Form Resubmissions

When you use <Form method="post"> in Remix, as opposed to using the native HTML <form method="post">, Remix does not adhere to the default browser behavior for resubmitting forms during navigation events like clicking back, forward, or refreshing.

The Browser's Default Behavior

In a standard browser environment, form submissions are navigation events. This means that when a user clicks the back button, the browser will typically resubmit the form. For example:

User visits /buy
Submits a form to /checkout
Navigates to /order/123

The browser history stack would look like this:

GET /buy > POST /checkout > *GET /order/123

If the user clicks the back button, the history becomes:

GET /buy - *POST /checkout < GET /order/123

In this situation, the browser resubmits the form data, which could lead to issues such as charging a credit card twice.

Redirecting from Actions

A common practice to avoid this issue is to issue a redirect after the POST request. This removes the POST action from the browser's history. The history stack would then look like this:

GET /buy > POST /checkout, Redirect > GET /order/123

With this approach, clicking the back button would not resubmit the form:

GET /buy - *GET /order/123

Specific Scenarios to Consider

While accidental resubmissions generally don't happen in Remix, there are specific scenarios where they might.

You used <form> instead of <Form>
You used <Form reloadDocument>
You are not rendering <Scripts/>
JavaScript is disabled by the user
JavaScript had not loaded when the form was submitted

It's advisable to implement a redirect from the action to avoid unintended resubmissions.

Additional Resources

Guides

Form Validation

API