#16931: "get_context_data" should follow MRO
-------------------------+-------------------------------
Reporter: linovia | Owner: nobody
Type: New feature | Status: new
Milestone: | Component: Generic views
Version: 1.3 | Severity: Normal
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------+-------------------------------
Actually, mixins do not allow to cumulate the context building.
For example:
class CommentMixin(FormMixin, SingleObjectMixin):
pass
In that case, we expect both FormMixin and SingleObjectMixin to build
their context.
However, as none of them use super in their get_context_data do use super,
we only get the FormMixin context.
The reason to use super here is not to call the parent get_context_data
but the next class in MRO.
{{{
class A(object):
def a(self):
print "A"
if hasattr(super(A, self), 'a'):
super(A, self).a()
class B(object):
def a(self):
print "B"
if hasattr(super(B, self), 'a'):
super(B, self).a()
class C(object):
def a(self):
print "C"
class D(B, A):
pass
class E(C, A):
pass
print "MRO:", [x.__name__ for x in D.__mro__]
d = D()
d.a()
print "MRO:", [x.__name__ for x in E.__mro__]
e = E()
e.a()
}}}
With that example, one can see that d calls both B then A while e only
calls C.
While this might usually be unnoticed, it prevents Mixin to be chained.
For example, mixing a single object item with a list (for a shop: one
category with the associated products, for a bug tracker: a milestone with
the associated tickets) or a single item with a form such as a post with a
comment form.
--
Ticket URL: <https://code.djangoproject.com/ticket/16931>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To post to this group, send email to django-updates@googlegroups.com.
To unsubscribe from this group, send email to
django-updates+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/django-updates?hl=en.
