Customizacion de Admin para exportar objetos

admin.py

from django.core import serializers

class ModelOneAdmin(admin.ModelAdmin):
    actions = ['exportar']

    def exportar(self, request, queryset):
        response = HttpResponse(content_type="text/javascript")
        response['Content-Disposition'] = 'attachment; filename=exportado.json'
        serializers.serialize("json", queryset, stream=response, ensure_ascii=False, indent=2)
        return response

    exportar.short_description = "Exportar objetos seleccionados"

admin.site.register(ModelOne, ModelOneAdmin)