I get that I need formlet-process somewhere, but what I wanted is to only know about it in the same function/closure where I am doing the rendering - which obviously works in the definition of embed-formlet above, since it embeds the url to format-process. I thought that embed-formlet would somehow store formlet-process in some table somewhere and then make it available in some shape once the URL gets hit, but now I see it's a simple closure.
What I want to achieve seems to be done by the following code: (define (debrief request) (define test-formlet (formlet (div "Name:" ,{input-string . => . name}) (list name))) (define (response-generator embed/url) (html-wrapper `((h1 "Testing Formlets") ,(embed-formlet embed/url test-formlet) ))) (define (testing result) (html-wrapper `((h1 "Result") (div ,(first result))))) (testing (send/suspend/dispatch response-generator))) with the exception that I want a submit button inside the form element, but that should be easy enough to solve. In short, I wanted to have the function `testing` to not need to be passed the formlet I defined, yet to receive the results. Thanks for solving the problem I had, if not the problem I stated. Cheers, Marc On Wed, Aug 23, 2017 at 3:39 PM, Jay McCarthy <jay.mccar...@gmail.com> wrote: > On Wed, Aug 23, 2017 at 8:26 AM, Marc Kaufmann > <marc.kaufman...@gmail.com> wrote: > > Hi again, > > > > I am now trying to deal with formlets in a more principled fashion and > thus > > trying to implement, as Philip suggested, to use `send/formlet` and > > `embed-formlet`. After a lot of tinkering, I still haven't figured out > how > > to actually process the formlet (without having to pass it around) with > > embed-formlet. Here is the current example: > > > > (define (debrief request) > > (define test-formlet > > (formlet > > (div "Name:" ,{input-string . => . name}) > > (list name))) > > (define (response-generator embed/url) > > (html-wrapper > > `((h1 "Testing Formlets") > > (form ([action ,(embed/url testing)] > > [method "POST"]) > > (p "Here is the displayed formlet") > > ;,@(formlet-display test-formlet) ;; THIS WORKS > > ,(embed-formlet embed/url test-formlet) > > (input ([type "submit"])) > > )))) > > > > The above works without `embed-formlet` with the following definition of > > `testing`: > > > > (define (testing request) > > (define result (formlet-process test-formlet request)) > > (html-wrapper > > `((h1 "Result") > > (div > > ,(first result))))) > > (send/suspend/dispatch response-generator)) > > > > But it does not work (or I can't figure out how it works) with > > embed-formlet. How do I process the formlet, with the requirement that I > do > > not want to refer explicitly to `test-formlet`? > > That is not possible. A formlet defines two things: the rendering and > the processing, so it doesn't make sense to process without the > processing definition. > > > Or is this not possible - in > > which case, what does `embed-formlet` do that `formlet-processing` > doesn't? > > Any working example with embed-formlet is appreciate, even if it is not > the > > same as mine. > > When you use embed-formlet, the formlet is displayed and when you > submit, then the formlet's processing runs and returns to the > call-site of send/suspend/dispatch. So you don't separate them. > embed-formlet is really simple: > > (define (embed-formlet embed/url f) > `(form ([action ,(embed/url > (lambda (r) > (formlet-process f r)))]) > ,@(formlet-display f))) > > > Thanks, > > Marc > > > > > > On Thu, Mar 16, 2017 at 2:11 PM, Marc Kaufmann < > marc.kaufman...@gmail.com> > > wrote: > >> > >> Thanks Philip. I checked out the links, but I fear that it's over my > head, > >> and that I would almost surely screw it up. For now I'll keep passing > the > >> parameters. > >> > >> Cheers, > >> Marc > >> > >> On Tuesday, March 14, 2017 at 3:22:39 PM UTC-4, Philip McGrath wrote: > >> > If you want it to be part of the continuation without having to pass > it > >> > around as an argument, check out web cells > >> > (http://docs.racket-lang.org/web-server/stateless.html?q= > web-server%2Flang%2Fwe#%28mod-path._web-server%2Flang%2Fweb-cells%29) > >> > or web parameters > >> > (http://docs.racket-lang.org/web-server/stateless.html?q= > web-server%2Flang%2Fwe#%28mod-path._web-server%2Flang%2Fweb-param%29). > >> > > >> > > >> > > >> > -Philip > >> > > >> > > >> > > >> > On Tue, Mar 14, 2017 at 1:48 PM, Marc Kaufmann <marc.ka...@gmail.com> > >> > wrote: > >> > > >> > > >> > > >> > Thanks for the detailed answer Philip! Some of it is definitely over > my > >> > head. The reason I don't pass around the id is that I use the html > field > >> > exactly to track the id and wanted to avoid having to pass around the > >> > argument left and right - and the only ways to pass it on are via > forms or > >> > by sticking it into the requested URL or by using continuations. I > will give > >> > the continuation-style solution a shot though, it's probably cleaner > to pass > >> > the id around as an argument. > >> > > >> > Cheers, > >> > Marc > >> > > >> > > >> > > >> > > >> > > >> > On Tue, Mar 14, 2017 at 1:34 PM, Philip McGrath > >> > <phi...