如何在两个 Django 类之间共享 Python 方法？

Question

我的 Django models.py 文件中有两个类：class ProfileManager(models.Manager):    def create_profile(self, user, member):        # Set default age to 100 years old when profile is created.        years_ago100 = datetime.datetime.now() - datetime.timedelta(days=101 * 365)        age = calculate_age(years_ago100)       # <- Used here        profile = self.create(user=user, person_dob=years_ago100, person_age=age)        returnclass Profile(models.Model):    person_dob = models.DateField()    person_age = models.IntegerField()    objects = ProfileManager()    def save(self, *args, **kwargs):      # Update to real age when user edits profile for the first time.      self.person_age = calculate_age(self.person_dob)    # <- Used here too      super(Profile, self).save(*args, **kwargs)每个类都使用这个calculate_age方法：def calculate_age(born):    today = datetime.date.today()    return (today.year - born.year - ((today.month, today.day) < (born.month, born.day)))如何使两个类都可以访问此方法？一种简单的方法是像这样使方法全局化，但这似乎是一种笨拙的方法：def calculate_age(born):  ...class ProfileManager(models.Manager):  ...class Profile(models.Model):  ...另外，如果我想在这个特定模型模块之外访问该方法，这将不起作用。使用 Django 时有标准方法可以做到这一点吗？

Answer 1

我不知道你为什么认为它很笨拙。当 PyCharm 检测到某个方法不访问类成员并因此可以转换为静态方法或函数时，这种情况经常发生，PyCharm 甚至使它变得很方便。

最重要的是，Python 导入非常方便。是的，您可以从模块外部访问模块函数，语法与访问类相同：通过点引用访问成员。

模块：

# myapp/utils.py

def calculate_age(born):

    today = datetime.date.today()

    return (today.year - born.year - ((today.month, today.day) < (born.month, born.day)))

#otherapp/models.py

from myapp import utils

class UserProfile(models.Model):

    def clean(self):

        if utils.calculate_age(self.birthday) < 13:

            raise ValidationError("no minors below 13 allowed")

Answer 2

您可以将函数calculate_age保存到另一个文件中，然后将其导入到models.py文件的顶部。这将允许访问内部的所有类/方法/函数。

Answer 3

可以尝试诸如多重继承之类的东西吗？不太确定这会比您所做的事情的全局功能更好

class Profile(models.Model):

    person_dob = models.DateField()

    person_age = models.IntegerField()

    objects = ProfileManager()

    def save(self, *args, **kwargs):

        # Update to real age when user edits profile for the first time.

        self.person_age = self.calculate_age(self.person_dob)    # <- Used here too

        super(Profile, self).save(*args, **kwargs)

    def calculate_age(born):

        today = datetime.date.today()

        return (today.year - born.year - ((today.month, today.day) < (born.month, born.day)))

class ProfileManager(models.Manager, Profile):

    def create_profile(self, user, member):

        # Set default age to 100 years old when profile is created.

        years_ago100 = datetime.datetime.now() - datetime.timedelta(days=101 * 365)

        age = self.calculate_age(years_ago100)       # <- Used here

        profile = self.create(user=user, person_dob=years_ago100, person_age=age)

        return

如果您不喜欢从 Profile 类继承整个 models.Model ，您可以创建一个共享类，它们都可以继承。

class Profile(models.Model, helpers):

    person_dob = models.DateField()

    person_age = models.IntegerField()

    objects = ProfileManager()

    def save(self, *args, **kwargs):

        # Update to real age when user edits profile for the first time.

        self.person_age = self.calculate_age(self.person_dob)    # <- Used here too

        super(Profile, self).save(*args, **kwargs)

class ProfileManager(models.Manager, helpers):

    def create_profile(self, user, member):

        # Set default age to 100 years old when profile is created.

        years_ago100 = datetime.datetime.now() - datetime.timedelta(days=101 * 365)

        age = self.calculate_age(years_ago100)       # <- Used here

        profile = self.create(user=user, person_dob=years_ago100, person_age=age)

        return

class helpers():

    def calculate_age(self, born):

        today = datetime.date.today()

        return (today.year - born.year - ((today.month, today.day) < (born.month, born.day)))

    def other_shared_method(self):

        pass