How to pass custom reason to 'write_error' through 'raise tornado.web.HTTPError(...)'?

[mrtn]

I want to use 'raise tornado.web.HTTPError(400, reason='invalid request')' to pass a custom reason to the error response, and I hope to do this by overriding 'write_error (self, status_code, **kwargs)' method.

But it seems that I can only access 'self._reason' inside 'write_error', which is not what I want. I also tried `kwargs['reason'] but that does not exist.

Any suggestion?

[Ben Darnell]

The exception that exposed the error is available to write_error as an exc_info triple in the keyword arguments. You can access the reason field with something like this:

    if "exc_info" in kwargs:

      e = kwargs["exc_info"][1]

      if isinstance(e, tornado.web.HTTPError):

          reason = e.reason

But note that the "reason" field is essentially deprecated (it is not present in HTTP/2), so it's probably not the best way to do whatever you're trying to do here (HTTPError's log_message field is a little better, but still not ideal). Just raise your own exception instead of using HTTPError; your write_error override can use `self.set_status(400)` when it sees the right kind of exception.

-Ben

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[mrtn]

I see. So basically I check for my own custom exception inside 'write_error' by doing 'if isinstance(e, MyOwnException):', and set the status and use whatever message in the exception there.

Thanks for the suggestions!