The ordering column is not hidden with custom formset.

[sakimyto]

The ordering column is not hidden with custom formset.

For example:

models.py

class Post(models.Model):
    id = models.AutoField(primary_key=True)
    title = models.CharField()


class Image(models.Model):
    id = models.AutoField(primary_key=True)
    image = models.ImageField(verbose_name="画像")
    post = models.ForeignKey(Post, on_delete=models.CASCADE)
    sort = models.PositiveSmallIntegerField()

admin.py

class ImageInlineFormSet(BaseInlineFormSet):
    def clean(self):
        super(ImageInlineFormSet, self).clean()
        if not self.forms:
            raise ValidationError("Please add at least one post image.")


class ImageInline(SortableInlineAdminMixin, admin.TabularInline):
    model = Image
    formset = ImageInlineFormSet


class PostAdmin(admin.ModelAdmin):
    model = Post
    inlines = (ImageInline,)

Here's the problem:
When I try to add an image in ProductAdmin, I have to set sort manually.
This is not a serious problem, but I think that there is a better way.

A solution is to add adminsortable2.admin.CustomInlineFormSetMixin to ImageInlineFormSet.

admin.py

class ImageInlineFormSet(CustomInlineFormSetMixin, BaseInlineFormSet):
...

But 'CustomInlineFormSetMixin' is not declared in __all__.
So this is not a recommended method.

I want to know the best way.