Allow any scheme?

[gravitystorm]

Is it possible to validate a url, without having to provide a pre-determined list of schemes?

The situation is that we are validating a :callback_url, for oauth applications registered on our site. Since the :callback_url can contain application-specific schemes (e.g. myapp://something), we don't know which schemes will be used and so we can't provide a list to the validator.

I've tried e.g. validates_url :callback, schemes: nil, and schemes: [], without success. Any workarounds would also be appreciated.

[mochetts]

I'm in the need of the same