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Best architecture for dynamically validating and saving field

I am looking for the good architecture for my problem. I am using django rest framework for building an API. I receive a list of dict which contains an id and a list of values. The list of values need to be validated according to the id.
Example of my code:
class AttributesSerializer(serializers.Serializer):
id = serializers.PrimaryKeyRelatedField(queryset=Attribute.objects.all(), source="attribute", required=True)
values = serializers.ListField()
def validate(self, validated_data):
attribute = validated_data["attribute"]
values = validated_data["values"]
# This function returns the corresponding field according to attribute
values_child_field = get_values_field(attribute)
self.fields["values"].child = values_child_fields
new_values = self.fields["values"].run_child_validation(values)
set_value(validated_data, "values", new_values)
return validated_data
class BaseObjectApiInputSerializer(serializers.Serializer):
category_id = serializers.PrimaryKeyRelatedField(
queryset=Category.objects.all()
)
attributes = AttributesSerializer(many=True)
I want to parse json like this:
{
"categorty_id": 42, # Category pk of the baseobject. which defines some constraints about attributes available
"attributes": [
{"id": 124, "values": ["value"]},
{"id": 321, "values": [42]},
{
"id": 18,
"values": [
{
"location": {"type": "Point", "geometry": {...}},
"address": "an address",
}
],
},
]
}
Currently, this code does not work. DRF seems to try to revalidate all values entries for each iteration with each child field. I do not understand why... I guess I could make it work without using this fields["values"] for making the validation and just retrieve the field and use it directly, but i need this field for making the save later.
Do you think my architecture is ok? What is the good way for parsing this type of data with DRF?
EDIT:
Structure of models are complex but a version simplified following:
class Attribute(models.Model):
class DataType(models.TextChoices):
TEXT = "TEXT", _("datatype_text")
INTEGER = "INTEGER", _("datatype_integer")
DATETIME = "DATETIME", _("datatype_datetime")
BOOL = "BOOL", _("datatype_bool")
# Some examples, but there are about 30 items with
# type very complicated like RecurrenceRule (RFC2445)
# or GeoJSON type
label = models.CharField()
category = models.ForeignKey(Category)
attribute_type = models.CharField(choices=DataType.choices)
class AttributeValue(models.Model):
attribute = models.ForeignKey(Attribute)
# a model which represents an object with list of attributes
baseobject = models.ForeignKey(BaseObject)
value = models.TextField()
AttributeValue is like a through table for manytomany relation between BaseObject model and Attribute model.
My JSON represents the list of attribute/values attached to a baseobject.
In fact I don't understand why DRf doesn't allow delegating registration in the child serializers of the parent serializer. This would allow much greater flexibility in code architecture and separation of responsibilities.
EDIT 2 :
My urls.py
router = routers.DefaultRouter()
router.register("baseobjects", BaseObjectViewSet, basename="baseobjects")
I am using the default router and url for DRF viewset.
The view looks like:
class BaseObjectViewSet(viewsets.ModelViewSet):
permission_classes = [IsAuthenticated]
authentication_classes = [TokenAuthentication]
def create(self, request, *args, **kwargs):
serializer = BaseObjectApiInputSerializer(
data=request.data
)
if not serializer.is_valid():
return Response(serializer.errors, status=HTTP_400_BAD_REQUEST)
baseobject: BaseObject = serializer.save()
return Response(
{"results": [{"id": baseobject.pk}]}, status=HTTP_200_OK
)

I think you should use ListField with JSONField as child argument for values field.
validators = {
TinyurlShortener.DataType.TEXT: serializers.CharField(),
TinyurlShortener.DataType.INTEGER: serializers.IntegerField(),
TinyurlShortener.DataType.DATETIME: serializers.DateTimeField(),
TinyurlShortener.DataType.BOOL: serializers.BooleanField(),
}
class AttributesSerializer(serializers.Serializer):
id = serializers.PrimaryKeyRelatedField(queryset=Attribute.objects.all(), source="attribute", required=True)
values = serializers.ListField(
child=serializers.JSONField()
)
def validate(self, attrs):
attribute = attrs.get('id')
field = validators[attribute.attribute_type]
for v in attrs['values']:
field.run_validation(json.loads(v.replace("'", '"')))
return super().validate(attrs)
class BaseObjectApiInputSerializer(serializers.Serializer):
category_id = serializers.PrimaryKeyRelatedField(
queryset=Category.objects.all()
)
attributes = AttributesSerializer(many=True)

