Added Request-ID to API calls.

[joshluongo]

I needed to get access to the Request-ID that is sent from the API for a project I was working on.

In order to make this work I have made two small changes.

• The Request-ID is stored in the RequestOptions as $requestId.
• In order to access $requestId I have added added basic check to the magic method in StripeObject.

You can access it by getting _requestid from any stripe object.

I hope this comes in handy for someone!

[bkrausz]

I agree that we should have a way to get response headers, but I don't think storing it on RequestOptions is the right way to expose it: they are meant to be sent per-request, and are fairly independent from the response. For example, they get glued through to future requests (ex: calling retrieve and then save uses the same RequestOptions by default, though I believe it does make a new options object).

I think I'd rather expose a getLastResponseHeaders accessor on each object, that is overridden on each refresh. Then we wouldn't need the _ key magic, and it's relatively clear that each refresh will update it. It also covers all headers, so things like Stripe-Version would be fetchable as well.

The other option would be a static method on ApiRequestor that does the same thing, but static methods are less appealing.

@kyleconroy - any thoughts on this?

[joshluongo]

@bkrausz I agree with you, My method is not the right way to achieve this, I needed the functionality asap for my implementation so it met my requirements.

I think having getLastResponseHeaders would be a worthwhile change to make.

[kyleconroy]

@bkrausz I think we should probably make this more generic by adding a getResponse method that returns the actually API response, status code, body and all.

[kyleconroy]

See the work done in #206