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python - Flask/SQLAlchemy : Incompatible collection type: None is not list-like

转载 作者：太空宇宙 更新时间：2023-11-03 21:41:51 29 4
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我很困惑。怎么了？

我有两个模型，以及多对一的关系。

我创建了表单Boss_add用于将老板添加到数据库。但是，没有任何效果!

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:

from flask_wtf import FlaskForm
from wtforms import IntegerField, StringField, PasswordField, BooleanField, SubmitField, DateField
from wtforms.validators import ValidationError, DataRequired, Email, EqualTo
from wtforms.ext.sqlalchemy.fields import QuerySelectField, QuerySelectMultipleField
from app.models import User, Boss

class Boss_add(FlaskForm):
  short_name = StringField('Short name', validators=[DataRequired()])
  users = QuerySelectMultipleField('Users', query_factory=lambda: db.session.query(User), get_pk=lambda a: a.id, get_label=lambda a: a.username, allow_blank=True)
  button = SubmitField('Add')

我的看法:

@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:没有一​​个不是类似列表的

这怎么可能？类型:列表，但错误:无。

如果这很重要，我的库:

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

最佳答案

好吧，问题是您正在尝试使用 None 值填写 Boss 模型上的 users

在您的 View 中尝试一下:

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()

它应该工作得很好

这个也有可能有效

boss = Boss(short_name=form.short_name.data, users=form.users.data if form.users.data else [])

关于python - Flask/SQLAlchemy : Incompatible collection type: None is not list-like，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/52796520/

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