1 files changed, 62 insertions, 0 deletions
diff --git a/webapp/django/shortcuts/__init__.py b/webapp/django/shortcuts/__init__.py
new file mode 100644
index 0000000000..1cece7c7c0
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+++ b/webapp/django/shortcuts/__init__.py
@@ -0,0 +1,62 @@
+"""
+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.template import loader
+from django.http import HttpResponse, Http404
+from django.db.models.manager import Manager
+from django.db.models.query import QuerySet
+
+def render_to_response(*args, **kwargs):
+    """
+    Returns a HttpResponse whose content is filled with the result of calling
+    django.template.loader.render_to_string() with the passed arguments.
+    """
+    httpresponse_kwargs = {'mimetype': kwargs.pop('mimetype', None)}
+    return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs)
+
+def _get_queryset(klass):
+    """
+    Returns a QuerySet from a Model, Manager, or QuerySet. Created to make
+    get_object_or_404 and get_list_or_404 more DRY.
+    """
+    if isinstance(klass, QuerySet):
+        return klass
+    elif isinstance(klass, Manager):
+        manager = klass
+    else:
+        manager = klass._default_manager
+    return manager.all()
+
+def get_object_or_404(klass, *args, **kwargs):
+    """
+    Uses get() to return an object, or raises a Http404 exception if the object
+    does not exist.
+
+    klass may be a Model, Manager, or QuerySet object. All other passed
+    arguments and keyword arguments are used in the get() query.
+
+    Note: Like with get(), an MultipleObjectsReturned will be raised if more than one
+    object is found.
+    """
+    queryset = _get_queryset(klass)
+    try:
+        return queryset.get(*args, **kwargs)
+    except queryset.model.DoesNotExist:
+        raise Http404('No %s matches the given query.' % queryset.model._meta.object_name)
+
+def get_list_or_404(klass, *args, **kwargs):
+    """
+    Uses filter() to return a list of objects, or raise a Http404 exception if
+    the list is empty.
+
+    klass may be a Model, Manager, or QuerySet object. All other passed
+    arguments and keyword arguments are used in the filter() query.
+    """
+    queryset = _get_queryset(klass)
+    obj_list = list(queryset.filter(*args, **kwargs))
+    if not obj_list:
+        raise Http404('No %s matches the given query.' % queryset.model._meta.object_name)
+    return obj_list