python 3.x - In django-rest-framework, serialize model from a different class -

i writing point-of-sale (pos) system in django. have basic functionality, , before go adding more complexity trying clean code.

as part of effort moving ajax calls part of api django-rest-framework.

in models have transaction represents items customer has purchased. each individual purchase in transaction lineitem. in transactionviewset api class have function named ring_plu. takes in upc , quantity, adds item lineitem upc, , want return new lineitem. code looks this.

transactionviewset     @detail_route(         methods=['post'],         renderer_classes=[renderers.statichtmlrenderer]     )     def ring_upc(self, request, *args, **kwargs):         upc = request.post['upc']         quantity = request.post['quantity']         if len(upc) != 12:             return response('invalid upc', status=status.http_400_bad_request)         grocery = get_object_or_404(grocery, upc=upc)         transaction = self.get_object()         line_item = transaction.create_line_item(grocery, quantity)         serializer = lineitemserializer(line_item, context={'request':request})         return response(serializer.data) 

i calling /api/transactions/10/ring_upc/ post body {'upc':'071990095314','quantity':1} , requesting application/json response. this.

urlcodequantityscaledescriptionpricestatustransactionitem

i have played around few different options serializers, cannot seem serializer work correctly.

here other parts of code may useful.

serializers.py

class lineitemserializer(serializers.hyperlinkedmodelserializer):     class meta:         model = lineitem 

models.py

class lineitem(models.model):     transaction = models.foreignkey(transaction)     code = models.charfield(max_length=30)     quantity = models.decimalfield(max_digits=15, decimal_places=0)     scale = models.decimalfield(max_digits=19, decimal_places=4, null=true)     description = models.charfield(max_length=100)     price = models.decimalfield(max_digits=17, decimal_places=2)     item = models.foreignkey('inventory.item')     status = models.charfield(max_length=8, default='active')      def __unicode__(self):         return str(self.scale) + ' x ' + self.description + ' ' +\             self.description      def total(self):         return self.price * self.quantity      def cancel(self):         self.status = 'inactive' 

the problem in renderers.statichtmlrenderer.

from documentation renderer is:

a simple renderer returns pre-rendered html. unlike other renderers, data passed response object should string representing content returned.

renderer expects plain text in response data. receives dict , transforms string iterating on it.

you can remove renderer_classes=[renderers.statichtmlrenderer] @detail_route arguments.