Problem : Resubmitting form when click "f5" to reload the page. There are 3 different solutions :
Solution 1 :
1) page1.php does 3 different tasks :
Task 1 is show a textbox and submit button in a form if $_Get['success']=="true".
Task 2 is show errors message such as "name is used by other" or "multiple inputs too fast" if $_Get['success']=="false".
Task 3 is show the records from database if $_Get['success']=="".

2) page2.php does the data processing. Process the data after the user click submit button on page1.php. Then :
Task 1 is redirect the user to page1.php?success=true by code header('Location: page1.php?success=true'); if data process successful.
Task 2 is redirect the user to page1.php?success=false by the code of header('Location: page1.php?success=false'); if data process fail.

How it works?
1) User submit data by clicking the "submit button on page1.php,
2) Post method <form name="frm_register" action="page2.php" method="post"> jump to page2.php to process the data.
3) After page2.php finish process the data, it redirect user to page1.php?successful=true by header('Location: page1.php?successful=true'); (If you use header to redirect, the page will not remember anything happened previously, it will not remember page1.php did submit the form before). That's why it will not resubmit form when click "f5" to refresh the page1.php.

4) User submit data fail (because the name is used by other or because multiple input too fast), redirect to page1.php?success=false, and error message pop up.

5) If the user reload the page, it will still pop up the error message. It will not resubmit the form, because of this two reasons :
Reason 1 : The page doesn't show the form when $_Get['success']=="false".
Reason 2 : Just now you redirect to page1.php by header(), so page1.php will not remember the form is sent before.

6) If the user click "back" button, the page url will change the url back to page1.php?success=true which shows records and doesn't show the form. If click "back" button again, it will change the url back to page1.php which shows the form, but it will not resubmit the form because just now page2.php had redirected to page1.php by using header() which make page1.php forget everything in the past.

Note that header('Location: http://localhost/plekz/page1.php'); must has spacing after the sign of : and must have full path of url which has http://.

Weakness of solution 1 : If display records must depend of php if else statement, then you need to wrap the html codes of displaying records by php echo. It will be a lot of works to wrap all html in php echo.


Solution 2 :
1) page1.php does 2 different tasks :
Task 1 is show a textbox and submit button in a form if $_SESSION['error123']=="".
Task 2 is show error message if $_SESSION['error123']="samename".
Task 3 is process the data after the user click submit button :
- If process data successful, redirect user to page2.php to view records by code header('Location: page2.php');
- If process data fail because of same name or multiple input too fast, redirect use to page1.php?error123=samename by code header('Location: page1.php?error123=samename');

2) page2.php displays the records from database.

How it works?
1) User submit data by clicking the "submit button on page1.php,
2) Post method <form name="frm_register" action="page1.php" method="post"> jump to page1.php (same page) to process the data.
3) After finish process the data, it will use header() to redirect user to page2.php if no error, it will redirect user to page1.php if there is error.
If the user press "f5" button to reload the page or click "back" button, it will not resubmit the form because just now page1.php use header() to redirect this page, so this page won't remember everything in the past. So It don't remember the form is submitted before, so it will not resubmit the form when the user press "f5" button and "back" button.

Example of codes :

If you want to redirect user to page2.php after user click "OK" button on javascript alert box, u can use this codes : echo "<script type='text/javascript'>alert('Your info FAIL to be saved for this time, because each visitor can save info for 1 time per minute.'); document.write('Loading....'); window.location='page2.php'; </script>";

Note that header('Location: http://localhost/plekz/page1.php'); must has spacing after the sign of : and must have full path of ur which has http://


Solution 3 : You can use onclick to call ajax function to submit the form. So it will not recall the funtion to resubmit the form until u click submit button again. Example of codes :
Reference at http://stackoverflow.com/questions/7747569/prevent-resubmit-form-after-click-back-button/7747700


Posted by Zac1987 on 13 October, 2011

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