django1/django/core/extensions.py

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# This module collects helper functions and classes that "span" multiple levels
# of MVC. In other words, these functions/classes introduce controlled coupling
# for convenience's sake.
from django.core.exceptions import Http404, ImproperlyConfigured, ObjectDoesNotExist
from django.core.template import Context, loader
from django.conf.settings import TEMPLATE_CONTEXT_PROCESSORS
from django.utils.httpwrappers import HttpResponse
_standard_context_processors = None
# This is a function rather than module-level procedural code because we only
# want it to execute if somebody uses DjangoContext.
def get_standard_processors():
global _standard_context_processors
if _standard_context_processors is None:
processors = []
for path in TEMPLATE_CONTEXT_PROCESSORS:
i = path.rfind('.')
module, attr = path[:i], path[i+1:]
try:
mod = __import__(module, '', '', [attr])
except ImportError, e:
raise ImproperlyConfigured, 'Error importing request processor module %s: "%s"' % (module, e)
try:
func = getattr(mod, attr)
except AttributeError:
raise ImproperlyConfigured, 'Module "%s" does not define a "%s" callable request processor' % (module, attr)
processors.append(func)
_standard_context_processors = tuple(processors)
return _standard_context_processors
def render_to_response(*args, **kwargs):
return HttpResponse(loader.render_to_string(*args, **kwargs))
load_and_render = render_to_response # For backwards compatibility.
def get_object_or_404(mod, **kwargs):
try:
return mod.get_object(**kwargs)
except ObjectDoesNotExist:
raise Http404
def get_list_or_404(mod, **kwargs):
obj_list = mod.get_list(**kwargs)
if not obj_list:
raise Http404
return obj_list
class DjangoContext(Context):
"""
This subclass of template.Context automatically populates itself using
the processors defined in TEMPLATE_CONTEXT_PROCESSORS.
Additional processors can be specified as a list of callables
using the "processors" keyword argument.
"""
def __init__(self, request, dict=None, processors=None):
Context.__init__(self, dict)
if processors is None:
processors = ()
else:
processors = tuple(processors)
for processor in get_standard_processors() + processors:
self.update(processor(request))
# PermWrapper and PermLookupDict proxy the permissions system into objects that
# the template system can understand.
class PermLookupDict:
def __init__(self, user, module_name):
self.user, self.module_name = user, module_name
def __repr__(self):
return str(self.user.get_permission_list())
def __getitem__(self, perm_name):
return self.user.has_perm("%s.%s" % (self.module_name, perm_name))
def __nonzero__(self):
return self.user.has_module_perms(self.module_name)
class PermWrapper:
def __init__(self, user):
self.user = user
def __getitem__(self, module_name):
return PermLookupDict(self.user, module_name)