Flask-restless - How to convert a DELETE request into an UPDATE

Question

What is the proper way to convert a DELETE request into an UPDATE?

I am doing something like that:

api_manager.create_api(News,
                       methods=['GET', 'POST', 'DELETE', 'PUT'],
                       preprocessors={'DELETE': [pre_delete_news]})

def pre_delete_news(instance_id=None, **kw):
    # Set the deleted flag
    db.engine.execute("SET delete = True FROM news WHERE id = %d" % instance_id)
    # Block the DELETE request by raising an exception
    raise ProcessingException(description='Delete successfull', code=418)

This is not very clean, because I raise an exception to force the blocking of the delete request.