TypeError：<flask_script.commands.Command對象at>：__init __（）至少需要4個參數

Question

我正在通過https://realpython.com/blog/python/handling-email-confirmation-in-flask/#flask-basic-registration來構建電子郵件註冊系統。 （https://github.com/mjhea0/flask-basic-registration）

在models.py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我可以運行管理功能，看起來像：

@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() 

當我這樣做，我得到：

$ 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) 

我在做什麼錯？

Answer 1

在Python中有兩種類型的參數。

def function(arg1, arg2, arg3): 

和關鍵字參數是這樣定義的：

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

所有位置參數總是必需的，關鍵字參數是可選的（他們將採取在給予他們的價值是這樣定義的位置參數默認情況下如果你沒有明確地給它們定義）。您正嘗試將位置參數作爲關鍵字參數進行調用。您也無法提供所需的registered_on位置參數。如果您取出關鍵字create_admin並添加位置registered_on參數，使它看起來像這樣它應該運行：

@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() 

如果你想改變的定義，而不是叫你可以這樣做，而不是：

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組合，牢記我說的位置和關鍵字參數。