Flask/SQLAlchemy:不兼容的集合类型：None不是listli

2024-05-13 12:02:01 发布

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我很困惑。怎么了？在

我有两个模型，一个多对一的关系。在

我创建了表单Boss_add，用于向数据库添加boss。 但是，什么都不管用！在

我的模型：

class User(UserMixin, db.Model):
  __tablename__ = 'users'

  id = db.Column(db.Integer, primary_key=True)
  username = db.Column(db.String(20), unique=True, nullable=False)
  boss_id = db.Column(db.Integer, db.ForeignKey('boss.id'))
  boss = db.relationship('Boss', back_populates='users')

class Boss(db.Model):
  __tablename__ = 'boss'

  id = db.Column(db.Integer, primary_key=True)
  short_name = db.Column(db.String(64))
  users = db.relationship('User', back_populates='boss')

我的表格：

^{pr2}$

我的观点：

@app.route('/boss_add/', methods=['GET', 'POST'])
@login_required
def boss_add():
  form = Boss_add()
  if request.method == 'POST' and form.validate():
    print("FIRST PRINT: ", type(form.users.data))   # DEBUG PRING 1
    print("SECOND PRINT: ", form.data)              # DEBUG PRING 2
    boss = Boss(short_name=form.short_name.data,
                users=form.users.data)
    db.session.add(boss)
    db.session.commit()
  return render_template('boss_edit.html', form=form)

我的模板：

<html><head><title>Boss add</title></head>
<body>
    <form action="" method="post" novalidate>
        {{ form.hidden_tag() }}
<p>
            {{ form.short_name.label }}<br>
            {{ form.short_name }}
        </p>
        <p>
            {{ form.users.label }}<br>
            {{ form.users }}
        </p>
        <p>{{ form.button() }}</p>
</form>
</body></html>

调试打印：

如果我在列表中选择用户

FIRST PRINT: <class 'list'>
SECOND PRINT: {'short_name': '1111', 'users': [<User 1>], 'button': True, 'csrf_token': 'IjYxNDFhYzYyOGNlMGMzYTliNGYxOTA2NDYxYmE1ZDZkZmVjMjVkNDUi.DqPGxg.63Z-bKn8dgRGLNLxgMLUEzKMa15'}

如果我没有在列表中选择用户

FIRST PRINT: <class 'list'>
SECOND PRINT: {'short_name': '1111', 'users': [], 'button': True, 'csrf_token': 'IjYxNDFhYzYyOGNlMGMzYTliNGYxOTA2NDYxYmE1ZDZkZmVjMjVkNDUi.DqPGxg.63Z-bKn8dgRGLNLxgMLUEzKMa15'}

类型错误：不兼容的集合类型：None不是list like

这怎么可能？类型：list，但错误：None。在

如果这很重要，我的libs：

alembic          1.0.0  
Click            7.0    
Flask            1.0.2  
Flask-Login      0.4.1  
Flask-Migrate    2.2.1  
Flask-SQLAlchemy 2.3.2  
Flask-WTF        0.14.2 
itsdangerous     0.24   
jdcal            1.4    
Jinja2           2.10   
Mako             1.0.7  
MarkupSafe       1.0    
pip              18.1   
pkg-resources    0.0.0  
python-dateutil  2.7.3  
python-editor    1.0.3  
setuptools       40.4.3 
six              1.11.0 
SQLAlchemy       1.2.12 
Werkzeug         0.14.1 
wheel            0.32.1 
WTForms          2.2.1

回溯：

Traceback (most recent call last):
  File "/lib/python3.7/site-packages/flask/app.py", line 2292, in wsgi_app
    response = self.full_dispatch_request()
  File "/lib/python3.7/site-packages/flask/app.py", line 1815, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/lib/python3.7/site-packages/flask/app.py", line 1718, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/lib/python3.7/site-packages/flask/_compat.py", line 35, in reraise
    raise value
  File "/lib/python3.7/site-packages/flask/app.py", line 1813, in full_dispatch_request
    rv = self.dispatch_request()
  File "/lib/python3.7/site-packages/flask/app.py", line 1799, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/lib/python3.7/site-packages/flask_login/utils.py", line 261, in decorated_view
    return func(*args, **kwargs)
  File "/src/app/routes.py", line 313, in client_add
    users=form.users.data)
  File "<string>", line 4, in __init__
  File "/lib/python3.7/site-packages/sqlalchemy/orm/state.py", line 424, in _initialize_instance
    manager.dispatch.init_failure(self, args, kwargs)
  File "/lib/python3.7/site-packages/sqlalchemy/util/langhelpers.py", line 66, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 249, in reraise
    raise value
  File "/lib/python3.7/site-packages/sqlalchemy/orm/state.py", line 421, in _initialize_instance
    return manager.original_init(*mixed[1:], **kwargs)
  File "/lib/python3.7/site-packages/sqlalchemy/ext/declarative/base.py", line 747, in _declarative_constructor
    setattr(self, k, kwargs[k])
  File "/lib/python3.7/site-packages/sqlalchemy/orm/attributes.py", line 229, in __set__
    instance_dict(instance), value, None)
  File "/lib/python3.7/site-packages/sqlalchemy/orm/attributes.py", line 1042, in set
    given, wanted))
TypeError: Incompatible collection type: None is not list-like

Tags： nameinpyformaddappdblib
1条回答
网友
1楼 · 发布于 2024-05-13 12:02:01

好吧，问题是您试图用None值填充users上的Boss模型

在您的view中尝试此操作：

boss = Boss(short_name=form.short_name.data)
if form.users.data:
    for each in form.users.data: boss.users.append(each)
db.session.add(boss)
db.session.commit()

它应该能很好地工作

有可能这个也能用

^{pr2}$

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