Django Many to Many Inline - how to show fields referenced by through model?

Question

I'm trying to customize and many to many inline in the django Admin, but I'm not able to display the fields of the underlying models.

Here's a simplified example. Maybe you can tell me how to reference them?

Here are my models:

class Clown(models.Model):
    name = models.CharField(max_length=255)
    def edit_link(self):
        return ...

class Circus(models.Model):
    clowns = models.ManyToManyField(Clown, blank=True, through='WorkedAt')
    name = models.CharField(max_length=255)

class WorkedAt(models.Model):
    clown = models.ForeignKey(Clown)
    circus = models.ForeignKey(Circus)

and my admin:

class ClownInline(admin.TabularInline):
    model = WorkedAt
    fields = ['clown__name','clown__edit_link']


class CircusAdmin(admin.ModelAdmin):
    inlines = [
        ClownInline,
    ]
    exclude = ('clowns',)

However I get this error:

Unknown field(s) (clown__name) specified for WorkedAt

(I'm on Django 1.6)

Update: Why won't this work either. (Added calculated field to through model.)

class Clown(models.Model):
    name = models.CharField(max_length=255)
    def edit_link(self):
        return ...

class Circus(models.Model):
    clowns = models.ManyToManyField(Clown, blank=True, through='WorkedAt')
    name = models.CharField(max_length=255)

class WorkedAt(models.Model):
    clown = models.ForeignKey(Clown)
    circus = models.ForeignKey(Circus)
    @property
    def edit_link(self):
        return self.clown.edit_link()

and my admin:

class ClownInline(admin.TabularInline):
    model = WorkedAt
    fields = ['edit_link']


class CircusAdmin(admin.ModelAdmin):
    inlines = [
        ClownInline,
    ]
    exclude = ('clowns',)

Answer 1

Try this. Hope it solves your problem

class ClownInline(admin.TabularInline):
    model = WorkedAt
    fields = ['clown_name', 'clown_edit_link']
    readonly_fields = ['clown_name', 'clown_edit_link']

    def clown_name(self, instance):
        return instance.clown.name
    clown_name.short_description = 'clow name'

    def clown_edit_link(self, instance):
        url = reverse("admin:%s_%s_change" % (instance.clown._meta.app_label, instance.clown._meta.module_name), args=(instance.clown.pk,))
        return '<a href="%s">%s</a>' % (url, instance.clown.name)
    clown_edit_link.allow_tags = True


class CircusAdmin(admin.ModelAdmin):
    inlines = [
        ClownInline,
    ]
    exclude = ('clowns',)

Answer 2

I don't know if anyone still needs this, because this question is 4 years old but this solved my problem for in Django 2.0.3:

# models.py
class Clown(models.Model):
    name = models.CharField(max_length=255)
    def edit_link(self):
        return ...


class Circus(models.Model):
    clowns = models.ManyToManyField(Clown, blank=True, through='WorkedAt')
    name = models.CharField(max_length=255)


class WorkedAt(models.Model):
    clown = models.ForeignKey(Clown)
    circus = models.ForeignKey(Circus)


# admin.py
class WorkedAtInline(admin.TabularInline):
    model = WorkedAt
    extra = 1


class WorkedAtAdmin(admin.ModelAdmin):
    inlines = (WorkedAtInline,)


admin.site.register(Clown, WorkedAtAdmin)

Hope this helps anyone that stumbles upon this problem and looks into this answer.