在管理中通过模型显示ManyToMany的过滤结果

Question

这是我的模型.py：

class Person(models.Model):

    surname = models.CharField(max_length=100, blank=True, null=True)
    forename = models.CharField(max_length=100, blank=True, null=True)

    def __str__(self):
        return '{}, {}'.format(self.surname, self.forename)

class PersonRole(models.Model):
    ROLE_CHOICES = [
        ("Principal investigator", "Principal investigator"),
        [etc...]
    ]
    title = models.CharField(choices=TITLE_CHOICES, max_length=9)
    project = models.ForeignKey('Project', on_delete=models.CASCADE)
    person = models.ForeignKey(Person, on_delete=models.CASCADE)
    person_role = models.CharField(choices=ROLE_CHOICES, max_length=30)

    def __str__(self):
        return '{}: {} as {}.'.format(self.project, self.person, self.person_role)

class Project(models.Model):

    title = models.CharField(max_length=200)
    person = models.ManyToManyField(Person, through=PersonRole)

    def __str__(self):
        return self.title

    def get_PI(self, obj):
        return [p.person for p in self.person.all()] #I'll then need to filter where person_role is 'Principal investigator', which should be the easy bit.

在我的管理后端中，我想在主表中显示该人（首席研究员）：

class ProjectAdmin(ImportExportModelAdmin):

    list_filter = [PersonFilter, FunderFilter]
    list_display = ("title", "get_PI")
    ordering = ('title',)

我想要的：在管理员的项目表中显示具有“首席研究员”角色的人员。

您可以看到我在我的

get_PI()

中创建了我的

models.py

并在我的

list_display

中创建了引用。我得到

Project.get_PI() missing 1 required positional argument: 'obj'

。我做错了什么？

Answer 1

删除

obj

参数：

class Project(models.Model):
    title = models.CharField(max_length=200)
    person = models.ManyToManyField(Person, through=PersonRole)

    def __str__(self):
        return self.title

    def get_PI(self):  # 🖘 no obj
        return [p.person for p in self.person.all()]

然而，这会引入 N+1 问题，因此您可能应该通过以下方式提高效率：

class ProjectAdmin(ImportExportModelAdmin):
    list_filter = [PersonFilter, FunderFilter]
    list_display = ('title', 'get_PI')
    ordering = ('title',)

    def get_queryset(self, request):
        return super().get_queryset(request).prefetch_related('person')

作为过滤，您可以使用：

class Project(models.Model):
    def get_PI(self):
        return [
            p
            for p in self.person.filter(
                personrole__title__contains='Principal investigator'
            )
        ]

然而，这将再次减慢查询速度，因为现在我们再次对每条记录执行一个查询。