[racket] formlet-fill

From: Jordan Schatz (jordan at noionlabs.com)
Date: Fri Nov 18 15:13:35 EST 2011

I have a pattern of user interaction that is common in my web app:

I have a db record, I present it to the user in a form, the user edits
the form, submits it, server side logic validates it, and then returns
the same form with the updated record.

I want to port the app to Racket, and I thought formlets would be just
the thing, but I don't see how to fill the values into the formlet
without making a new formlet... seems I need a (formlet-fill
(some-values)) to go along with the formlet-display and formlet-process.

Here is what I have: (Which doesn't work)

#lang web-server/insta

(require web-server/formlets)

(define record (hasheq 'title "this is a title"
                       'body "post body"))

(define (start request)
  (edit-record request))

(define (edit-record request)
  (local [(define (record-formlet our-values)
             (#%# ,{(text-input #:value (string->bytes/utf-8 (hash-ref our-values 'title))) . => . title}
                  ,{(text-input #:value (string->bytes/utf-8 (hash-ref our-values 'body))) . => . body})
             (values title body)))

          (define (handle-response request)
            (define-values (title body)
              (formlet-process our-formlet request))
            (set! record (hasheq 'title title
                                 'body body))
            (start (redirect/get)))

          (define (response-generator embed/url)
               (form ([action ,(embed/url handle-response)])
                     ,@(formlet-display our-formlet)
                     (input ([type "submit"]))))))]
          (send/suspend/dispatch response-generator)))


It seems like this would be a very common pattern... what is the "normal"
way to do it?


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