [download_button download_name='my_download']
        */    
        function createDownloadButton($atts ){
          //shortcode input
          $a = shortcode_atts( array(
              'download_name' => ''
          ), $atts );


            $result = '<form class="form" method="post" action="' . esc_url( $_SERVER['REQUEST_URI'] ) . '">';
              $result .= '<input hidden name="title" value="'.$a['download_name'].'"  type="text" >'; 

              $result .= '<p>';
               $result .= '<input autofocus class="imput_mail" name="email" placeholder="email adress*" value="" type="email" required>'; 
               $result .= '<input class="bt" id="btn" onClick="ga(\'send\', \'event\', \'push_button\', \'some_analytics_event\');" value="" type="submit">';
              $result .= '</p>';


          $result .= '</form>';
          return $result;
        }
        add shortcode('download_button', 'createDownloadButton' );



    /**
    *  PHP request listener
    */
    if( isset($_POST['email']) && isset($_POST['title']) ){
       my_function($_POST['email'],$_POST['title']);
    }


    /**
    *  Do some action here
    */
    function my_function($mail, $title){
     //echo works!
     echo "<script>console.log( 'email: ".$mail." | download: ".$title."' );</script>"; 
     //why the action doen't work here?
     do_action('memberToMailchimpList', '<API-KEY>', $mail, '<LIST-ID>', '<INTEREST>'); 
    }

Answer 1

I just solved it!

The problem was, that the php request handling works different in wordpress. There has to be a workaround with a admin_post.php hook:

Instead of if( isset($_POST['email']) && isset($_POST['title']) ){...}

I had to use this hook:

add_action( 'admin_post_nopriv_process_form', 'process_form_data' );
add_action( 'admin_post_process_form', 'process_form_data' );
function process_form_data() {
  my_function($_POST['email'],$_POST['title']);
  wp_redirect($_POST['url']);
}

A hidden form field is used to hook in this function. For the redirect, I created another hidden field in the form, to redirect to user back to the previous site:

  $current_url="//".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'];
  //...
  $result .= '<input type="hidden" name="url" value="'.$current_url.'">'; //redirect
  $result .= '<input type="hidden" name="action" value="process_form">'; //hook

Source: adaptiveweb.com