Move EncapsulatedObject class to common app

apps/common/classes.py

@@ -0,0 +1,133 @@
+from __future__ import absolute_import
+
+import logging
+import sys
+import types
+
+from django.contrib.contenttypes.models import ContentType
+from django.db.models.base import ModelBase
+from django.template.defaultfilters import capfirst
+from django.core.exceptions import ObjectDoesNotExist
+
+from common.models import AnonymousUserSingleton
+
+logger = logging.getLogger(__name__)
+
+_cache = {}
+
+
+def get_source_object(obj):
+    try:
+        return obj.source_object
+    except AttributeError:
+        return obj
+
+
+class EncapsulatedObject(object):
+    source_object_name = u'source_object'
+
+    @classmethod
+    def object_key(cls, app_label=None, model=None, pk=None):
+        if pk:
+            return '%s.%s.%s.%s' % (cls.__name__, app_label, model, pk)
+        else:
+            return '%s.%s.%s' % (cls.__name__, app_label, model)
+
+    @classmethod
+    def add_to_class(cls, name, value):
+        if hasattr(value, 'contribute_to_class'):
+            value.contribute_to_class(cls, name)
+        else:
+            setattr(cls, name, value)
+
+    @classmethod
+    def set_source_object_name(cls, new_name):
+        cls.source_object_name = new_name
+
+    #@classmethod
+    #def encapsulate_list(cls, source_object=None, app_label=None, model=None, pk=None):
+
+    @classmethod
+    def encapsulate(cls, source_object):
+        source_object = AnonymousUserSingleton.objects.passthru_check(source_object)
+        content_type = ContentType.objects.get_for_model(source_object)
+
+        if hasattr(source_object, 'pk'):
+            # Object
+            object_key = cls.object_key(content_type.app_label, content_type.model, source_object.pk)
+        else:
+            # Class
+            object_key = cls.object_key(content_type.app_label, content_type.model)
+
+        try:
+            return _cache[object_key]
+        except KeyError:
+            encapsulated_object = cls(source_object)
+            _cache[object_key] = encapsulated_object
+            return encapsulated_object
+
+    @classmethod
+    def get(cls, gid):
+        elements = gid.split('.')
+        if len(elements) == 3:
+            app_label, model, pk = elements[0], elements[1], elements[2]
+        elif len(elements) == 2:
+            app_label, model = elements[0], elements[1]
+            pk = None
+
+        object_key = cls.object_key(*elements)
+
+        try:
+            return _cache[object_key]
+        except KeyError:
+            try:
+                content_type = ContentType.objects.get(app_label=app_label, model=model)
+            except ContentType.DoesNotExist:
+                #cls.add_to_class('DoesNotExist', subclass_exception('DoesNotExist', (ObjectDoesNotExist,), cls.__name__))
+                #raise cls.DoesNotExist("%s matching query does not exist." % ContentType._meta.object_name)
+                raise ObjectDoesNotExist("%s matching query does not exist." % ContentType._meta.object_name)
+            else:
+                source_object_model_class = content_type.model_class()
+                if pk:
+                    try:
+                        source_object = content_type.get_object_for_this_type(pk=pk)
+                    except source_object_model_class.DoesNotExist:
+                        #cls.add_to_class('DoesNotExist', subclass_exception('DoesNotExist', (ObjectDoesNotExist,), cls.__name__))
+                        #raise cls.DoesNotExist("%s matching query does not exist." % source_object_model_class._meta.object_name)
+                        raise ObjectDoesNotExist("%s matching query does not exist." % source_object_model_class._meta.object_name)
+                else:
+                    source_object = source_object_model_class
+
+            return cls.encapsulate(source_object)
+
+    def __init__(self, source_object):
+        self.content_type = ContentType.objects.get_for_model(source_object)
+        self.ct_fullname = '%s.%s' % (self.content_type.app_label, self.content_type.model)
+
+        if isinstance(source_object, ModelBase):
+            # Class
+            self.gid = '%s.%s' % (self.content_type.app_label, self.content_type.model)
+        else:
+            # Object
+            self.gid = '%s.%s.%s' % (self.content_type.app_label, self.content_type.model, source_object.pk)
+
+        setattr(self, self.__class__.source_object_name, source_object)
+
+    def __unicode__(self):
+        if isinstance(self.source_object, ModelBase):
+            return capfirst(unicode(self.source_object._meta.verbose_name_plural))
+        elif self.ct_fullname == 'auth.user':
+            return u'%s %s' % (self.source_object._meta.verbose_name, self.source_object.get_full_name())
+        elif self.ct_fullname == 'common.anonymoususersingleton':
+            return unicode(self.source_object)
+        elif self.ct_fullname == 'acls.creatorsingleton':
+            return unicode(self.source_object)
+        else:
+            return u'%s %s' % (self.source_object._meta.verbose_name, self.source_object)
+
+    def __repr__(self):
+        return self.__unicode__()
+
+    @property
+    def source_object(self):
+        return getattr(self, self.__class__.source_object_name, None)