django/shortcuts/__init__.py

   1 """
   2 This module collects helper functions and classes that "span" multiple levels
   3 of MVC. In other words, these functions/classes introduce controlled coupling
   4 for convenience's sake.
   5 """
   6
   7 from django.template import loader
   8 from django.http import HttpResponse, Http404
   9 from django.db.models.manager import Manager
  10 from django.db.models.query import QuerySet
  11
  12 def render_to_response(*args, **kwargs):
  13     """
  14     Returns a HttpResponse whose content is filled with the result of calling
  15     django.template.loader.render_to_string() with the passed arguments.
  16     """
  17     httpresponse_kwargs = {'mimetype': kwargs.pop('mimetype', None)}
  18     return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs)
  19
  20 def _get_queryset(klass):
  21     """
  22     Returns a QuerySet from a Model, Manager, or QuerySet. Created to make
  23     get_object_or_404 and get_list_or_404 more DRY.
  24     """
  25     if isinstance(klass, QuerySet):
  26         return klass
  27     elif isinstance(klass, Manager):
  28         manager = klass
  29     else:
  30         manager = klass._default_manager
  31     return manager.all()
  32
  33 def get_object_or_404(klass, *args, **kwargs):
  34     """
  35     Uses get() to return an object, or raises a Http404 exception if the object
  36     does not exist.
  37
  38     klass may be a Model, Manager, or QuerySet object. All other passed
  39     arguments and keyword arguments are used in the get() query.
  40
  41     Note: Like with get(), an MultipleObjectsReturned will be raised if more than one
  42     object is found.
  43     """
  44     queryset = _get_queryset(klass)
  45     try:
  46         return queryset.get(*args, **kwargs)
  47     except queryset.model.DoesNotExist:
  48         raise Http404('No %s matches the given query.' % queryset.model._meta.object_name)
  49
  50 def get_list_or_404(klass, *args, **kwargs):
  51     """
  52     Uses filter() to return a list of objects, or raise a Http404 exception if
  53     the list is empty.
  54
  55     klass may be a Model, Manager, or QuerySet object. All other passed
  56     arguments and keyword arguments are used in the filter() query.
  57     """
  58     queryset = _get_queryset(klass)
  59     obj_list = list(queryset.filter(*args, **kwargs))
  60     if not obj_list:
  61         raise Http404('No %s matches the given query.' % queryset.model._meta.object_name)
  62     return obj_list