Filter Embedded Document List in GraphQL

I'm building a GraphQL application in Python/Graphene using a MongoDB backend (through MongoEngine). Everything has been working well, but noticed that there's not a lot documentation for handling nested lists of embedded documents. I thought one power of GraphQL was the ability to project only the properties you want, but it doesn't appear to be the case fully.
Looking at this collection as an example:
[
{
"name": "John Doe",
"age": 37,
"preferences": [
{
"key": "colour",
"value": "Green"
},
{
"key": "smell",
"value": "onions cooking in butter"
},
...
]
},
...
]
If I want to find a particular object through GraphQL, I would look up through a query like
{
person(name: "John Doe"){edges{node{
name age preferences{edges{node{
key value
}}}
}}}
}
But this could bring back hundreds of nested documents. What I would like to do instead is to identify the requested nested documents as part of the projection request.
{
person(name: "John Doe"){edges{node{
name age preferences(key: "colour"){edges{node{
key value
}}}
}}}
}
My understanding reading the GraphQL spec is these sub-queries are not possible, but wanted to confirm with experts first. And if it is possible, how would I implement it to support these types of requests?
Update Maybe a schema example will provide some more insightful responses.
class PreferenceModel(mongoengine.EmbeddedDocument):
key = mongoengine.fields.StringField()
value = mongoengine.fields.StringField()
class Preference(graphene_mongo.MongoengineObjectType):
class Meta:
interfaces = (graphene.relay.Node, )
model = PreferenceModel
class PersonModel(mongoengine.Document):
meta = {'collection': 'persons'}
name = mongoengine.fields.StringField()
age = mongoengine.fields.IntField()
preferences = mongoengine.fields.EmbeddedDocumentListField(PreferenceModel)
class Person(graphene_mongo.MongoengineObjectType):
class Meta:
interfaces = (graphene.relay.Node, )
model = PersonModel
class Query(graphene.ObjectType):
person = graphene_mongo.MongoengineConnectionField(Person)
schema = graphene.Schema(query=Query, types=[Person])
app = starlette.graphql.GraphQLApp(schema=schema)
Using this above structure, what changes would be necessary to allow for queries/filters on nested objects?

I had a similiar issue but working graphene-django. I solved it using custom resolvers on the DjangoObjectType, like this:
import graphene
from graphene_django import DjangoObjectType
from .models import Question, Choice, SubChoice
class SubChoiceType(DjangoObjectType):
class Meta:
model = SubChoice
fields = "__all__"
class ChoiceType(DjangoObjectType):
sub_choices = graphene.List(SubChoiceType, search_sub_choices=graphene.String())
class Meta:
model = Choice
fields = ("id", "choice_text", "question")
def resolve_sub_choices(self, info, search_sub_choices=None):
if search_sub_choices:
return self.subchoice_set.filter(sub_choice_text__icontains=search_sub_choices)
return self.subchoice_set.all()
class QuestionType(DjangoObjectType):
choices = graphene.List(ChoiceType, search_choices=graphene.String())
class Meta:
model = Question
fields = ("id", "question_text")
def resolve_choices(self, info, search_choices=None):
if search_choices:
return self.choice_set.filter(choice_text__icontains=search_choices)
return self.choice_set.all()
class Query(graphene.ObjectType):
all_questions = graphene.List(QuestionType, search_text=graphene.String())
all_choices = graphene.List(ChoiceType, search_text=graphene.String())
all_sub_choices = graphene.List(SubChoiceType)
def resolve_all_questions(self, info, search_text=None):
qs = Question.objects.all()
if search_text:
qs = qs.filter(question_text__icontains=search_text)
return qs
def resolve_all_choices(self, info, search_text=None):
qs = Choice.objects.all()
if search_text:
qs = qs.filter(choice_text__icontains=search_text)
return qs
def resolve_all_sub_choices(self, info):
qs = SubChoice.objects.all()
return qs
schema = graphene.Schema(query=Query)
you can find the example here: https://github.com/allangz/graphene_subfilters/blob/main/mock_site/polls/schema.py
It may work for you

Retrieve the object ID in GraphQL

I'd like to know whether it is possible to get the "original id" of an object as the result of the query. Whenever I make a request to the server, it returns the node "global identifier", something like U29saWNpdGFjYW9UeXBlOjEzNTkxOA== .
The query is similar to this one:
{
allPatients(active: true) {
edges {
cursor
node {
id
state
name
}
}
}
and the return is:
{
"data": {
"edges": [
{
"cursor": "YXJyYXljb25uZWN0aW9uOjA=",
"node": {
"id": "U29saWNpdGFjYW9UeXBlOjEzNTkxOA==",
"state": "ARI",
"name": "Brad"
}
}
]
}
}
How can I get the "original" id of the object at the database level (e.g. '112') instead of that node unique identifier?
ps.: I am using graphene-python and Relay on the server side.

