models/fields.py

   1 from django.db import models
   2 from django import forms
   3 from django.core.exceptions import FieldError
   4 from django.utils.text import capfirst
   5 from philo.models.base import Entity
   6 from philo.signals import entity_class_prepared
   7 from philo.validators import TemplateValidator
   8
   9
  10 __all__ = ('AttributeField', 'RelationshipField')
  11
  12
  13 class EntityProxyField(object):
  14         descriptor_class = None
  15
  16         def __init__(self, *args, **kwargs):
  17                 if self.descriptor_class is None:
  18                         raise NotImplementedError('EntityProxyField subclasses must specify a descriptor_class.')
  19                 self.verbose_name = kwargs.get('verbose_name', None)
  20                 self.help_text = kwargs.get('help_text', None)
  21
  22         def actually_contribute_to_class(self, sender, **kwargs):
  23                 sender._entity_meta.add_proxy_field(self)
  24                 setattr(sender, self.attname, self.descriptor_class(self))
  25
  26         def contribute_to_class(self, cls, name):
  27                 if issubclass(cls, Entity):
  28                         self.name = name
  29                         self.attname = name
  30                         if self.verbose_name is None and name:
  31                                 self.verbose_name = name.replace('_', ' ')
  32                         entity_class_prepared.connect(self.actually_contribute_to_class, sender=cls)
  33                 else:
  34                         raise FieldError('%s instances can only be declared on Entity subclasses.' % self.__class__.__name__)
  35
  36         def formfield(self, *args, **kwargs):
  37                 raise NotImplementedError('EntityProxyField subclasses must implement a formfield method.')
  38
  39         def value_from_object(self, obj):
  40                 return getattr(obj, self.attname)
  41
  42
  43 class AttributeFieldDescriptor(object):
  44         def __init__(self, field):
  45                 self.field = field
  46
  47         def __get__(self, instance, owner):
  48                 if instance:
  49                         if self.field.key in instance._added_attribute_registry:
  50                                 return instance._added_attribute_registry[self.field.key]
  51                         if self.field.key in instance._removed_attribute_registry:
  52                                 return None
  53                         try:
  54                                 return instance.attributes[self.field.key]
  55                         except KeyError:
  56                                 return None
  57                 else:
  58                         raise AttributeError('The \'%s\' attribute can only be accessed from %s instances.' % (self.field.name, owner.__name__))
  59
  60         def __set__(self, instance, value):
  61                 if self.field.key in instance._removed_attribute_registry:
  62                         instance._removed_attribute_registry.remove(self.field.key)
  63                 instance._added_attribute_registry[self.field.key] = value
  64
  65         def __delete__(self, instance):
  66                 if self.field.key in instance._added_attribute_registry:
  67                         del instance._added_attribute_registry[self.field.key]
  68                 instance._removed_attribute_registry.append(self.field.key)
  69
  70
  71 class AttributeField(EntityProxyField):
  72         descriptor_class = AttributeFieldDescriptor
  73
  74         def __init__(self, field_template=None, key=None, **kwargs):
  75                 super(AttributeField, self).__init__(**kwargs)
  76                 self.key = key
  77                 if field_template is None:
  78                         field_template = models.CharField(max_length=255)
  79                 self.field_template = field_template
  80
  81         def contribute_to_class(self, cls, name):
  82                 super(AttributeField, self).contribute_to_class(cls, name)
  83                 if self.key is None:
  84                         self.key = name
  85
  86         def formfield(self, **kwargs):
  87                 defaults = {'required': False, 'label': capfirst(self.verbose_name), 'help_text': self.help_text}
  88                 defaults.update(kwargs)
  89                 return self.field_template.formfield(**defaults)
  90
  91
  92 class RelationshipFieldDescriptor(object):
  93         def __init__(self, field):
  94                 self.field = field
  95
  96         def __get__(self, instance, owner):
  97                 if instance:
  98                         if self.field.key in instance._added_relationship_registry:
  99                                 return instance._added_relationship_registry[self.field.key]
 100                         if self.field.key in instance._removed_relationship_registry:
 101                                 return None
 102                         try:
 103                                 return instance.relationships[self.field.key]
 104                         except KeyError:
 105                                 return None
 106                 else:
 107                         raise AttributeError('The \'%s\' attribute can only be accessed from %s instances.' % (self.field.name, owner.__name__))
 108
 109         def __set__(self, instance, value):
 110                 if isinstance(value, (models.Model, type(None))):
 111                         if self.field.key in instance._removed_relationship_registry:
 112                                 instance._removed_relationship_registry.remove(self.field.key)
 113                         instance._added_relationship_registry[self.field.key] = value
 114                 else:
 115                         raise AttributeError('The \'%s\' attribute can only be set using existing Model objects.' % self.field.name)
 116
 117         def __delete__(self, instance):
 118                 if self.field.key in instance._added_relationship_registry:
 119                         del instance._added_relationship_registry[self.field.key]
 120                 instance._removed_relationship_registry.append(self.field.key)
 121
 122
 123 class RelationshipField(EntityProxyField):
 124         descriptor_class = RelationshipFieldDescriptor
 125
 126         def __init__(self, model, limit_choices_to=None, key=None, **kwargs):
 127                 super(RelationshipField, self).__init__(**kwargs)
 128                 self.key = key
 129                 self.model = model
 130                 if limit_choices_to is None:
 131                         limit_choices_to = {}
 132                 self.limit_choices_to = limit_choices_to
 133
 134         def contribute_to_class(self, cls, name):
 135                 super(RelationshipField, self).contribute_to_class(cls, name)
 136                 if self.key is None:
 137                         self.key = name
 138
 139         def formfield(self, form_class=forms.ModelChoiceField, **kwargs):
 140                 defaults = {'required': False, 'label': capfirst(self.verbose_name), 'help_text': self.help_text}
 141                 defaults.update(kwargs)
 142                 return form_class(self.model._default_manager.complex_filter(self.limit_choices_to), **defaults)
 143
 144         def value_from_object(self, obj):
 145                 relobj = super(RelationshipField, self).value_from_object(obj)
 146                 return getattr(relobj, 'pk', None)
 147
 148
 149 class TemplateField(models.TextField):
 150         def __init__(self, allow=None, disallow=None, secure=True, *args, **kwargs):
 151                 super(TemplateField, self).__init__(*args, **kwargs)
 152                 self.validators.append(TemplateValidator(allow, disallow, secure))
 153
 154
 155 try:
 156         from south.modelsinspector import add_introspection_rules
 157 except ImportError:
 158         pass
 159 else:
 160         add_introspection_rules([], ["^philo\.models\.fields\.TemplateField"])