Adust the as_table tag to render a pick link if appropriate
The templates are adjusted to pass on a 'reference' value, which
is the url_name of the view from which the entity should be picked.
The as_table (and related) function(s) construct and then pass on
this argument and enable takes_contex so that we have access to the
context of the enclosing template.
We only extract ReferenceProperties that end with '_link_id' since
that is how all RP's are currently named. It is not possible to
create a field with the same name as the RP, as GAE will try to
interpret it's contents as the key of an entity before even calling
any function we can override.
Patch by: Sverre Rabbelier
"""
Convenience routines for creating non-trivial Field subclasses.
Add SubfieldBase as the __metaclass__ for your Field subclass, implement
to_python() and the other necessary methods and everything will work seamlessly.
"""
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, base, name, attrs):
new_class = super(SubfieldBase, cls).__new__(cls, base, name, attrs)
new_class.contribute_to_class = make_contrib(
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:
raise AttributeError('Can only be accessed via an instance.')
return obj.__dict__[self.field.name]
def __set__(self, obj, value):
obj.__dict__[self.field.name] = self.field.to_python(value)
def make_contrib(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):
if func:
func(self, cls, name)
else:
super(self.__class__, self).contribute_to_class(cls, name)
setattr(cls, self.name, Creator(self))
return contribute_to_class