On Tue, 2009-06-30 at 06:19 -0400, Chris McDonough wrote:
> On 6/30/09 1:39 AM, Iain Duncan wrote:
> >> Let's imagine a view "pets":
> >>
> >> from webob import Response
> >>
> >> def pets(context, request):
> >> return Response ('OK')
> >>
> >> when a URL comes in that is for a paricular pet:
> >>
> >> from webob import Response
> >>
> >>
> >> def pets(context, request):
> >> if request.subpath:
> >> petnum = request.subpath[0]
> >> return Response('OK with petnum %s' % petnum)
> >> return Response ('OK')
> >>
> >> when a URL comes in with a particular action for a pet:
> >>
> >> from webob import Response
> >> from repoze.bfg.chameleon_zpt import render_template_to_response
> >>
> >> def pets(context, request):
> >> if len(request.subpath) == 1:
> >> petnum = request.subpath[0]
> >> return Response('OK with petnum %s' % petnum)
> >> elif request.subpath == 2:
> >> petnum, action = request.subpath
> >> return render_request_to_response('%s.html' % action,
> >> petnum = petnum)
> >> return Response ('OK')
> >>
> >> That's at least one way to handle it. Another way is to register a view
> >> for
> >> "edit.html" against a "Pet" model.
> >
> > Thanks Chris, the latter is what I was thinking of. So, another
> > question, can the *context* object be a *class* instead of an instance?
> >
> > IE, can the class Pet be the context, such that a class level
> > __getitem__ returns the actual instance I'm after, and edit becomes the
> > view ( action ).
>
> This isn't a pattern that sounds familiar to me, sorry. The context is
> almost
> always an instance. It can be anything of course, but if it's a class it
> won't
> be traversed. If the class has a __getitem__, a TypeError will be raised
> because it will be called as an unbound method with a single argument.
>
> If I needed to do this, personally, I'd probably use traversal. I'd create a
> "root factory" (passed into "make_app" as the first argument) that when
> called
> with an environ returned an instance of some root object. The root object
> would
> have a __getitem__ that, given the identifier "pets" would return a Pets
> object.
> The Pets object would have a __getitem__ that, given an identifier,
> returned a
> "Pet" object representing that particular pet. Then I'd register a default
> view
> against the Pets object and both a default view and an "edit" view against
> the
> Pet object.
Thanks for the clarification, that's what I tried last night, ( called
the top one PetContextFactory ). The problem I hit was that if the PCF
is the end of the traversal, then the context should be a list of pets,
but if it isn't, then there's no need to fetch all the pets from the db.
So I think you're right, I should try url dispatch. I mostly wanted to
try it with traversal first to wrap my end around Zope style traversal
and see what I came up with.
Thanks
Iain
>
> That's because I've been using traversal for ten years and it's natural to
> me.
> It's not very natural for most folks. It sounds like you're more used to
> "url
> dispatch". In that case, were I you, I'd forget about traversal entirely and
> create a few routes in the form:
>
> "pets"
> "pets/:id"
> "pets/:id/edit"
>
> e.g.
>
> <route
> name="pets"
> path="pets"
> view=".views.pets_view"
> />
>
> ... etc ...
>
> Each one of these would go to a separate view that did the needful.
>
> - C
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