Log when rescue_from handles an exception #55389
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In development when a `before_action` renders or redirects this error
message appears on the logs:
> Filter chain halted as :before_action rendered or redirected
I find this message very helpful. However, if a before_action raises an
error that is handled by a rescue_from block, nothing is logged
indicating an error occurred.
This PR adds a log message indicating an exception was rescued, and
displays where it was originally raised. For example:
> rescue_from handled exception HomeController::MyError("Oh no!") -
> /home/vscode/my-test-app/app/controllers/home_controller.rb:15:in
> 'HomeController#authenticate'
byroot
reviewed
Jul 23, 2025
| @@ -92,6 +92,7 @@ def rescue_with_handler(exception, object: self, visited_exceptions: []) | |||
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| if handler = handler_for_rescue(exception, object: object) | |||
| handler.call exception | |||
| logger.info("rescue_from handled exception #{exception.class} (#{exception.message}) - #{exception.backtrace.first}") | |||
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I think the feature makes sense, but this isn't the proper way to implement it.
The log should be in actionpack/lib/action_controller/log_subscriber.rb, and here it should just fire an ActiveSupport::Notification.
You can look at def halted_callback_hook for inspiration.
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Thanks @byroot. I'll check it out.
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Motivation / Background
In development when a
before_actionrenders or redirects this error message appears on the logs:I find this message very helpful. However, if a before_action raises an error that is handled by a rescue_from block, nothing is logged indicating an error occurred.
Original proposal
Detail
This PR adds a log message indicating an exception was rescued, and displays where it was originally raised. For example:
Checklist
Before submitting the PR make sure the following are checked:
[Fix #issue-number]