validators.py

   1 from django.core.exceptions import ValidationError
   2 from django.utils.translation import ugettext_lazy as _
   3
   4
   5 class TreeParentValidator(object):
   6         """
   7         constructor takes instance and parent_attr, where instance is the model
   8         being validated and parent_attr is where to look on that parent for the
   9         comparison.
  10         """
  11         #message = _("A tree element can't be its own parent.")
  12         code = 'invalid'
  13
  14         def __init__(self, instance, parent_attr=None, message=None, code=None):
  15                 self.instance = instance
  16                 self.parent_attr = parent_attr
  17                 self.static_message = message
  18                 if code is not None:
  19                         self.code = code
  20
  21         def __call__(self, value):
  22                 """
  23                 Validates that the self.instance is not found in the parent tree of
  24                 the node given as value.
  25                 """
  26                 parent = value
  27
  28                 while parent:
  29                         comparison=self.get_comparison(parent)
  30                         if comparison == self.instance:
  31                                 # using (self.message, code=self.code) results in the admin interface
  32                                 # screwing with the error message and making it be 'Enter a valid value'
  33                                 raise ValidationError(self.message)
  34                         parent=parent.parent
  35
  36         def get_comparison(self, parent):
  37                 if self.parent_attr and hasattr(parent, self.parent_attr):
  38                         return getattr(parent, self.parent_attr)
  39
  40                 return parent
  41
  42         def get_message(self):
  43                 return self.static_message or _(u"A %s can't be its own parent." % self.instance.__class__.__name__)
  44         message = property(get_message)
  45
  46 class TreePositionValidator(object):
  47         code = 'invalid'
  48
  49         def __init__(self, parent, slug, obj_class, message=None, code=None):
  50                 self.parent = parent
  51                 self.slug = slug
  52                 self.obj_class = obj_class
  53                 self.static_message = message
  54
  55                 if code is not None:
  56                         self.code = code
  57
  58         def __call__(self, value):
  59                 """
  60                 Validates that there is no obj of obj_class with the same position
  61                 as the compared obj (value) but a different id.
  62                 """
  63                 if not isinstance(value, self.obj_class):
  64                         raise ValidationError(_(u"The value must be an instance of %s." % self.obj_class.__name__))
  65
  66                 try:
  67                         obj = self.obj_class.objects.get(slug=self.slug, parent=self.parent)
  68
  69                         if obj.id != value.id:
  70                                 raise ValidationError(self.message)
  71
  72                 except self.obj_class.DoesNotExist:
  73                         pass
  74
  75         def get_message(self):
  76                 return self.static_message or _(u"A %s with that path (parent and slug) already exists." % self.obj_class.__name__)
  77         message = property(get_message)