Allow user to specify headers

[michaldarda]

Fixes #1

Hello @emq ;)

Hope you find it useful

Just one thing, I don't know it is just me or it is simply broken

  1) My Middleware logging without storage raises an error
     Failure/Error: expect { get '/' }.to raise_error(Rack::RequestPolice::NoStorageFound)
       expected Rack::RequestPolice::NoStorageFound but nothing was raised
     # ./spec/middleware_spec.rb:222:in `block (3 levels) in <top (required)

I also had to modify configuration in other specs, because class variables were cached between specs and test result were undetermistic.

[rwojsznis]

Hi Michał, long time no code

Thanks for the PR, looks neat 👍 it seems like this spec you mention passes on travis, oh boy 😁 will try to take a look before releasing new version on rubygems.

[rwojsznis]

Not a big fan of inline rescue - what's the reason behind it?

Can you give me real-world usage example please? I'm guessing there is more to it 😉

[michaldarda]

Well, me neither

But..

If user specifies wrong transformation, for example

{ |h| h.some_not_existing_method }

Seems reasonable to me, to rescue to original header_value if that transformation fails instead of returning 500 ;)

[rwojsznis]

We're transforming a string there, so personally I would rather get 500 instantly than to swallow exception silently (bad experience with too much rescue ) - but within current implementation this is indeed not possible - transformation is always called, even if header is missing (you transform nil, rescue it if something bad happens (that returns nil again) and then fallback to fallback value (I hope I didn't mess up anything, but it seems about right). It might be a personal taste, but I will allow myself to modify this a little 😉

Except that - thanks again for PR 👍 I hope I will manage to release new version this week, this is probably a good time to add a changelog too ;-).

Cheers ❤️

[rwojsznis]

note: was chilling in Slovakia, will try to release this upcoming week, sorry for the delay ;*