django - Show error message when decorator fails -

the decorator working fine display error message (i'd use messages framework) if user doesn't belong of required groups. here's decorator:

def group_required(*group_names):     """requires user membership in @ least 1 of groups passed in."""     def in_groups(user):         if user.is_authenticated():             if bool(user.groups.filter(name__in=group_names)) or user.is_superuser:                 return true         return false     return user_passes_test(in_groups) 

i call using like:

@require_http_methods(['get'])     @group_required('supervisor') def home_view(request):     return render(request, 'home.html') 

i tried using snippet use messages framework (since requires request object) realized messages framework middleware didn't appear installed inside decorator.

i'm willing change whatever takes :)

update:

what i'm looking for:

def group_required(request, *group_names):     """requires user membership in @ least 1 of groups passed in."""     def in_groups(user):         if user.is_authenticated():             if user.groups.filter(name__in=group_names).exists() or user.is_superuser:                 return true             else:                 # i'm getting:                 # cannot add messages without installing django.contrib.messages.middleware.messagemiddleware                 messages.add_message(request, messages.error, 'group not allowed')         return false     return user_passes_test(in_groups, request) 

i don't think need threadlocals in use case. , when threadlocals seems way go in django app, there mis-structured context layers. comparing w/ threadlocals, rather duplicate user_passes_test , modify pass request in_groups (we not pass request is_group without modifying code of user_passes_test. check question: how pass django request object in user_passes_test decorator callable function.) (maybe ticket this?)

furthermore, bool(user.groups.filter(name__in=group_names)) caused items retrieved db adapter , python instance before deciding existence, using exists() , user.groups.filter(name__in=group_names).exists() directly return bool result db backend far more efficient here.