@classmethod
def get_model_class(cls, error=True):
    """
        Returns the data model class for which the master view exists.
        """
    if not hasattr(cls, 'model_class') and error:
        raise NotImplementedError('You must define the `model_class` for: {}'
            .format(cls))
    return getattr(cls, 'model_class', None)
