我无法将烧瓶_sqlalchemy的ORM转换为JSON并保存到列表

Question

我正在写一个烧瓶演示，我试着把ORM转换成json，然后返回到前面。

我为我的ORM创建了一个json函数，它们应该保存到我的列表中，但是它不起作用，例外说我的列表没有任何东西，这就是为什么？

这是我的ORM：

    class Metas(db.Model):
    __tablename__ = 'typecho_1metas'
    mid = db.Column(db.Integer, primary_key=True, autoincrement=True)
    name = db.Column(db.VARCHAR(200), nullable=False)
    slug = db.Column(db.VARCHAR(200), nullable=False)
    type = db.Column(db.VARCHAR(16), nullable=False)
    description = db.Column(db.Text, nullable=False)
    count = db.Column(db.Integer, nullable=False)
    order = db.Column(db.Integer, nullable=False)
    parent = db.Column(db.Integer, nullable=False)

    def to_json(self):
        return {
            'mid': self.mid,
            'name': self.name,
            'slug': self.slug,
            'type': self.type,
            'description': self.description,
            'count': self.count,
            'order': self.order,
            'parent': self.parent
        }
    def to_json_two(self):
        return {
            'name': self.name,
            'count': self.count
        }

这是我的密码：

@app.route('/index_data')
def index_data():
    engine = db.get_engine()
    engine.connect()

    data = Metas.query.filter(Metas.count > 0)
    alltag = [], tags = [], category = []
    for i in data:
        alltag.append(i.to_json_two())
        if i.type == 'tag':
            tags.append(i.to_json_two())
        else:
            category.append(i.to_json_two())


    data_list = {'alltag': alltag, 'tags': tags, 'category': category}

    return Response(json.dumps(data_list), mimetype='application/json')

这是例外：

Traceback (most recent call last):
  File "E:\Work\Py3\pydemo\myDemo\venv\lib\site-packages\flask\app.py", line 2548, in __call__
    return self.wsgi_app(environ, start_response)
  File "E:\Work\Py3\pydemo\myDemo\venv\lib\site-packages\flask\app.py", line 2528, in wsgi_app
    response = self.handle_exception(e)
  File "E:\Work\Py3\pydemo\myDemo\venv\lib\site-packages\flask\app.py", line 2525, in wsgi_app
    response = self.full_dispatch_request()
  File "E:\Work\Py3\pydemo\myDemo\venv\lib\site-packages\flask\app.py", line 1822, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "E:\Work\Py3\pydemo\myDemo\venv\lib\site-packages\flask\app.py", line 1820, in full_dispatch_request
    rv = self.dispatch_request()
  File "E:\Work\Py3\pydemo\myDemo\venv\lib\site-packages\flask\app.py", line 1796, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args)
  File "E:\Work\Py3\pydemo\myDemo\app.py", line 109, in index_data
    alltag = [], tags = [], category = []
ValueError: not enough values to unpack (expected 2, got 0)

Answer 1

我终于弄清楚了。

我不应该使用append()，这是没有意义的，否则，我改变了方式

我仍然保留着ORM的to_json()函数，所以我总是快速转换为json，我只需要在列表中列出-每一个。

@app.route('/index_data')
def index_data():
    engine = db.get_engine()
    engine.connect()

    # just get all tag
    allmeta = Metas.query.all()
    allmeta_json = [m.name for m in allmeta]

    # get category Metas and convert json
    category = Metas.query.filter(and_(Metas.count > 0), and_(Metas.type == 'category'))
    category_json = [m.to_json_two() for m in category]

    # get tag Metas and convert json
    tag = Metas.query.filter(and_(Metas.count > 0), and_(Metas.type == 'tag'))
    tag_json = [m.to_json_two() for m in tag]

    # add all
    data_list = {'alltag': allmeta_json, 'tags': tag_json, 'category': category_json}

    return Response(json.dumps(data_list), mimetype='application/json')