AttributeError：无法设置属性 - 我该如何解决？

Question

我正在使用 pytest 开发测试，但遇到 AttributeError: can't set attribute。

这是模型：

class User(UserMixin, db.Entity):
   _table_ = 'users'
   email = Required(str, unique=True)
   username = Required(str, unique=True)
   password_hash = Optional(str)
   pretax_income = Optional(Decimal, default=110000)
   tax_rate = Optional(Decimal, default=0.1)

   @property
   @db_session
   def monthly_income(self):
      return round(self.pretax_income/12, 2)

   @property
   @db_session
   def post_tax_income(self):
      return round(self.pretax_income - (self.pretax_income * self.tax_rate), 2)

  @property
  @db_session
  def post_tax_income_monthly(self):
      return round(self.post_tax_income / 12, 2)

这就是我做测试的地方，前两个工作正常。最后一个测试每月税后收入得到关于设置属性的错误。

class TestCalculator:

@db_session
def test_calc_monthly_income(self):
    user = User.get(email='test@test.com')
    user.pretax_income = 12000
    assert user.monthly_income == Decimal('1000')
    user.pretax_income = 48000
    assert user.monthly_income== Decimal('4000')

@db_session
def test_calc_post_tax_income(self):
    user = User.get(email='test@test.com')
    user.pretax_income = 120000
    user.tax_rate = 0.1
    assert user.post_tax_income == 108000
    user.pretax_income = 90000
    user.tax_rate = 0.2
    assert user.post_tax_income == 72000

@db_session
def test_calc_post_tax_income_monthly(self):
    user = User.get(email='test@test.com')
    user.post_tax_income = 36000
    assert user.post_tax_income_monthly == Decimal('3000')
    user.post_tax_income = 60000
    assert user.post_tax_income_monthly == Decimal('5000')

更新：我尝试以这种方式添加 setter。很明显，我做错了。

   @post_tax_income.setter
@db_session
def set_post_tax_income(self):
    self.post_tax_income = post_tax_income

Answer 1

@property
@db_session
def post_tax_income(self):
  return round(self.pretax_income - (self.pretax_income * self.tax_rate), 2)

这仅定义了一个 getter。它允许您获取值，但您不能这样做：

user.post_tax_income = 36000

这需要同时定义一个setter：

@post_tax_income.setter
def set_post_tax_income(self):
  ...