How to avoid Page Reload Resend-Data message with PHP

Question

I am relatively new to PHP, so my apologies if the answer is trivial. Lol

I wrote a simple Contact Us email form (actually a WordPress page-template file). All the code is in one file.

After the user submits the form and the email is sent, the file generates a Thank You message.

If the user reloads the Thank You page, they are prompted to "Resend the Form Data," which is why I am asking this question.

My question: How do I avoid the prompt to resend the form data and still keep all of my code (including the Thank You data) in one file?

EDIT: I've seen folks use headers( Location: ), but I don't think that will work for if I want to keep all my code in one file.

Answer 1

You could redirect to a different query.

header("Location: ?page=thankyou");

Then, you don't even need to check if the POST data was sent. Just display the thank you page if page is equal to thank you.