Product admin using specifications

gistfile1.py

class ProductAdmin(TranslationAdmin):
    list_filter = ['is_active', 'categories', 'specification', 'upgrades']
    filter_horizontal = ['upgrades', 'categories', 'matching_products']
    form = FormWithSpecification
    inlines = [
        PriceInline,
        SpecialPriceInline,
        EducationPriceInline,
        ProductImageInline,
    ]
    list_display = ('sku', '__unicode__', 'get_price')
    prepopulated_fields = {
        'slug': ('title',),
        }
    save_as = True  # TODO copy specification fields when saving as new

    def get_fieldsets(self, request, obj=None):
        fieldsets = super(ProductAdmin, self).get_fieldsets(request, obj=obj)

        if obj is not None and obj.specification:
            obj.specification.update_fields(obj)  # TODO redundant?
            # TODO groups!
            fieldsets.append((_('Specification'), {
                'fields': [field.formfield_name() for field in
                    obj.fields.select_related('field__group')],
                }))

        return fieldsets