@philipmcgrath.com> wrote: > >> > > >> > In this case it will work despite being a hack, because you know that > >> > your id argument affects only the display stage, not the processing > stage: > >> > however, you can't know in general that this will work for dynamically > >> > generated formlets, and personally I would therefore be reluctant to > rely on > >> > this, both because it is fragile in terms of changes to your > implementation > >> > of matrix-formlet that you might make later. > >> > > >> > > >> > If you are using native continuations (i.e. not the stateless #lang > >> > web-server), you can use send/formlet or embed-formlet to deal with > this > >> > correctly and easily. (At a lower level, you could also do something > >> > like(define-values (xexpr-forest bindings->result i) > >> > ((matrix-formlet "3") 0)) > >> > to access the low-level rendering, processing function, and next > >> > allowable input integer directly.) > >> > > >> > > >> > It is a little more tricky in #lang web-server, because your formlet > and > >> > it's generated processing function are plain functions, and thus not > >> > serializable (see this old thread for discussion: > >> > https://groups.google.com/d/topic/racket-users/lMYWjodgpmo/discussion). > The > >> > easy work-around is to keep the arguments you need to reproduce your > formlet > >> > around as part of the closure, e.g. by rewriting your > matrix-submission like > >> > this:(define (matrix-submission req id) > >> > (define-values (number-of-ones user-id) > >> > (formlet-process (matrix-formlet id) req)) > >> > ...) > >> > The alternative is to either recompile the formlet library using #lang > >> > web-server/base or to implement your formlet at a low level using > >> > serial-lambda and not use any of the library tools. > >> > > >> > > >> > In this specific case, though, if you are using this hidden input > field > >> > just to remember the user id from one request to the next (i.e. you > wouldn't > >> > ever change it on the client side with JavaScript or something), the > best > >> > solution is not to put it in the form at all, but have it be part of > the > >> > continuation. This could also have security advantages, if you > >> > cryptographically sign your continuations or store them on the > server. If > >> > that works for your use case, you could simply write: > >> > (define matrix-formlet > >> > > >> > input-string) > >> > display it with > >> > (matrix-submission > >> > (send/suspend > >> > (λ (k-url) > >> > (response/xexpr > >> > `(html (body (form > >> > ((action "/the-matrix-submitted") > >> > (method "post")) > >> > ,@(formlet-display matrix-formlet) > >> > (input ([type "submit"])))))))) > >> > user-id) > >> > and then define matrix-submission as(define (matrix-submission req > >> > user-id) > >> > (define number-of-ones > >> > (formlet-process matrix-formlet req)) > >> > ...) > >> > > >> > > >> > > >> > -Philip > >> > > >> > > >> > > >> > > >> > > >> > On Tue, Mar 14, 2017 at 12:01 PM, Marc Kaufmann <marc.ka...@gmail.com > > > >> > wrote: > >> > > >> > > >> > Hi, > >> > > >> > > >> > > >> > I have created a formlet like so: > >> > > >> > > >> > > >> > (define (matrix-formlet id) > >> > > >> > (formlet > >> > > >> > (#%# ,{input-string . => . ones} > >> > > >> > ,{(to-string (required (hidden id))) . => . user-id} > >> > > >> > ) > >> > > >> > (values ones user-id))) > >> > > >> > > >> > > >> > I display this as follows: > >> > > >> > > >> > > >> > `(form > >> > > >> > ((action "/the-matrix-submitted") > >> > > >> > (method "post")) > >> > > >> > ,@(formlet-display (matrix-formlet user-id)) > >> > > >> > (input ([type "submit"])))) > >> > > >> > > >> > > >> > and process it like this: > >> > > >> > > >> > > >> > (define (matrix-submission req) > >> > > >> > (define-values (number-of-ones user-id) > >> > > >> > (formlet-process (matrix-formlet "3") req)) > >> > > >> > ...) > >> > > >> > > >> > > >> > While this works, the formlet I use to display and process are not > >> > really the same, since they are created on the spot, and created with > >> > different parameters. So far it seems to work, but I am worried that > this > >> > will break down, and clearly this isn't the right way to go about > creating > >> > parametrizable formlets. > >> > > >> > > >> > > >> > The questions are (i) is the above going to work despite being a hack, > >> > and (ii) is there a correct and easy way to do the same thing? > >> > > >> > > >> > > >> > Cheers, > >> > > >> > Marc > >> > > >> > > >> > > >> > -- > >> > > >> > You received this message because you are subscribed to the Google > >> > Groups "Racket Users" group. > >> > > >> > To unsubscribe from this group and stop receiving emails from it, send > >> > an email to racket-users...@googlegroups.com. > >> > > >> > For more options, visit https://groups.google.com/d/optout. > >> > > > > -- > > You received this message because you are subscribed to the Google Groups > > "Racket Users" group. > > To unsubscribe from this group and stop receiving emails from it, send an > > email to racket-users+unsubscr...@googlegroups.com. > > For more options, visit https://groups.google.com/d/optout. > > > > -- > -=[ Jay McCarthy http://jeapostrophe.github.io ]=- > -=[ Associate Professor PLT @ CS @ UMass Lowell ]=- > -=[ Moses 1:33: And worlds without number have I created; ]=- > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. 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