You need to make a new formlet that knows about the default values.<div><br></div><div>We could imagine a macro that makes this nicer, but in general it will need to be something that creates a new one.</div><div><br></div> <div>Is there some reason you don't want to do that?</div><div><br></div><div>I can imagine something like (formlet-display) that took the old values, but then it would be more monad-like than arrow-like, and wouldn't really be a formlet. If you can clarify your use case, it may be worth investigating.</div> <div><br></div><div>Jay<br><br><div class="gmail_quote">On Fri, Nov 18, 2011 at 1:13 PM, Jordan Schatz <span dir="ltr"><<a href="mailto:jordan@noionlabs.com">jordan@noionlabs.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"> <br> I have a pattern of user interaction that is common in my web app:<br> <br> I have a db record, I present it to the user in a form, the user edits<br> the form, submits it, server side logic validates it, and then returns<br> the same form with the updated record.<br> <br> I want to port the app to Racket, and I thought formlets would be just<br> the thing, but I don't see how to fill the values into the formlet<br> without making a new formlet... seems I need a (formlet-fill<br> (some-values)) to go along with the formlet-display and formlet-process.<br> <br> Here is what I have: (Which doesn't work)<br> <br> ----------------------------------------------------------------------<br> #lang web-server/insta<br> <br> (require web-server/formlets)<br> <br> (define record (hasheq 'title "this is a title"<br> 'body "post body"))<br> <br> (define (start request)<br> (edit-record request))<br> <br> (define (edit-record request)<br> (local [(define (record-formlet our-values)<br> (formlet<br> (#%# ,{(text-input #:value (string->bytes/utf-8 (hash-ref our-values 'title))) . => . title}<br> ,{(text-input #:value (string->bytes/utf-8 (hash-ref our-values 'body))) . => . body})<br> (values title body)))<br> <br> (define (handle-response request)<br> (define-values (title body)<br> (formlet-process our-formlet request))<br> (set! record (hasheq 'title title<br> 'body body))<br> (start (redirect/get)))<br> <br> (define (response-generator embed/url)<br> (response/xexpr<br> `(html<br> (form ([action ,(embed/url handle-response)])<br> ,@(formlet-display our-formlet)<br> (input ([type "submit"]))))))]<br> <br> (send/suspend/dispatch response-generator)))<br> <br> ----------------------------------------------------------------------<br> <br> It seems like this would be a very common pattern... what is the "normal"<br> way to do it?<br> <br> Thanks,<br> Jordan<br> _________________________________________________<br> For list-related administrative tasks:<br> <a href="http://lists.racket-lang.org/listinfo/users" target="_blank">http://lists.racket-lang.org/listinfo/users</a><br> </blockquote></div><br><br clear="all"><div><br></div>-- <br>Jay McCarthy <<a href="mailto:jay@cs.byu.edu" target="_blank">jay@cs.byu.edu</a>><br>Assistant Professor / Brigham Young University<br><a href="http://faculty.cs.byu.edu/~jay" target="_blank">http://faculty.cs.byu.edu/~jay</a><br> <br>"The glory of God is Intelligence" - D&C 93<br> </div>