TypeError：<flask_script.commands.command object =“”at =“”>：__ init __（）至少需要4个参数

Question

我正在通过https://realpython.com/blog/python/handling-email-confirmation-in-flask/#flask-basic-registration建立电子邮件注册系统。 （https://github.com/mjhea0/flask-basic-registration）

在models.py中有：

class User(db.Model):

__tablename__ = "users"

id = db.Column(db.Integer, primary_key=True)
email = db.Column(db.String, unique=True, nullable=False)
password = db.Column(db.String, nullable=False)
registered_on = db.Column(db.DateTime, nullable=False)
admin = db.Column(db.Boolean, nullable=False, default=False)
confirmed = db.Column(db.Boolean, nullable=False, default=False)
confirmed_on = db.Column(db.DateTime, nullable=True)

def __init__(self, email, password, registered_on, admin=False, confirmed=False, confirmed_on=None):
    self.email = email
    self.password = bcrypt.generate_password_hash(password)
    self.registered_on = datetime.datetime.now()
    self.admin = admin
    self.confirmed = confirmed
    self.confirmed_on = confirmed_on
     .....

在manage.py中，我可以运行看起来像这样的管理功能：

@manager.command
def create_admin():
    """Creates the admin user."""
    db.session.add(User(
        email="ad@min.com",
        password="admin",
        admin=True,
        confirmed=True,
        confirmed_on=datetime.datetime.now())
    )
    db.session.commit()

当我这样做时：

$ python manage.py create_admin
Traceback (most recent call last):
  File "manage.py", line 78, in <module>
    manager.run()
  File "c:\envs\virtalenvs\flask_mini\lib\site-packages\flask_script\__init__.py", line 412, in run
    result = self.handle(sys.argv[0], sys.argv[1:])
  File "c:\envs\virtalenvs\flask_mini\lib\site-packages\flask_script\__init__.py", line 383, in handle
    res = handle(*args, **config)
  File "c:\envs\virtalenvs\flask_mini\lib\site-packages\flask_script\commands.py", line 216, in __call__
    return self.run(*args, **kwargs)
  File "manage.py", line 30, in create_admin
    confirmed_on=datetime.datetime.now())
TypeError: <flask_script.commands.Command object at 0x03530410>: __init__() takes at least 4 arguments (6 given)

我做错了什么？

Answer 1

在Python中有两种类型的参数。定位参数定义如下：

def function(arg1, arg2, arg3):

和关键字参数定义如下：

def function(arg1="arg1 value", arg2="arg2 value"):

所有位置参数始终是必需的，关键字参数是可选的（如果您没有明确地将它们赋予函数，它们将默认采用定义中给定的值）。您正在尝试将位置参数作为关键字参数调用。您也未能提供所需的registered_on位置参数。如果你在create_admin中取出关键字并添加位置registered_on参数，使它看起来像这样，它应该运行：

@manager.command
def create_admin():
    """Creates the admin user."""
    db.session.add(User(
        "ad@min.com",
        "admin",
        datetime.datetime.now() # this is the registered_on argument
        admin=True,
        confirmed=True,
        confirmed_on=datetime.datetime.now())
    )
    db.session.commit()

如果您想更改定义而不是通话，则可以改为：

class User(db.Model):

__tablename__ = "users"

id = db.Column(db.Integer, primary_key=True)
email = db.Column(db.String, unique=True, nullable=False)
password = db.Column(db.String, nullable=False)
registered_on = db.Column(db.DateTime, nullable=False)
admin = db.Column(db.Boolean, nullable=False, default=False)
confirmed = db.Column(db.Boolean, nullable=False, default=False)
confirmed_on = db.Column(db.DateTime, nullable=True)

def __init__(self, email="user@host", password="password", registered_on=datetime.datetime.now(), admin=False, confirmed=False, confirmed_on=None):
    self.email = email
    self.password = bcrypt.generate_password_hash(password)
    self.registered_on = registered_on
    self.admin = admin
    self.confirmed = confirmed
    self.confirmed_on = confirmed_on
     .....

或者你可以做一些上述的组合，记住我对位置和关键字参数的看法。