How to Fix the Invalid Authenticity Token Error in Rails from an External Form

Learn how to resolve the `invalid authenticity token` error when sending form data from an external WordPress page to a Rails application. --- This video is based on the question https://stackoverflow.com/q/66142424/ asked by the user 'Adam' ( https://stackoverflow.com/u/14668403/ ) and on the answer https://stackoverflow.com/a/66142729/ provided by the user 'Chris Farmer' ( https://stackoverflow.com/u/404/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions. Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to solve invalid authenticity token error in Rails when sending form data from external page Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/licensing The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license. If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com. --- How to Fix the Invalid Authenticity Token Error in Rails from an External Form If you've ever encountered the frustrating invalid authenticity token error while trying to send form data from an external page to your Ruby on Rails application, you're not alone. This is a common issue, especially when dealing with forms on platforms like WordPress that need to communicate with a Rails backend. In this guide, we'll explore why this error arises and provide a clear solution to help you move forward seamlessly. Understanding the Authenticity Token Concept Before diving into the solution, it’s essential to understand what the authenticity token is and why it exists in Rails applications. The authenticity token is a security feature used to prevent Cross-Site Request Forgery (CSRF) attacks. Rails automatically generates a unique token for every session, and this token must be included with any form submission to verify that the request is legitimate. When you send a form from an external page, such as a WordPress site, the Rails application expects to see a valid authenticity token. If that token is missing or invalid, Rails raises the invalid authenticity token error, effectively blocking the request to protect against potential attacks. Solution: Disabling Authenticity Token Verification In scenarios where you are sending data from an external application (like WordPress) to your Rails application, you might not care much about CSRF protection for that specific action. Thus, you can bypass the authenticity token requirements for your controller action. Here’s how to do that: Steps to Disable Authenticity Token Verification Locate Your Controller: Open the Rails controller that handles the action for the form submission. Add the skip_before_action directive: You'll want to include the following line inside your controller class: [[See Video to Reveal this Text or Code Snippet]] Replace :your_wordpress_action with the actual name of the action that processes the data sent from your WordPress page. By doing this, you instruct Rails to skip the CSRF token verification for that specific action, allowing the request to proceed without encountering the invalid authenticity token error. Important Considerations While disabling authenticity token verification can help you bypass the immediate issue, keep these considerations in mind: Security Implications: Disabling CSRF protection can expose your application to vulnerabilities. Use this option judiciously, and only for actions that do not require high security. Alternative Solutions: If security is a concern or if the external form supports including an authenticity token, consider managing tokens more robustly. This could involve generating a token from Rails and passing it to the external page, though this can add complexity. Conclusion Encountering an invalid authenticity token error when posting form data from an external page to your Rails application can be frustrating. However, by disabling the authenticity token verification for the relevant controller action, you can continue to develop your application without this hindrance. Just remember to weigh the security implications carefully and consider your options before choosing the best path forward. With this knowledge in hand, you can now effectively manage form submissions across different platforms. Happy coding!