Contact Form 7: use hook created using wpcf7_before_send_mail for only one contact form by id

Question

I am working on a site with several forms created using Contact Form 7. For one of these forms, I am passing variables that I collected using a hidden input field in the fo

Answer 1

Contact Form 7 uses hidden input type to store form id. It uses hidden field name _wpcf7. You can get the form Id like this way.

$form_id = $contact_form->posted_data['_wpcf7'];

So you final code should be

add_action( 'wpcf7_before_send_mail', 'wpcf7_add_text_to_mail_body' );

function wpcf7_add_text_to_mail_body($contact_form){
 $form_id = $contact_form->posted_data['_wpcf7'];
 if ($form_id == 123): // 123 => Your Form ID.
     $values_list = $_POST['valsitems'];
     $values_str = implode(", ", $values_list);

     // get mail property
     $mail = $contact_form->prop( 'mail' ); // returns array 

     // add content to email body
     $mail['body'] .= 'INDUSTRIES SELECTED';
     $mail['body'] .= $values_list;


     // set mail property with changed value(s)
     $contact_form->set_properties( array( 'mail' => $mail ) );
 endif;

}

Hope this helps.