I discovered a problem with Zope 3 while developing ReSTive interfaces for schoolbell, which utilize the HTTPPublication and the HTTPRequestFactory.
When the user sends a request for a method that is not supported by the object, the HTTP spec (RFC 2616) mandates response code 405, Method Not Supported. This response must include an 'Allow' header listing all the methods allowed for this object.
Currently, in the generic case, Zope 3 raises a ComponentLookupError in zope.app.publication.http line 74, and a 500 response is served.
I can't find that particular line of code. Are you talking about HTTPPublication.callObject where it looks up the view (zapi.getMultiAdapter) which might result in a ComponentLookupError in case the adapter can't be looked up?
The obvious fix is to raise a special exception if a corresponding view is not found, which would have a view to return a 405 response:
class MethodNotAllowed(Exception): implements(IMethodNotAllowed)
def __init__(self, object, request): self.allow = [name for name, adapter in zapi.getAdapters((object, request), Interface) if hasattr(adapter, name)]
def __str__(self): return 'Allow: %s' % self.allow
def __init__(self, error, request): self.error = error self.request = request
def __call__(self): self.request.response.setHeader('Allow', ', '.join(self.error.allow)) self.request.response.setStatus(405) return 'Method Not Allowed'
This looks good. I'm +1 on this.
The problem with this approach is that there are DELETE and PUT views defined for "*", which try to adapt the container to IWriteDirectory, IFileFactory, or adapt an existing object to IWriteFile. So, such error view would advertise that PUT and DELETE are available on all objects.
If these methods are called on objects that do not have appropriate adapters, a TypeError is raised, with the 500 response.
Well, maybe that should change then. These views could easily raise MethodNotAllowed, couldn't they? If they can't find the necessary adapters, the their functionality is obviously not available and they should raise an appropriate error.
I believe correct 405 handling is the business of the HTTP publication machinery, the client apps should not worry about that.
Any ideas on how to proceed?
Your proposed solution sounds good to me.
Philipp _______________________________________________ Zope3-dev mailing list Zope3email@example.com Unsub: http://mail.zope.org/mailman/options/zope3-dev/archive%40mail-archive.com