models/base.py

   1 from django.db import models
   2 from django.contrib.contenttypes.models import ContentType
   3 from django.contrib.contenttypes import generic
   4 from django.utils import simplejson as json
   5 from django.core.exceptions import ObjectDoesNotExist
   6 from philo.utils import ContentTypeRegistryLimiter
   7 from UserDict import DictMixin
   8
   9
  10 class Attribute(models.Model):
  11         entity_content_type = models.ForeignKey(ContentType, verbose_name='Entity type')
  12         entity_object_id = models.PositiveIntegerField(verbose_name='Entity ID')
  13         entity = generic.GenericForeignKey('entity_content_type', 'entity_object_id')
  14         key = models.CharField(max_length=255)
  15         json_value = models.TextField(verbose_name='Value (JSON)', help_text='This value must be valid JSON.')
  16
  17         def get_value(self):
  18                 return json.loads(self.json_value)
  19
  20         def set_value(self, value):
  21                 self.json_value = json.dumps(value)
  22
  23         def delete_value(self):
  24                 self.json_value = json.dumps(None)
  25
  26         value = property(get_value, set_value, delete_value)
  27
  28         def __unicode__(self):
  29                 return u'"%s": %s' % (self.key, self.value)
  30
  31         class Meta:
  32                 app_label = 'philo'
  33
  34
  35 value_content_type_limiter = ContentTypeRegistryLimiter()
  36
  37
  38 def register_value_model(model):
  39         value_content_type_limiter.register_class(model)
  40
  41
  42 def unregister_value_model(model):
  43         value_content_type_limiter.unregister_class(model)
  44
  45
  46
  47 class Relationship(models.Model):
  48         entity_content_type = models.ForeignKey(ContentType, related_name='relationship_entity_set', verbose_name='Entity type')
  49         entity_object_id = models.PositiveIntegerField(verbose_name='Entity ID')
  50         entity = generic.GenericForeignKey('entity_content_type', 'entity_object_id')
  51         key = models.CharField(max_length=255)
  52         value_content_type = models.ForeignKey(ContentType, related_name='relationship_value_set', limit_choices_to=value_content_type_limiter, verbose_name='Value type')
  53         value_object_id = models.PositiveIntegerField(verbose_name='Value ID')
  54         value = generic.GenericForeignKey('value_content_type', 'value_object_id')
  55
  56         def __unicode__(self):
  57                 return u'"%s": %s' % (self.key, self.value)
  58
  59         class Meta:
  60                 app_label = 'philo'
  61
  62
  63 class QuerySetMapper(object, DictMixin):
  64         def __init__(self, queryset, passthrough=None):
  65                 self.queryset = queryset
  66                 self.passthrough = passthrough
  67         def __getitem__(self, key):
  68                 try:
  69                         return self.queryset.get(key__exact=key).value
  70                 except ObjectDoesNotExist:
  71                         if self.passthrough:
  72                                 return self.passthrough.__getitem__(key)
  73                         raise KeyError
  74         def keys(self):
  75                 keys = set(self.queryset.values_list('key', flat=True).distinct())
  76                 if self.passthrough:
  77                         keys += set(self.passthrough.keys())
  78                 return list(keys)
  79
  80
  81 class Entity(models.Model):
  82         attribute_set = generic.GenericRelation(Attribute, content_type_field='entity_content_type', object_id_field='entity_object_id')
  83         relationship_set = generic.GenericRelation(Relationship, content_type_field='entity_content_type', object_id_field='entity_object_id')
  84
  85         @property
  86         def attributes(self):
  87                 return QuerySetMapper(self.attribute_set)
  88
  89         @property
  90         def relationships(self):
  91                 return QuerySetMapper(self.relationship_set)
  92
  93         class Meta:
  94                 abstract = True
  95                 app_label = 'philo'
  96
  97
  98 class TreeManager(models.Manager):
  99         use_for_related_fields = True
 100
 101         def roots(self):
 102                 return self.filter(parent__isnull=True)
 103
 104         def get_with_path(self, path, root=None, absolute_result=True, pathsep='/'):
 105                 """
 106                 Returns the object with the path, or None if there is no object with that path,
 107                 unless absolute_result is set to False, in which case it returns a tuple containing
 108                 the deepest object found along the path, and the remainder of the path after that
 109                 object as a string (or None in the case that there is no remaining path).
 110                 """
 111                 slugs = path.split(pathsep)
 112                 obj = root
 113                 remaining_slugs = list(slugs)
 114                 remainder = None
 115                 for slug in slugs:
 116                         remaining_slugs.remove(slug)
 117                         if slug: # ignore blank slugs, handles for multiple consecutive pathseps
 118                                 try:
 119                                         obj = self.get(slug__exact=slug, parent__exact=obj)
 120                                 except self.model.DoesNotExist:
 121                                         if absolute_result:
 122                                                 obj = None
 123                                         remaining_slugs.insert(0, slug)
 124                                         remainder = pathsep.join(remaining_slugs)
 125                                         break
 126                 if obj:
 127                         if absolute_result:
 128                                 return obj
 129                         else:
 130                                 return (obj, remainder)
 131                 raise self.model.DoesNotExist('%s matching query does not exist.' % self.model._meta.object_name)
 132
 133
 134 class TreeModel(models.Model):
 135         objects = TreeManager()
 136         parent = models.ForeignKey('self', related_name='children', null=True, blank=True)
 137         slug = models.SlugField()
 138
 139         def get_path(self, pathsep='/', field='slug'):
 140                 path = getattr(self, field, '?')
 141                 parent = self.parent
 142                 while parent:
 143                         path = getattr(parent, field, '?') + pathsep + path
 144                         parent = parent.parent
 145                 return path
 146         path = property(get_path)
 147
 148         def __unicode__(self):
 149                 return self.path
 150
 151         class Meta:
 152                 unique_together = (('parent', 'slug'),)
 153                 abstract = True
 154                 app_label = 'philo'
 155
 156
 157 class TreeEntity(TreeModel, Entity):
 158         @property
 159         def attributes(self):
 160                 if self.parent:
 161                         return QuerySetMapper(self.attribute_set, passthrough=self.parent.attributes)
 162                 return super(TreeEntity, self).attributes
 163
 164         @property
 165         def relationships(self):
 166                 if self.parent:
 167                         return QuerySetMapper(self.relationship_set, passthrough=self.parent.relationships)
 168                 return super(TreeEntity, self).relationships
 169
 170         class Meta:
 171                 abstract = True
 172                 app_label = 'philo'