Re: Operate upon POST request with Guile webserver

["Daniel Meißner" <daniel.meissner-i4k@ruhr-uni-bochum.de>]

Hi,

Am 17. August 2022 13:50:46 MESZ schrieb Gentoo Arch <gentoocore@firemail.cc>:
> Hi,
> 
> I'd like to ask for your advice.
> 
> I'm trying to figure out how Guile webserver works to develop a simple BBS  and I'm kinda stuck with POST request.
> 
> My Guile script generates a form on any path and the form sends to "/post" path, where I can easily render content sent by the form.
> 
> (define (show-page request body)
>   (if (equal? (get-path request) ; get-path is my other function to retrieve the path
>               '("post"))
>       (values '((content-type . (text/plain)))
>                body)
>       (respond ; literally a respond template from webserver doc
>        `((h1 "Oops!")
>      (p (@ (id "test")) "The path: " ,(get-path request))
>      (form (@ (method "POST") (action "/post"))
>            (label (@ (for "test")) "Content: ")
>            (input (@ (id "test") (type "text") (name "content")))
>            (input (@ (type "submit") (value "Submit"))))))))
> 
> But I would like to operate upon the content the form sends like web apps usually do: insert it in the database or simply write to file. So my question is how I can proceed with something like that:
> 
> (define tf (open-file "test-file.txt" "a"))
> 
> (define (show-page request body)
>   (if (equal? (get-path request)
>               '("post"))
>       ((values '((content-type . (text/plain)))
>               body)
>        (display body tf)); I'd like to write/append body to the file, but it does nothing
>       (respond
>        `((h1 "Oops!")
>      (p (@ (id "test")) "The path: " ,(get-path request))
>      (form (@ (method "POST") (action "/post"))
>            (label (@ (for "test")) "Content: ")
>            (input (@ (id "test") (type "text") (name "content")))
>            (input (@ (type "submit") (value "Submit"))))))))
> 
> If I remove (values), it does write to a file (with a complaint in webserver output), but I'd also like to add some kind of redirect from "/post" page after the script has written stuff to file and I can't use two functions per response.
> 
> Could you please advise how I can achieve this functionality?

I think you probably want to replace the true-branch of your `if' form with

(begin
  (display body tf)
  (values '((content-type . (text/plain)) body))

It is important that the handler returns two values, so the `values' form must come last in the sequence. These two return values make up the response.

Best
Daniel