|
- """
- Convenience routines for creating non-trivial Field subclasses, as well as
- backwards compatibility utilities.
-
- Add SubfieldBase as the metaclass for your Field subclass, implement
- to_python() and the other necessary methods and everything will work
- seamlessly.
- """
-
- import warnings
-
- from django.utils.deprecation import RemovedInDjango110Warning
-
-
- class SubfieldBase(type):
- """
- A metaclass for custom Field subclasses. This ensures the model's attribute
- has the descriptor protocol attached to it.
- """
- def __new__(cls, name, bases, attrs):
- warnings.warn("SubfieldBase has been deprecated. Use Field.from_db_value instead.",
- RemovedInDjango110Warning, stacklevel=2)
-
- new_class = super(SubfieldBase, cls).__new__(cls, name, bases, attrs)
- new_class.contribute_to_class = make_contrib(
- new_class, attrs.get('contribute_to_class')
- )
- return new_class
-
-
- class Creator(object):
- """
- A placeholder class that provides a way to set the attribute on the model.
- """
- def __init__(self, field):
- self.field = field
-
- def __get__(self, obj, type=None):
- if obj is None:
- return self
- return obj.__dict__[self.field.name]
-
- def __set__(self, obj, value):
- obj.__dict__[self.field.name] = self.field.to_python(value)
-
-
- def make_contrib(superclass, func=None):
- """
- Returns a suitable contribute_to_class() method for the Field subclass.
-
- If 'func' is passed in, it is the existing contribute_to_class() method on
- the subclass and it is called before anything else. It is assumed in this
- case that the existing contribute_to_class() calls all the necessary
- superclass methods.
- """
- def contribute_to_class(self, cls, name, **kwargs):
- if func:
- func(self, cls, name, **kwargs)
- else:
- super(superclass, self).contribute_to_class(cls, name, **kwargs)
- setattr(cls, self.name, Creator(self))
-
- return contribute_to_class
|
