Reopened treechanges. Moved validation language to validators.py. Abstracted NodeForm...

[philo.git] / validators.py

diff --git a/validators.py b/validators.py
new file mode 100644 (file)
index 0000000..bc41d02
--- /dev/null
+++ b/validators.py
@@ -0,0 +1,77 @@
+from django.core.exceptions import ValidationError
+from django.utils.translation import ugettext_lazy as _
+
+
+class TreeParentValidator(object):
+       """
+       constructor takes instance and parent_attr, where instance is the model
+       being validated and parent_attr is where to look on that parent for the
+       comparison.
+       """
+       #message = _("A tree element can't be its own parent.")
+       code = 'invalid'
+       
+       def __init__(self, instance, parent_attr=None, message=None, code=None):
+               self.instance = instance
+               self.parent_attr = parent_attr
+               self.static_message = message
+               if code is not None:
+                       self.code = code
+       
+       def __call__(self, value):
+               """
+               Validates that the self.instance is not found in the parent tree of
+               the node given as value.
+               """
+               parent = value
+               
+               while parent:
+                       comparison=self.get_comparison(parent)
+                       if comparison == self.instance:
+                               # using (self.message, code=self.code) results in the admin interface
+                               # screwing with the error message and making it be 'Enter a valid value'
+                               raise ValidationError(self.message)
+                       parent=parent.parent
+       
+       def get_comparison(self, parent):
+               if self.parent_attr and hasattr(parent, self.parent_attr):
+                       return getattr(parent, self.parent_attr)
+               
+               return parent
+       
+       def get_message(self):
+               return self.static_message or _(u"A %s can't be its own parent." % self.instance.__class__.__name__)
+       message = property(get_message)
+       
+class TreePositionValidator(object):
+       code = 'invalid'
+       
+       def __init__(self, parent, slug, obj_class, message=None, code=None):
+               self.parent = parent
+               self.slug = slug
+               self.obj_class = obj_class
+               self.static_message = message
+                       
+               if code is not None:
+                       self.code = code
+       
+       def __call__(self, value):
+               """
+               Validates that there is no obj of obj_class with the same position
+               as the compared obj (value) but a different id.
+               """
+               if not isinstance(value, self.obj_class):
+                       raise ValidationError(_(u"The value must be an instance of %s." % self.obj_class.__name__))
+               
+               try:
+                       obj = self.obj_class.objects.get(slug=self.slug, parent=self.parent)
+                       
+                       if obj.id != value.id:
+                               raise ValidationError(self.message)
+                               
+               except self.obj_class.DoesNotExist:
+                       pass
+       
+       def get_message(self):
+               return self.static_message or _(u"A %s with that path (parent and slug) already exists." % self.obj_class.__name__)
+       message = property(get_message)