philo/models/fields/__init__.py

   1 from django import forms
   2 from django.core.exceptions import ValidationError
   3 from django.core.validators import validate_slug
   4 from django.db import models
   5 from django.utils import simplejson as json
   6 from django.utils.text import capfirst
   7 from django.utils.translation import ugettext_lazy as _
   8
   9 from philo.forms.fields import JSONFormField
  10 from philo.utils.registry import RegistryIterator
  11 from philo.validators import TemplateValidator, json_validator
  12 #from philo.models.fields.entities import *
  13
  14
  15 class TemplateField(models.TextField):
  16         """A :class:`TextField` which is validated with a :class:`.TemplateValidator`. ``allow``, ``disallow``, and ``secure`` will be passed into the validator's construction."""
  17         def __init__(self, allow=None, disallow=None, secure=True, *args, **kwargs):
  18                 super(TemplateField, self).__init__(*args, **kwargs)
  19                 self.validators.append(TemplateValidator(allow, disallow, secure))
  20
  21
  22 class JSONDescriptor(object):
  23         def __init__(self, field):
  24                 self.field = field
  25
  26         def __get__(self, instance, owner):
  27                 if instance is None:
  28                         raise AttributeError # ?
  29
  30                 if self.field.name not in instance.__dict__:
  31                         json_string = getattr(instance, self.field.attname)
  32                         instance.__dict__[self.field.name] = json.loads(json_string)
  33
  34                 return instance.__dict__[self.field.name]
  35
  36         def __set__(self, instance, value):
  37                 instance.__dict__[self.field.name] = value
  38                 setattr(instance, self.field.attname, json.dumps(value))
  39
  40         def __delete__(self, instance):
  41                 del(instance.__dict__[self.field.name])
  42                 setattr(instance, self.field.attname, json.dumps(None))
  43
  44
  45 class JSONField(models.TextField):
  46         """A :class:`TextField` which stores its value on the model instance as a python object and stores its value in the database as JSON. Validated with :func:`.json_validator`."""
  47         default_validators = [json_validator]
  48
  49         def get_attname(self):
  50                 return "%s_json" % self.name
  51
  52         def contribute_to_class(self, cls, name):
  53                 super(JSONField, self).contribute_to_class(cls, name)
  54                 setattr(cls, name, JSONDescriptor(self))
  55                 models.signals.pre_init.connect(self.fix_init_kwarg, sender=cls)
  56
  57         def fix_init_kwarg(self, sender, args, kwargs, **signal_kwargs):
  58                 # Anything passed in as self.name is assumed to come from a serializer and
  59                 # will be treated as a json string.
  60                 if self.name in kwargs:
  61                         value = kwargs.pop(self.name)
  62
  63                         # Hack to handle the xml serializer's handling of "null"
  64                         if value is None:
  65                                 value = 'null'
  66
  67                         kwargs[self.attname] = value
  68
  69         def formfield(self, *args, **kwargs):
  70                 kwargs["form_class"] = JSONFormField
  71                 return super(JSONField, self).formfield(*args, **kwargs)
  72
  73
  74 class SlugMultipleChoiceField(models.Field):
  75         """Stores a selection of multiple items with unique slugs in the form of a comma-separated list. Also knows how to correctly handle :class:`RegistryIterator`\ s passed in as choices."""
  76         __metaclass__ = models.SubfieldBase
  77         description = _("Comma-separated slug field")
  78
  79         def get_internal_type(self):
  80                 return "TextField"
  81
  82         def to_python(self, value):
  83                 if not value:
  84                         return []
  85
  86                 if isinstance(value, list):
  87                         return value
  88
  89                 return value.split(',')
  90
  91         def get_prep_value(self, value):
  92                 return ','.join(value)
  93
  94         def formfield(self, **kwargs):
  95                 # This is necessary because django hard-codes TypedChoiceField for things with choices.
  96                 defaults = {
  97                         'widget': forms.CheckboxSelectMultiple,
  98                         'choices': self.get_choices(include_blank=False),
  99                         'label': capfirst(self.verbose_name),
 100                         'required': not self.blank,
 101                         'help_text': self.help_text
 102                 }
 103                 if self.has_default():
 104                         if callable(self.default):
 105                                 defaults['initial'] = self.default
 106                                 defaults['show_hidden_initial'] = True
 107                         else:
 108                                 defaults['initial'] = self.get_default()
 109
 110                 for k in kwargs.keys():
 111                         if k not in ('coerce', 'empty_value', 'choices', 'required',
 112                                                  'widget', 'label', 'initial', 'help_text',
 113                                                  'error_messages', 'show_hidden_initial'):
 114                                 del kwargs[k]
 115
 116                 defaults.update(kwargs)
 117                 form_class = forms.TypedMultipleChoiceField
 118                 return form_class(**defaults)
 119
 120         def validate(self, value, model_instance):
 121                 invalid_values = []
 122                 for val in value:
 123                         try:
 124                                 validate_slug(val)
 125                         except ValidationError:
 126                                 invalid_values.append(val)
 127
 128                 if invalid_values:
 129                         # should really make a custom message.
 130                         raise ValidationError(self.error_messages['invalid_choice'] % invalid_values)
 131
 132         def _get_choices(self):
 133                 if isinstance(self._choices, RegistryIterator):
 134                         return self._choices.copy()
 135                 elif hasattr(self._choices, 'next'):
 136                         choices, self._choices = itertools.tee(self._choices)
 137                         return choices
 138                 else:
 139                         return self._choices
 140         choices = property(_get_choices)
 141
 142
 143 try:
 144         from south.modelsinspector import add_introspection_rules
 145 except ImportError:
 146         pass
 147 else:
 148         add_introspection_rules([], ["^philo\.models\.fields\.SlugMultipleChoiceField"])
 149         add_introspection_rules([], ["^philo\.models\.fields\.TemplateField"])
 150         add_introspection_rules([], ["^philo\.models\.fields\.JSONField"])