'Handles checking if the data provided by the user is valid.
Mostly a hook, this uses class assigned to ``validation`` from
``Resource._meta``.
If validation fails, an error is raised with the error messages
serialized inside it.'

def is_valid(self, bundle):

    errors = self._meta.validation.is_valid(bundle, bundle.request)
    if errors:
        bundle.errors[self._meta.resource_name] = errors
        return False
    return True
