Why Use Post/Redirect/Get (PRG) to Prevent Data Resubmission?

Understanding the Intrinsically Confusing "Post/Redirect/Get" Pattern

Despite encountering numerous overviews of the "post/redirect/get" pattern, grasping its intricacies can remain elusive. Let's delve deeper to elucidate this concept.

Post: Sending Sensitive Data

In certain instances, applications require users to submit sensitive information, such as passwords or credit card numbers. Using the HTTP POST method, these values are securely embedded in the body of the request and not exposed in the URL.

Redirect: Avoiding Multiple Posts

However, after POST processing, immediately returning a response page can lead to accidental re-submission if users refresh the page. To prevent this, a redirect is issued to a new URL. This new URL no longer contains the POST payload, safeguarding it from repeated submission.

Get: Retrieving Results

Finally, the user lands on the GET URL, which typically displays the results of the POST operation. This segregation of data entry (POST) from data display (GET) ensures data integrity and a cleaner user experience.

Illustrative Visualization

Consider the following diagram:

[Image: "The Problem" - POST data enters a funnel, but leaving it triggers re-POST. "The Solution" - POST data enters a funnel, which redirects to a GET page]

By understanding the problem of re-submission and the role of redirection in mitigating it, the "post/redirect/get" pattern becomes more intuitive.

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