[Twisted-web] How works formless?

[Donovan Preston]

On Jun 30, 2005, at 2:58 AM, Alberto Trujillo wrote:

> Hello:
> I was trying to follow this example but I'm a bit lost. I can see  
> the form but when I submit the information I receive the next  
> exepction error "global name request is not defined".
> I don't know why formless has to be autocallable and where I must  
> to defined "request"
>
> Could anybody help me? Here are my files. I need to know what I  
> have to do after submit the information.

If you are just starting with Nevow, I suggest staying away from  
formless for a while. It is designed for a very specific use case,  
and has some well-known problems which nobody has taken the time to fix.

> year.tac
> ----------
> from twisted.application import internet, service
> from nevow import appserver
> import year
>
> application = service.Application("tasks")
> webserver = internet.TCPServer(8080, appserver.NevowSite 
> (year.Colorful()))
> webserver.setServiceParent(application)
>
> year.py
> ---------
> from nevow import rend, loaders
> import formless
>
> class YearChooseable(formless.TypedInterface):
>    def selectYear(self, year=formless.Integer()):
>        pass
>    selectYear = formless.autocallable(selectYear)
>
>
> class Colorful(rend.Page):
>    __implements__ = YearChooseable, rend.Page.__implements__
>
>
>    def selectYear(self, year):
>        self.test = True
>        return rend.Page.locateChild(self, request, childSegments)

This line is very strange. autocallables don't normally return  
things, they normally just change object state. self.test = True is  
correct, but the line below it looks like it comes from an overridden  
locateChild method, which is totally inappropriate for a formless  
autocallable. Also, I don't think locateChild has ever taken a  
request argument; it has always taken a context argument. Remove this  
line and everything should work fine.

>    docFactory = loaders.xmlfile("year.html")
>
> year.html
> ----------
> <form action="freeform_post!!selectYear" method="POST">
>    Type a year: <input type="text" name="year" />
>    <input type="submit" />
> </form>

Donovan