管理或视图中的自引用对称多对多 Django 模型

Question

如何在 M2M django 模型中获得对称自引用的另一面？

假设我们正在制作零件目录，我们有很多 Part，我们想要一个 Interchange 来显示哪些零件可以代替另一个：

class Part(models.Model):
    name = models.CharField(max_length=300)
    number = models.CharField(max_length=200, default 'because numberphiles like more ids')
    …
    interchanges = models.ManyToManyField("self",
                                          through='Interchange',
                                          symmetrical=False,
                                          # + sign per http://charlesleifer.com/blog/self-referencing-many-many-through/
                                          # I have tried without the plus t omaintain the references as well, but can't seem to understand the difference(s)
                                          related_name="interchanges_to+",
                                          # through_fields per docs
                                          through_fields=('reference', 'interchange')
                                          )

    # per this http://charlesleifer.com/blog/self-referencing-many-many-through/
    def add_interchange(self, part, symm=True):
        interchange = models.Interchange.objects.get_or_create(
            reference_part=self,
            interchange_part=part)
        if symm:
            # avoid recursion by passing `symm=False`
            part.add_interchange(self, False)
        return interchange

    def remove_interchange(self, part, symm=True):
        models.Interchange.objects.filter(
            reference_part=self,
            interchange_part=part).delete()
        if symm:
            # avoid recursion by passing `symm=False`
            part.remove_interchange(self, False)

    def get_interchanges(self):
        return ", ".join([str(p) for p in self.interchanges.filter(interchange_part__reference=self)])

    def get_references(self):
        return …?
        # This is where I don't know how to get the Parts that are referring to it as being an interchange

class Interchange(models.Model):
    reference = models.ForeignKey(Part, related_name="reference_part")
    interchange = models.ForeignKey(Part, related_name="interchange_part")
    # just to confirm we have a M2M table, we will add a foregin key to a User if this interchange has been personally verified
    confirmed_by = models.ForeignKey(User, null=True, blank=True)
    # … others if needed

    class Meta:
        # because self-referencing, in this case, is silly, we make sure each part references another part
        unique_together = ('reference', 'interchange')

在 Django 管理中，我有：

@admin.register(app.Part)
class PartAdmin(admin.ModelAdmin):
    list_display = ['name', 
                    'number', 
                     # ▼ I can see the Parts itself Interchanges to
                    'get_interchanges', 
                     # ▼ I can not see the Parts that reference itself as being an Interchange
                    'get_references']

管理员中的零件模型供参考...

这是我的资料：

这是我想要得到的：

作为确认，管理中的交换模型：

如何获得对称自引用 M2M django 模型的另一面？
如何 return Part 在交换 table 中但在参考（第一）列中

备注：

使用 Django 1.11
我知道根据 docs

False

This 不错的文章帮助我走得很远，但在管理员中，我似乎无法让 interchange_part 在管理员中显示其 reference_part页面（因此我什至没有尝试在具有 different/particular 功能的视图中查看是否可行）
在 docs 中，它指出 through_keys 的元组的第二部分称为 target 模型，但我找不到引用第一部分的内容
我确信有一种方法可以深入多个层次，即如果第一个部分交换为 2，并且 2 => 3，那么 1 应该列出 2 和 3（但这不是重点片刻)
请指正我的误解，谢谢:)

Answer 1

如果 manytomany 具有通过 table 和 related_name 参数并且不包含 +，那么您可以直接访问该集：

def get_references(self):
    return ", ".join([str(p) for p in self.interchanges_to.all()])

请注意，我不确定 performance/complexity

管理或视图中的自引用对称多对多 Django 模型

Self Referencing Symmetrical Many to Many Django Model in Admin or View

django

django-models

many-to-many

django-orm