Due to specific reasons, I’m required to convert a Django code to Flask. I’m a complete beginner in Flask, so here’s my Django code:

# serializers.py
from rest_framework import serializers
from .models import Element, Reaction

class ElementSerializer(serializers.ModelSerializer):
    class Meta:
        model = Element
        fields = '__all__'

class ReactionSerializer(serializers.ModelSerializer):
    class Meta:
        model = Reaction
        fields = '__all__'

# views
class ElementViewSet(viewsets.ModelViewSet):
    queryset = Element.objects.all()
    serializer_class = ElementSerializer

class ReactionViewSet(viewsets.ModelViewSet):
    queryset = Reaction.objects.all()
    serializer_class = ReactionSerializer
    
@csrf_exempt
@require_POST
def test_reaction_api(request):
    try:
        data = json.loads(request.body.decode('utf-8'))

        element1_symbol = data.get('element1')
        element2_symbol = data.get('element2')

        if not element1_symbol or not element2_symbol:
            return JsonResponse({"error": "Both element1 and element2 are required."}, status=400)

        try:
            element1 = Element.objects.get(symbol=element1_symbol)
            element2 = Element.objects.get(symbol=element2_symbol)
        except Element.DoesNotExist:
            return JsonResponse({"error": "One or both elements do not exist."}, status=404)

        reaction = Reaction.objects.filter(element1=element1, element2=element2).first()
        if not reaction:
            reaction = Reaction.objects.filter(element1=element2, element2=element1).first()

        element1_data = ElementSerializer(element1).data
        element2_data = ElementSerializer(element2).data
        product_data = ElementSerializer(reaction.product).data if reaction else "No reaction"

        response_data = {
            "product": product_data,
            "element1": element1_data,
            "element2": element2_data,
        }

        return JsonResponse(response_data)

    except json.JSONDecodeError:
        return JsonResponse({"error": "Invalid JSON data"}, status=400)

And here’s my Flask code:

class ElementResource(Resource):
    def get(self):
        elements = Element.query.all()
        return {'elements': [element.json() for element in elements]}

    def post(self):
        data = request.get_json()
        name = data.get('name')
        symbol = data.get('symbol')
        
        if not name or not symbol:
            return {"error": "Name and symbol are required."}, 400
        
        element = Element(name=name, symbol=symbol)
        db.session.add(element)
        db.session.commit()
        
        return element.json(), 201


class ReactionResource(Resource):
    def get(self):
        reactions = Reaction.query.all()
        return {'reactions': [reaction.json() for reaction in reactions]}

    def post(self):
        parser = reqparse.RequestParser()
        parser.add_argument('element1_name', type=str, required=True, help='Element 1 Name is required')
        parser.add_argument('element2_name', type=str, required=True, help='Element 2 Name is required')
        parser.add_argument('product_name', type=str, required=True, help='Product Name is required')
        args = parser.parse_args()

        element1 = Element.query.filter_by(name=args['element1_name']).first()
        element2 = Element.query.filter_by(name=args['element2_name']).first()
        if not element1 or not element2:
            return {"error": "One or both elements do not exist."}, 404

        reaction = Reaction(element1_name=args['element1_name'], element2_name=args['element2_name'], product_name=args['product_name'])
        db.session.add(reaction)
        db.session.commit()

        return {
            "reaction": reaction.json(),
        }, 201



api.add_resource(ElementResource, '/api/elements/', '/elements/<int:element_id>')
api.add_resource(ReactionResource, '/api/reactions/', '/reactions/<int:reaction_id>')

Error: [1] ERROR RuntimeError: NG0900: Error trying to diff ‘[object Object]’. Only arrays and iterables are allowed

Error: [1] ERROR RuntimeError: NG0900: Error trying to diff ‘[object Object]’. Only arrays and iterables are allowed