如果没有传递值，则如何将默认值传递给变量？

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如果没有传递值，则如何将默认值传递给变量？

在Pydantic中，如果在字段中传入None，我可以设置一个默认值吗？

我有以下代码，但我觉得这里的验证器只在模型初始化时起作用，而不是其他时候。

我的代码：

class User(BaseModel):
    name: Optional[str] = ''
    password: Optional[str] = ''
    email: EmailStr
    
    @validator('name')
    def set_name(cls, name):
        return name or 'foo'

遇到的问题：

user = User(name=None, password='some_password', email='example@example.com')
print("Name is ", user.name)
# > 'Name is foo'
user.name = None
print("Name is ", user.name)
# > 'Name is None'

期望的输出：

user = User(name='some_name', password='some_password', email='example@example.com')
user.name = None
print("Name is ", user.name)
# > 'Name is foo'

有什么想法可以实现期望的输出吗？我认为使用getter和setter可以解决这个问题。然而，我无法在Pydantic模型中使其工作：

尝试实现getter和setter：

class User(BaseModel):
    name: Optional[str] = ''
    password: Optional[str] = ''
    email: EmailStr
    
    def get_password(self):
        return self.password
    
    def set_password(self, password):
        self.password = hash_password(password)
    
    password = property(get_password, set_password)
    
user = User(name='some_name', password='some_password', email='example@example.com')
# > RecursionError: maximum recursion depth exceeded

我还尝试了使用property装饰器：

class User(BaseModel):
    name: Optional[str] = ''
    password: Optional[str] = ''
    email: EmailStr
    
    @property
    def password(self):
        return self._password
    
    @password.setter
    def password(self, password):
        pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
        self._password = pwd_context.hash(password)
        
user = User(name='some_name', email='example@example.com')
user.password = 'some_password'
# > ValueError: "User" object has no field "password"

我还尝试重写init方法：

class User(BaseModel):
    name: Optional[str] = ""
    password: Optional[str] = ""
    email: EmailStr
    
    def __init__(self, name, password, email):
        pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
        password = pwd_context.hash(password)
        super().__init__(name=name, password=password, email=email)
        
user = User(name="some_name", password="some_password", email='example@example.com')
print(user.password)
# > AYylwSnbQgCHrl4uue6kO7yiuT20lazSzK7x # 正常工作
user.password = "some_other_password"
print(user.password)
# > "some_other_password" # 不起作用
user.password = None
print(user.password)
# > None # 也不起作用

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