Скачать или смотреть Fixing the Method Not Allowed Error When Editing an Object in Spring + Thymeleaf

Learn how to resolve the common `HttpRequestMethodNotSupportedException` issue when trying to edit existing objects with Spring and Thymeleaf.
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This video is based on the question https://stackoverflow.com/q/68620431/ asked by the user 'decd' ( https://stackoverflow.com/u/13599662/ ) and on the answer https://stackoverflow.com/a/68620864/ provided by the user 'Dimitri Mestdagh' ( https://stackoverflow.com/u/1915448/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Fix Method Not Allowed Error While Editing Objects in Spring + Thymeleaf

If you're working with Spring and Thymeleaf to manage objects in your database, you might encounter a common issue when trying to edit existing objects. One user faced an error message indicating that their method was not allowed when attempting to save changes to an object. In this post, we will explore the problem in detail and provide a solution to this frustrating situation.

The Problem: Understanding the Error Message

The user reported the following error in their logger:

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

This error indicates that a POST request was made to an endpoint, /edit/save, which does not support that request method. In most applications, this typically happens when the URL specified in your form is incorrect.

The Cause of the Error

Upon reviewing the user's Thymeleaf template, we see that the form action was defined as follows:

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

The absence of a leading slash before save means Thymeleaf interprets this as a relative URL. When the form is submitted, it is actually trying to call /edit/save (appending save to the existing URL context), resulting in the Method Not Allowed error because, likely, that endpoint is not defined in the controller.

The Solution: Modify the Form Action

To fix the issue, we need to prepend a slash to the form action in the Thymeleaf template. This change tells the application to treat the URL as absolute rather than relative, directing the POST request to the correct endpoint:

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

Updated Thymeleaf Template Snippet

Here’s how the updated part of your form should look:

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

By making this change, the form will correctly submit to /save, and the Spring controller should be able to handle the POST request as intended.

Summary

When working with Spring and Thymeleaf, it's essential to ensure that your URL mappings are accurate, especially for form actions. This small but crucial adjustment can save you from hours of debugging. Whenever you run into similar issues, double-check your endpoint definitions and action attributes in your forms.

With these insights, you should be able to edit existing objects in your Spring application without further issues. Happy coding!