def get_perm_key(action, class_name, field_name):
    """
    Generate django permission code name.

    :Example:

        >> perm = get_perm_key('change', 'baseobject', 'remarks')
        change_baseobject_remarks_field

    :param action: Permission action (change/view)
    :type action: str
    :param class_name: Django model class name
    :type class_name: str
    :param field_name: Django model field name
    :type field_name: str

    :return: django permission code name
    :rtype: str
    """
    return '{}_{}_{}_field'.format(action, class_name, field_name)