I am still using Django 1.1, so I am still using a NullableForeignKey to override the default ForeignKey model to get around the cascade on delete when I need to.
(at the end is my NullableForeignKey that I am using)
What I can't figure out is how to convince pyCharm that the methods on the NullableForeignKey objects are actually there. example:
something = models.CharField(max_length=20)
return self.something + ' special'
myFoo = NullableForeignKey(Foo)
myVar = myFoo.getSomethingSpecial()
^^^^^^How do I get pyCharm to understand that this is OK (and know that myFoo.badFuncName() is a problem?
Just like a ForeignKey, but when related objects are deleted this object is
*not* deleted. As the name implies, this field is always NULLable.
def __init__(self, *args, **kwargs):
kwargs['null'] = kwargs['blank'] = True
super(NullableForeignKey, self).__init__(*args, **kwargs)
# Monkey patches the related classes ``_collect_sub_objects`` method
# to NULL out values in this field that point to the object that's about
# to be deleted.
# NOTE: Override _collect_sub_objects rather than delete so a custom delete
# method can still be used.
def contribute_to_related_class(self, cls, related):
super(NullableForeignKey, self).contribute_to_related_class(cls, related)
# Alias so that the closure below has access to the outer "self"
this_field = self
# define a method name to map the original `_collect_sub_objects` method to
_original_csb_attr_name = '_original_collect_sub_objects'
def _new_collect_sub_objects(self, *args, **kwargs):
# NULL out anything related to this object.
qn = connection.ops.quote_name
for related in self._meta.get_all_related_objects():
if isinstance(related.field, this_field.__class__):
table = qn(related.model._meta.db_table)
column = qn(related.field.column)
sql = "UPDATE %s SET %s = NULL WHERE %s = %%s;" % (table, column, column)
# Now proceed with collecting sub objects that are still tied via FK
getattr(self, _original_csb_attr_name)(*args, **kwargs)
# monkey patch the related classes _collect_sub_objects method.
# store the original method in an attr named `_original_csb_attr_name`
if not hasattr(cls, _original_csb_attr_name):
setattr(cls, _original_csb_attr_name, cls._collect_sub_objects)
setattr(cls, '_collect_sub_objects', _new_collect_sub_objects)