Re: Questions about the (web client) module.

[Roel Janssen]

Hi Ludo’,

Thanks for your response.

Ludovic Courtès writes:

> Hi Roel,
>
> Roel Janssen <address@hidden> skribis:
>
>> When I use http-post, and I want to change the HTTP header called
>> "Content-Type", I seem to need to spell it as "content-type" in the
>> #:headers part of the 'http-post' section.  Other headers like "Accept"
>> do not seem to follow the same lowercase style route.
>>
>> More confusingly, using something like:
>>   #:headers '((Content-Type . "text/csv"))
>>
>> leads to outputting the "Content-Type" header twice.
>> Why is "content-type" special?
>
> ‘sanitize-request’ in (web client) adds a ‘Content-Type’ header if there
> is none.

But 'Content-Type' and 'content-type' is not the same.. Adding a
'Content-Type' header results in the request having two 'Content-Type'
headers.  So it doesn't add 'Content-Type' when it isn't there, it
converts 'content-type' to 'Content-Type', so it adds 'Content-Type'
when 'content-type' isn't there.  This seems wrong to me.

>
> As for lower-case, perhaps the ‘request’ procedure in (web client)
> should automatically convert to lower-case, or perhaps we should simply
> clarify the documentation here.

Or perhaps do not treat some HTTP headers different than others, and
just keep it 'Content-Type' (as used in HTTP) instead of 'content-type'.

>
>> Then my next question is about "multipart/form-data" content types.
>> My code looks like this:
>>
>>   #:headers `((content-type . ,(string-append
>>                                 "multipart/form-data; boundary=" boundary))
>>               (Accept . "*/*"))
>>
>> But that does not work:
>>   scheme@(guile-user)> 
>>   web/request.scm:184:10: In procedure build-request:
>>   web/request.scm:184:10: Bad request: Bad value for header content-type: 
>> "multipart/form-data; boundary=..."
>>
>> This is, however, a valid Content-Type.
>
> What’s the value of ‘boundary’?  At first sight it looks good to me:

The value I use is "guile-virtuoso-driver".  All of the below
functions work as expected with this value.

Could it be that something else is wrong?
Here's the entire code I use:

--8<---------------cut here---------------start------------->8---
(define* (sparql-query-post query
                       #:key
                       (host "localhost")
                       (port 8890)
                       (graph "")
                       (type "json"))
  (let ((base-uri (string-append "http://"; host ":" (number->string port) ))
        (boundary "guile-virtuoso-driver"))
    (let ((body (string-append
                 (format #f
                  "--~a~%Content-Disposition: form-data; name=~s~%~%text/csv~%"
                  boundary "format")
                  (format #f
                  "--~a~%Content-Disposition: form-data; name=~s~%~%~a~%--~a~%"
                  boundary "query" query boundary))))
      (http-post
       (string-append base-uri "/sparql")
       #:body body
       #:headers `((content-length . ,(string-length body))
                   (content-type . "multipart/form-data; 
boundary=guile-virtuoso-driver")
                   (Accept . "*/*"))))))
  (define %query-get-all-triplets
  "SELECT * FROM <http://localhost:8890/packages>
WHERE
{
  ?s ?p ?o
}")

(sparql-query-post %query-get-all-triplets)
--8<---------------cut here---------------end--------------->8---

Which results in:

--8<---------------cut here---------------start------------->8---
web/request.scm:184:10: In procedure build-request:
web/request.scm:184:10: Bad request: Bad value for header content-type: 
"multipart/form-data; boundary=guile-virtuoso-driver"
--8<---------------cut here---------------end--------------->8---

Thanks!

Kind regards,
Roel Janssen