flask8:数据库对象序列化

1.在数据对象基类上增加__getitem__ 与 keys 方法，使对象可以通过字典形式序列化

class Base(db.Model):
    __abstract__ = True
    create_date = Column('create_date', DateTime)
    invalid_date =  Column('invalid_date', DateTime)
    stat = Column(String(10), default='normal')

    def __init__(self):
        self.create_date = datetime.now()
        self.stat = 'normal'

    def set_attrs(self, attrs_dict):
        for key, value in attrs_dict.items():
            if hasattr(self, key) and key != 'id':
                setattr(self, key, value)

    def delete(self):
        self.stat = 'invalid'
        self.invalid_date = datetime.now()

    # 返回对象对应属性的值
    def __getitem__(self, item):
        return getattr(self, item)

    # 定义返回字典中的键
    def keys(self):
        return self.fields

    def hide(self, *keys):
        for key in keys:
            self.fields.remove(key)
        return self

    def append(self, *keys):
        for key in keys:
            self.fields.append(key)
        return self

2.重写JSONEncoder函数，对不能序列化的对象指定***方式

class JSONEncoder(_JSONEncoder):
    def default(self, o):
        if hasattr(o, 'keys') and hasattr(o, '__getitem__'):
            return dict(o)
        if isinstance(o, date):
            return o.strftime('%Y-%m-%d')
        if isinstance(o, datetime):
            return o.strftime("%Y-%m-%d %H-%M-%S")
        raise ServerError()

3.重写Flask类，挂载新的JSONEncoder函数

class Flask(_Flask):
    json_encoder = JSONEncoder