I have build a custom WordPress admin page. In it i’m extending the wp-list-table class like demonstrate here https://premium.wpmudev.org/blog/wordpress-admin-tables/.

I have a form that sets some arguments to filter the results that will be showed in the list.

It works great.

But I want to add a button to download the filtered data.

like to see here :

The button is outputed in the extra_tablenav function.

public function extra_tablenav($which) {
        if ( $which == "top" ){

            $data = $this->generate_WP_Query();

            if( isset( $data ) ) {
                submit_button( 'Download the csv', 'primary', 'download_stock_csv' );

                global $plugin_page;

                if ( $plugin_page == 'dw-custom-stock-export' && isset( $_POST['download_stock_csv'] ) ) {
                    $this->generate_stock_report_csv();
                }
            }

         }
         if ( $which == "bottom" ){
            //The code that goes after the table is there
         }
    }

But I always get a empty query.

Anybody got an idea how to do this?