{"id":2418,"date":"2021-08-04T06:56:44","date_gmt":"2021-08-04T06:56:44","guid":{"rendered":"https:\/\/phptutorial.net\/?page_id=2418"},"modified":"2021-08-04T09:05:31","modified_gmt":"2021-08-04T09:05:31","slug":"php-prg","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-tutorial\/php-prg\/","title":{"rendered":"PHP PRG (Post-Redirect-Get)"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn how to use the PHP PRG (Post-Redirect-Get) technique to prevent the double form submission problem.<\/p>\n\n\n\n

The double submit problem #<\/a><\/h2>\n\n\n\n

To change data on the server via a form<\/a>, you often use the post method. When a form is submitted, you validate the data<\/a>, update the database, and display the output.<\/p>\n\n\n\n

However, if you click the Refresh (or Reload) button of the browser after the form is submitted, the browser will submit the form again. <\/p>\n\n\n\n

Since the form uses the POST method, the browser will prompt for confirmation like this:<\/p>\n\n\n\n

\"PHP<\/figure>\n\n\n\n

If you click the Continue button, the browser will actually submit the form a second time. It’s a notorious double submit problem that may cause many issues. <\/p>\n\n\n\n

For example, you may have duplicate records in the database. If the form processes the payment, it’ll charge the customer twice.<\/p>\n\n\n\n

The following diagram illustrates the double submit problem:<\/p>\n\n\n\n

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Introduction to the PHP PRG (post-redirect-get) technique #<\/a><\/h2>\n\n\n\n

The PRG (post-redirect-get) technique helps you solve the double submit problem. The post-redirect-get works as follows:<\/p>\n\n\n\n