On 7/13/09 7:59 AM, Alberto Valverde wrote:
> Hello,
>
> I'm factoring out the core logic of a bunch of views into a generic CRUD
> "controller" for a bfg app which looks something like this:
>
> class GenericCrud(..):
> def __init__(self, bunch of configuration options):
> # update __dict__ with these options and some derived ones
>
> def member_view(self, context, request):
> # dispatch to helper method on HTTP method
>
> def collection_view(self, context, request):
> # ditto
>
> # collection_view dispatches to this on POST
> def create(self, context, request):
> # just a normal view function but have settings and helper (quite
> possibly overridden)
> # methods accessible at 'self'. The instance is *never* modified here
>
> # member_view to this on PUT
> def update(...): ...
>
> which is used like this:
>
> # some_views.py, module scope:
> class UserCrud(GenericCrud):
> # some template methods implemented
>
> # Instantiate a module-scope (stateless) singleton
> user_crud = UserCrud(some overrides like grid columns, form fields, etc...)
>
> # Now the work-arounds so the views can be registered I'd like to get
> rid of,
> # I'll explain below.
> user_member_view = user_crud.member_view
> user_collection_view = user_crud.collection_view
>
> This is wired up into the ZCA registry like this, configure.zcml:
>
> <view
> for=".interfaces.IUsers"
> view=".views.user.user_config_view"
> name="config.js"
> permission="view"
> />
> <view
> for=".interfaces.IUsers"
> view=".views.user.user_collection_view"
> request_type="GET"
> permission="view"
> />
> <view
> for=".interfaces.IUsers"
> view=".views.user.user_collection_view"
> request_type="POST"
> permission="create"
> />
> <view
> for=".interfaces.IUser"
> view=".views.user.user_member_view"
> request_type="GET"
> permission="view"
> />
> <view
> for=".interfaces.IUser"
> view=".views.user.user_member_view"
> request_type="PUT"
> permission="update"
> />
> <view
> for=".interfaces.IUser"
> view=".views.user.user_member_view"
> request_type="DELETE"
> permission="delete"
> />
>
> Ok, the above zcml sucks a bit right now in the terseness department
> since there needs to be a directive for each request_type just to
> declare permissions (it wouldn't be needed otherwise since the
> "controller" takes care of dispatching) but I'll eventually write my
> custom zcml directive-processors which will take care of the
> bolier-plate when I find some time to learn how-to.
Right.
>
> Anyway, I'd like to remove the work-arounds I mentioned (the user_*_view
> aliases at module-scope) since the "view" directive doesn't seem able to
> import an instancemethod (or any non-module-global for that matter, I
> think).
Yes, the resolver won't descend past module scope to find names.
> They're not too bad at the moment but it will soon be when I
> wire up all the exposed domain models....
>
> Would this be possible or even desirable? Is there a better pattern to
> do this kind of "pre-configured" views that someone can share? I'd
> happily send a patch for this with tests, just point me in the right
> direction (I'm still mapping the repoze.* namespace in my head...).
I'm not sure if this helps, but instead of making a view out of an
instancemethod with a special name, maybe you could make N view classes, one
for
each alias you currently have:
class UserCrud(GenericCrud):
def __init__(self, context, request):
self.context = context
self.request = request
class UserMemberView(UserCrud):
def __call__(self):
... do member-related dispatching ...
... return response ..
class UserCollectionView(UserCrud):
def __call__(self):
... do collection-related dispatching ...
... return response ..
then in ZCML:
<view
for=".interfaces.IUsers"
view=".views.user.UserCollectionView"
request_type="GET"
permission="view"
/>
<view
for=".interfaces.IUsers"
view=".views.user.UserCollectionView"
request_type="POST"
permission="create"
/>
<view
for=".interfaces.IUser"
view=".views.user.UserMemberView"
request_type="GET"
permission="view"
/>
<view
for=".interfaces.IUser"
view=".views.user.UserMemberView"
request_type="PUT"
permission="update"
/>
<view
for=".interfaces.IUser"
view=".views.user.UserMemberView"
request_type="DELETE"
permission="delete"
/>
> I've already evaluated using a class as a view [1] but having the
Aw you left us hanging.
> PS: I'm having *a lot* of fun with bfg! Big thanks for extracting all
> these zope gems (and the non-zope ones you've created) into easily
> digestible eggs for the rest of us. :)
Thanks for the feedback!
- C
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