How to Redirect Mobile Users for Password Reset in Flask Security

Описание: Learn how to configure Flask Security to send a password reset link as a mobile deeplink, allowing users to reset their passwords directly within a mobile app.
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This video is based on the question https://stackoverflow.com/q/66255958/ asked by the user 'chr0nikler' ( https://stackoverflow.com/u/2766706/ ) and on the answer https://stackoverflow.com/a/66263733/ provided by the user 'jwag' ( https://stackoverflow.com/u/4860303/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Redirect Mobile Users for Password Reset in Flask Security

When developing a mobile application, creating a seamless experience for users is paramount. One of the challenges you might encounter is handling password resets effectively within your app. For instance, you may want users to tap on a deeplink in an email, redirecting them to the password reset form within the app instead of a web view. This is where you might encounter some limitations with frameworks like Flask Security. In this post, we will address how to set up a password reset URL as a mobile deeplink using Flask Security, particularly when it comes to redirecting appropriately and validating tokens.

Understanding the Problem

Let’s break down the problem specific to Flask Security:

Flask Security Behavior: By default, Flask Security requires that the server be contacted to validate the password reset token. If the token is valid, it then redirects users based on the REDIRECT_HOST setting.

Mobile App vs. SPA: Since you are developing a mobile application instead of a Single Page Application (SPA), you don’t want users to interact with a web view for password resets. Instead, you want them to directly enter the password reset form in the app after clicking a link.

Email Link Needs: The email sent to users should contain a deep link that the mobile app can interpret correctly, allowing users to reset their passwords seamlessly.

The Solution

While Flask Security has built-in methods to handle these scenarios, they might not perfectly align with your needs. Here’s a step-by-step approach to achieving the desired functionality:

Step 1: Use the POST /reset/ Endpoint

Direct Verification: You can directly use the POST method on the /reset/ endpoint instead of the GET method. The POST will also verify the token validity.

No Need for Initial GET Call: This means you don’t have to make a GET request first; the POST can handle both token validation and the form submission.

Step 2: Customizing the Email Sending Process

Unfortunately, Flask Security does not provide an out-of-the-box way to configure the password reset links as required. However, you can make it work by customizing the email sending logic:

Override the MailUtil Class: Starting from version 4.0.0 of Flask Security, you can replace the MailUtil class. This allows you to implement your version of the send_mail function that looks for the template named reset_instructions.

Manipulate the Email Body: Since the email has already been rendered, you might need to parse the body and rewrite the URL while preserving the token.

Step 3: Generating the Deep Link

In your customized send_mail function, follow these guidelines to generate a deeplink:

Identify the Token: Ensure that the token is included in the URL.

Create the Deep Link Format: Formulate the URL to fit the deep link format required by your mobile app.

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Consider User Experience

As you implement this solution, consider the following to enhance user experience:

Test the Deep Link: Ensure it opens the mobile application as intended.

Fallback Option: Offer a fallback URL in case users open the email in a web view that doesn't support the deep link.

Documentation: Document this process to ensure future developers understand the modifications made.

Conclusion

By customizing the token validation and deep linking mechanisms of Flask Security, you can create a seamless password reset experience within your mobile app. Although it may not be a clean solution and requires some workarounds, it’s certainly achievable.

Keep experimenting with deep links and routing within your app to enhance user interactio