如何与“直通”模型的父模型创建" related_name“关系(关于related_name继承)

Question

我有4个模型，包括一个M2M“直通”模型，可以有一个索引：

class TargetShape(models.Model):
    pass
    
class Page(models.Model):
    target_shapes = models.ManyToManyField(TargetShape, through='PageElement', related_name='pages')
    
class PageElement(models.Model):
    target_shape = models.ForeignKey(TargetShape, related_name='page_elements')
    page = models.ForeignKey(Page, related_name='page_elements')
    index = models.PositiveIntegerField(verbose_name='Order')
    

class WorkingSession(models.Model):
    user = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='working_sessions')

我定义了另一个模型Resolution，它使我能够将它们全部链接在一起，以便创建以下related_name关系：

working_session.resolutions
user.resolutions
target_shape.resolutions
page.resolutions
page_element.resolutions

要让它正常工作，我必须声明：

class Resolution(models.Model):
    # relations that would be needed from a DRY perspective:
    page_element = models.ForeignKey(PageElement, related_name='resolutions')
    working_session = models.ForeignKey(WorkingSession, related_name='resolutions')
    
    # relations I want to exist to use user.resolutions, target_shape.resolutions, page.resolutions: 
    user = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='resolutions')
    target_shape = models.ForeignKey(TargetShape, related_name='resolutions')
    page = models.ForeignKey(Page, related_name='resolutions')

然而，这并不是很枯燥。从DRY的角度来看，我应该能够将Resolution声明为仅链接到PageElement和WorkingSession，并推导/继承与父模型的关系：

class Resolution(models.Model):
    page_element = models.ForeignKey(PageElement, related_name='resolutions')
    working_session = models.ForeignKey(WorkingSession, related_name='resolutions')

但在这种情况下，我如何创建以下关系：

user.resolutions
target_shape.resolutions
page.resolutions

不经过以下步骤：

user.working_sessions.resolutions
target_shape.page_elements.resolutions
page.page_elements.resolutions

Answer 1

我所能想到的就是：

• 要么像

那样声明所有字段

• 或在用户、TargetShape和页面中声明分别返回以下属性的属性：

Resolution.objects.filter(working_session__user=self) Resolution.objects.filter(page_element__target_shape=self) Resolution.objects.filter(page_element__page=self)

那当然可以，但那不是很优雅...也不是很像姜戈人

有没有人知道更像Django的方式来定义这种关系？

Answer 2

我发现了另一种方法:在用户、TargetShape和页面中声明一个返回查询集的属性：

class Resolution(models.Model):
    page_element = models.ForeignKey(PageElement, related_name='resolutions')
    working_session = models.ForeignKey(WorkingSession, related_name='resolutions')

class PageElement(models.Model):
    target_shape = models.ForeignKey(TargetShape, related_name='page_elements')
    page = models.ForeignKey(Page, related_name='page_elements')
    index = models.PositiveIntegerField(verbose_name='Order')
    

class WorkingSession(models.Model):
    user = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='working_sessions')



class TargetShape(models.Model):
    @property
    def resolutions(self):
        return Resolution.objects.filter(page_element__target_shape=self) 

    
class Page(models.Model):
    @property
    def resolutions(self):
        return Resolution.objects.filter(page_element__page=self)

    target_shapes = models.ManyToManyField(TargetShape, through='PageElement', related_name='pages')