twisted.web.resource.Resource.allowedMethods doesn't determine what methods are allowed

	@washort reported
Trac ID	trac#4958
Type	defect
Created	2011-03-15 19:20:44Z

Resource.render only consults allowedMethods after looking for a render_ method. If a render_FOO method exists, it's invoked; allowedMethods is only used to populate the Allow header in the response.

To quote wsanchez from #3684:

OK, so with this API, if you have `allowedMethods = ["GET"]`, then even though you are telling us that you don't want to allow HEAD (for whatever reason), we're going to ignore you and allow it anyway.

This strikes me as strangely inconsistent/exceptional API, so that bothers me. What I would prefer is that if you say allowedMethods = ["GET", "HEAD"], but you don't implement the HEAD method, then we'll use your GET implementation to provide HEAD.

That is, we should do what you ask us to do, and not pretend that we know better.

trac-id__4958 4958
type__defect defect
reporter__washort washort
priority__normal normal
milestone__ 
branch__ 
branch_author__ 
status__new new
resolution__None None
component__web web
keywords__ 
time__1300216844000000 1300216844000000
changetime__1300493988000000 1300493988000000
version__None None
owner__ 
cc__jknight

Start at twisted.web.resource.Resource.render, where the issue says allowedMethods is checked after render_ lookup. Trace how GET, HEAD, and other render methods are dispatched, then add coverage showing that allowedMethods controls which methods are accepted and that the Allow header matches the permitted methods.