models/fields.py

   1 from django.db import models
   2 from django import forms
   3 from django.core.exceptions import FieldError, ValidationError
   4 from django.utils import simplejson as json
   5 from django.utils.text import capfirst
   6 from philo.signals import entity_class_prepared
   7 from philo.validators import TemplateValidator, json_validator
   8
   9
  10 __all__ = ('JSONAttribute', 'ForeignKeyAttribute', 'ManyToManyAttribute')
  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                 from philo.models.base import Entity
  28                 if issubclass(cls, Entity):
  29                         self.name = name
  30                         self.attname = name
  31                         if self.verbose_name is None and name:
  32                                 self.verbose_name = name.replace('_', ' ')
  33                         entity_class_prepared.connect(self.actually_contribute_to_class, sender=cls)
  34                 else:
  35                         raise FieldError('%s instances can only be declared on Entity subclasses.' % self.__class__.__name__)
  36
  37         def formfield(self, *args, **kwargs):
  38                 raise NotImplementedError('EntityProxyField subclasses must implement a formfield method.')
  39
  40         def value_from_object(self, obj):
  41                 return getattr(obj, self.attname)
  42
  43
  44 class AttributeFieldDescriptor(object):
  45         def __init__(self, field):
  46                 self.field = field
  47
  48         def __get__(self, instance, owner):
  49                 if instance:
  50                         if self.field.key in instance._added_attribute_registry:
  51                                 return instance._added_attribute_registry[self.field.key]
  52                         if self.field.key in instance._removed_attribute_registry:
  53                                 return None
  54                         try:
  55                                 return instance.attributes[self.field.key]
  56                         except KeyError:
  57                                 return None
  58                 else:
  59                         raise AttributeError('The \'%s\' attribute can only be accessed from %s instances.' % (self.field.name, owner.__name__))
  60
  61         def __set__(self, instance, value):
  62                 raise NotImplementedError('AttributeFieldDescriptor subclasses must implement a __set__ method.')
  63
  64         def __delete__(self, instance):
  65                 if self.field.key in instance._added_attribute_registry:
  66                         del instance._added_attribute_registry[self.field.key]
  67                 instance._removed_attribute_registry.append(self.field.key)
  68
  69
  70 class JSONAttributeDescriptor(AttributeFieldDescriptor):
  71         def __set__(self, instance, value):
  72                 if self.field.key in instance._removed_attribute_registry:
  73                         instance._removed_attribute_registry.remove(self.field.key)
  74                 instance._added_attribute_registry[self.field.key] = value
  75
  76
  77 class ForeignKeyAttributeDescriptor(AttributeFieldDescriptor):
  78         def __set__(self, instance, value):
  79                 if isinstance(value, (models.Model, type(None))):
  80                         if self.field.key in instance._removed_attribute_registry:
  81                                 instance._removed_attribute_registry.remove(self.field.key)
  82                         instance._added_attribute_registry[self.field.key] = value
  83                 else:
  84                         raise AttributeError('The \'%s\' attribute can only be set using existing Model objects.' % self.field.name)
  85
  86
  87 class ManyToManyAttributeDescriptor(AttributeFieldDescriptor):
  88         def __set__(self, instance, value):
  89                 if isinstance(value, models.QuerySet):
  90                         if self.field.key in instance._removed_attribute_registry:
  91                                 instance._removed_attribute_registry.remove(self.field.key)
  92                         instance._added_attribute_registry[self.field.key] = value
  93                 else:
  94                         raise AttributeError('The \'%s\' attribute can only be set to a QuerySet.' % self.field.name)
  95
  96
  97 class AttributeField(EntityProxyField):
  98         def contribute_to_class(self, cls, name):
  99                 super(AttributeField, self).contribute_to_class(cls, name)
 100                 if self.key is None:
 101                         self.key = name
 102
 103
 104 class JSONAttribute(AttributeField):
 105         descriptor_class = JSONAttributeDescriptor
 106
 107         def __init__(self, field_template=None, key=None, **kwargs):
 108                 super(AttributeField, self).__init__(**kwargs)
 109                 self.key = key
 110                 if field_template is None:
 111                         field_template = models.CharField(max_length=255)
 112                 self.field_template = field_template
 113
 114         def formfield(self, **kwargs):
 115                 defaults = {'required': False, 'label': capfirst(self.verbose_name), 'help_text': self.help_text}
 116                 defaults.update(kwargs)
 117                 return self.field_template.formfield(**defaults)
 118
 119         def value_from_object(self, obj):
 120                 return getattr(obj, self.attname).value
 121
 122
 123 class ForeignKeyAttribute(AttributeField):
 124         descriptor_class = ForeignKeyAttributeDescriptor
 125
 126         def __init__(self, model, limit_choices_to=None, key=None, **kwargs):
 127                 super(ForeignKeyAttribute, 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 formfield(self, form_class=forms.ModelChoiceField, **kwargs):
 135                 defaults = {'required': False, 'label': capfirst(self.verbose_name), 'help_text': self.help_text}
 136                 defaults.update(kwargs)
 137                 return form_class(self.model._default_manager.complex_filter(self.limit_choices_to), **defaults)
 138
 139         def value_from_object(self, obj):
 140                 relobj = super(ForeignKeyAttribute, self).value_from_object(obj).value
 141                 return getattr(relobj, 'pk', None)
 142
 143
 144 class ManyToManyAttribute(AttributeField):
 145         descriptor_class = ManyToManyAttributeDescriptor
 146         #FIXME: Add __init__ and formfield methods
 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 class JSONFormField(forms.Field):
 156         def clean(self, value):
 157                 try:
 158                         return json.loads(value)
 159                 except Exception, e:
 160                         raise ValidationError(u'JSON decode error: %s' % e)
 161
 162
 163 class JSONDescriptor(object):
 164         def __init__(self, field):
 165                 self.field = field
 166
 167         def __get__(self, instance, owner):
 168                 if instance is None:
 169                         raise AttributeError # ?
 170
 171                 if self.field.name not in instance.__dict__:
 172                         json_string = getattr(instance, self.field.attname)
 173                         instance.__dict__[self.field.name] = json.loads(json_string)
 174
 175                 return instance.__dict__[self.field.name]
 176
 177         def __set__(self, instance, value):
 178                 instance.__dict__[self.field.name] = value
 179                 setattr(instance, self.field.attname, json.dumps(value))
 180
 181         def __delete__(self, instance):
 182                 del(instance.__dict__[self.field.name])
 183                 setattr(instance, self.field.attname, json.dumps(None))
 184
 185
 186 class JSONField(models.TextField):
 187         def __init__(self, *args, **kwargs):
 188                 super(JSONField, self).__init__(*args, **kwargs)
 189                 self.validators.append(json_validator)
 190
 191         def get_attname(self):
 192                 return "%s_json" % self.name
 193
 194         def contribute_to_class(self, cls, name):
 195                 super(JSONField, self).contribute_to_class(cls, name)
 196                 setattr(cls, name, JSONDescriptor(self))
 197
 198         def formfield(self, *args, **kwargs):
 199                 kwargs["form_class"] = JSONFormField
 200                 return super(JSONField, self).formfield(*args, **kwargs)
 201
 202
 203 try:
 204         from south.modelsinspector import add_introspection_rules
 205 except ImportError:
 206         pass
 207 else:
 208         add_introspection_rules([], ["^philo\.models\.fields\.TemplateField"])
 209         add_introspection_rules([], ["^philo\.models\.fields\.JSONField"])