ES 添加索引 index 数据时，要过滤 filter 部分数据不被索引，该怎么定义数据模型呢？

翻了下光头哥的博客介绍：

The first thing that I need, is to somehow find a generic way to indicate which model and which field or fields in it are to be indexed. I'm going to say that any model that needs indexing needs to define a searchable class attribute that lists the fields that need to be included in the index. For the Post model, these are the changes:

app/models.py: Add a __searchable__ attribute to the Post model.

class Post(db.Model):
    __searchable__ = ['body']
    # ...

例如 Post 数据类里增加 status = private (or public) 这个 filter：

class Post(db.Model):
    __searchable__ = ['body']
    status = private (or public)
    # ...

然后往 Elasticsearch 增加索引数据时，只选择 status = public 类型的 post.body，该怎么定义这个数据模型呢？ （意思是不能把 private 的数据添加到在 ES 里去）