Communicate request body validation errors to the client

[sawa-ko]

I don't know how to report validation errors that have occurred when trying to use a controller, as currently only the message “Bad request” is displayed but this does nothing to help solve the problem of why the request could not be processed.

Actually I see that the validation error does appear in the logs of the application, and I was wondering if there is a way to serialize the validation error that appears in the logs so that it is shown in the error message received by the client that uses the controller that gave error.

If this error message could be transmitted, the client consuming the controller would know how to correctly send the body expected by the controller.

[avk458]

Because the scaffold controller uses the loco_rs::Result type alias, the code in controller.rs turns every other error into a bad request.
You can create an error type and implement IntoResponse as you like.