philo/utils/__init__.py

   1 from django.db import models
   2 from django.contrib.contenttypes.models import ContentType
   3 from django.core.paginator import Paginator, EmptyPage
   4
   5
   6 def fattr(*args, **kwargs):
   7         """
   8         Returns a wrapper which takes a function as its only argument and sets the key/value pairs passed in with kwargs as attributes on that function. This can be used as a decorator.
   9
  10         Example::
  11
  12                 >>> from philo.utils import fattr
  13                 >>> @fattr(short_description="Hello World!")
  14                 ... def x():
  15                 ...     pass
  16                 ...
  17                 >>> x.short_description
  18                 'Hello World!'
  19
  20         """
  21         def wrapper(function):
  22                 for key in kwargs:
  23                         setattr(function, key, kwargs[key])
  24                 return function
  25         return wrapper
  26
  27
  28 ### ContentTypeLimiters
  29
  30
  31 class ContentTypeLimiter(object):
  32         def q_object(self):
  33                 return models.Q(pk__in=[])
  34
  35         def add_to_query(self, query, *args, **kwargs):
  36                 query.add_q(self.q_object(), *args, **kwargs)
  37
  38
  39 class ContentTypeRegistryLimiter(ContentTypeLimiter):
  40         """Can be used to limit the choices for a :class:`ForeignKey` or :class:`ManyToManyField` to the :class:`ContentType`\ s which have been registered with this limiter."""
  41         def __init__(self):
  42                 self.classes = []
  43
  44         def register_class(self, cls):
  45                 """Registers a model class with this limiter."""
  46                 self.classes.append(cls)
  47
  48         def unregister_class(self, cls):
  49                 """Unregisters a model class from this limiter."""
  50                 self.classes.remove(cls)
  51
  52         def q_object(self):
  53                 contenttype_pks = []
  54                 for cls in self.classes:
  55                         try:
  56                                 if issubclass(cls, models.Model):
  57                                         if not cls._meta.abstract:
  58                                                 contenttype = ContentType.objects.get_for_model(cls)
  59                                                 contenttype_pks.append(contenttype.pk)
  60                         except:
  61                                 pass
  62                 return models.Q(pk__in=contenttype_pks)
  63
  64
  65 class ContentTypeSubclassLimiter(ContentTypeLimiter):
  66         """
  67         Can be used to limit the choices for a :class:`ForeignKey` or :class:`ManyToManyField` to the :class:`ContentType`\ s for all non-abstract models which subclass the class passed in on instantiation.
  68
  69         :param cls: The class whose non-abstract subclasses will be valid choices.
  70         :param inclusive: Whether ``cls`` should also be considered a valid choice (if it is a non-abstract subclass of :class:`models.Model`)
  71
  72         """
  73         def __init__(self, cls, inclusive=False):
  74                 self.cls = cls
  75                 self.inclusive = inclusive
  76
  77         def q_object(self):
  78                 contenttype_pks = []
  79                 def handle_subclasses(cls):
  80                         for subclass in cls.__subclasses__():
  81                                 try:
  82                                         if issubclass(subclass, models.Model):
  83                                                 if not subclass._meta.abstract:
  84                                                         if not self.inclusive and subclass is self.cls:
  85                                                                 continue
  86                                                         contenttype = ContentType.objects.get_for_model(subclass)
  87                                                         contenttype_pks.append(contenttype.pk)
  88                                         handle_subclasses(subclass)
  89                                 except:
  90                                         pass
  91                 handle_subclasses(self.cls)
  92                 return models.Q(pk__in=contenttype_pks)
  93
  94
  95 ### Pagination
  96
  97
  98 def paginate(objects, per_page=None, page_number=1):
  99         """
 100         Given a list of objects, return a (``paginator``, ``page``, ``objects``) tuple.
 101
 102         :param objects: The list of objects to be paginated.
 103         :param per_page: The number of objects per page.
 104         :param page_number: The number of the current page.
 105         :returns tuple: (``paginator``, ``page``, ``objects``) where ``paginator`` is a :class:`django.core.paginator.Paginator` instance, ``page`` is the result of calling :meth:`Paginator.page` with ``page_number``, and objects is ``page.objects``. Any of the return values which can't be calculated will be returned as ``None``.
 106
 107         """
 108         try:
 109                 per_page = int(per_page)
 110         except (TypeError, ValueError):
 111                 # Then either it wasn't set or it was set to an invalid value
 112                 paginator = page = None
 113         else:
 114                 # There also shouldn't be pagination if the list is too short. Try count()
 115                 # first - good chance it's a queryset, where count is more efficient.
 116                 try:
 117                         if objects.count() <= per_page:
 118                                 paginator = page = None
 119                 except AttributeError:
 120                         if len(objects) <= per_page:
 121                                 paginator = page = None
 122
 123         try:
 124                 return paginator, page, objects
 125         except NameError:
 126                 pass
 127
 128         paginator = Paginator(objects, per_page)
 129         try:
 130                 page_number = int(page_number)
 131         except:
 132                 page_number = 1
 133
 134         try:
 135                 page = paginator.page(page_number)
 136         except EmptyPage:
 137                 page = None
 138         else:
 139                 objects = page.object_list
 140
 141         return paginator, page, objects