Are response headers returned by HTTP client expected to be flat or not?

[ostrolucky]

Hi, I'm building PSR-18 adapter for stripe-php and it's unclear if Stripe\HttpClient\ClientInterface::request method should return flat list of headers, or PSR-7 style headers where headers with multiple values are grouped under same key as another array value. So basically, should list of headers be array<string, string>, or array<string, list<string>>?

My confusion lies because your test cases assert for flat values

stripe-php/tests/Stripe/HttpClient/CurlClientTest.php

Line 339 in fd57205

$this->assertSame('req_123', $rheaders['request-id']);

but your code expects multi dimensional list

stripe-php/lib/ApiRequestor.php

Line 382 in fd57205

$rheaders['request-id'][0],

And as far as I can see, the code given is the only time your library happens to read response headers.

[ctrudeau-stripe]

Hello @ostrolucky, as far as we can tell it is always flat. This alerted us to a bug in our telemetry reporting. Thank you for pointing it out!

[ostrolucky]

Alright. And what's the expectation when server returns multiple values for same header name? Eg.

Set-Cookie: PHPSESSID=abc; path=/
Set-Cookie: PHPSESSID=def; path=/
Set-Cookie: PHPSESSID=ghi; path=/
Link: </2012/07/26/csstests/csshttplink.css>;rel=stylesheet
Link: </>;rel=next

[richardm-stripe]

The current behavior seems to be that it sets the value equal to the last header specified.

[ostrolucky]

Alright thx, I'll make my adapter to behave same way