Call the exists command to check if the redis key exists for the current
        field

def exists(self):
        """
        Call the exists command to check if the redis key exists for the current
        field
        """
        try:
            key = self.key
        except DoesNotExist:
            """
            If the object doesn't exists anymore, its PK is deleted, so the
            "self.key" call will raise a DoesNotExist exception. We catch it
            to return False, as the field doesn't exists too.
            """
            return False
        else:
            return self.connection.exists(key)