Overriding default to_global_id method in Node object worked out for me:
class CustomNode(graphene.Node):
class Meta:
name = 'Node'
#staticmethod
def to_global_id(type, id):
return id
class ExampleType(DjangoObjectType):
class Meta:
model = Example
interfaces = (CustomNode,)

First option, remove relay.Node as interface of your objectNode declaration.
Second option, use custom resolve_id fonction to return id original value.
Example
class objectNode(djangoObjectType):
.... Meta ....
id = graphene.Int(source="id")
def resolve_id("commons args ...."):
return self.id
Hope it helps

To expand on the top answer and for those using SQLAlchemy Object Types, this worked for me:
class CustomNode(graphene.Node):
class Meta:
name = 'myNode'
#staticmethod
def to_global_id(type, id):
return id
class ExampleType(SQLAlchemyObjectType):
class Meta:
model = Example
interfaces = (CustomNode, )
If you have other ObjectTypes using relay.Node as the interface, you will need to use a unique name under your CustomNode. Otherwise you will get and assertion error.

With this you can retrive the real id in database:
def get_real_id(node_id: str):
_, product_id_real = relay.Node.from_global_id(global_id=node_id)
return product_id_real

Django Rest Framework receive primary key value in POST and return model object as nested serializer

I'm not completely sure that the title of my question is as specific as I wanted it to be, but this is the case:
I have a HyperlinkedModelSerializer that looks like this:
class ParentArrivalSerializer(serializers.HyperlinkedModelSerializer):
carpool = SchoolBuildingCarpoolSerializer()
class Meta:
model = ParentArrival
As you can see the carpool is defined as a nested serializer object and what I want is to be able to make a POST request to create a ParentArrival in this way (data as application/json):
{
...
"carpool": "http://localhost:8000/api/school-building-carpools/10/"
...
}
And receive the data in this way:
{
"carpool": {
"url": "http://localhost:8000/api/school-building-carpools/10/"
"name": "Name of the carpool",
...
}
}
Basically, I'm looking for a way to deal with nested serializers without having to send data as an object (but id or url in this case) in POST request, but receiving the object as nested in the serialized response.

I have been happy with my previous solution, but decided to look again and I think I have another solution that does exactly what you want.
Basically, you need to create your own custom field, and just overwrite the to_representation method:
class CarpoolField(serializers.PrimaryKeyRelatedField):
def to_representation(self, value):
pk = super(CarpoolField, self).to_representation(value)
try:
item = ParentArrival.objects.get(pk=pk)
serializer = CarpoolSerializer(item)
return serializer.data
except ParentArrival.DoesNotExist:
return None
def get_choices(self, cutoff=None):
queryset = self.get_queryset()
if queryset is None:
return {}
return OrderedDict([(item.id, str(item)) for item in queryset])
class ParentArrivalSerializer(serializers.HyperlinkedModelSerializer):
carpool = CarpoolField(queryset=Carpool.objects.all())
class Meta:
model = ParentArrival
This will allow you to post with
{
"carpool": 10
}
and get:
{
"carpool": {
"url": "http://localhost:8000/api/school-building-carpools/10/"
"name": "Name of the carpool",
...
}
}

It's simple.
As you know, Django appends "_id" to the field name in the ModelClass, and you can achieve it in the SerializerClass, and the original filed can also be achieved. All you have to do is like this
class ParentArrivalSerializer(serializers.HyperlinkedModelSerializer):
# ...
carpool_id = serializers.IntegerField(write_only=True)
carpool = SchoolBuildingCarpoolSerializer(read_only=True)
# ...
class Meta:
fields = ('carpool_id', 'carpool', ...)
And use carpool_id in POST request.

How about overriding the to_representation method?
class YourSerializer(serializers.ModelSerializer):
class Meta:
model = ModelClass
fields = ["id", "foreignkey"]
def to_representation(self, instance):
data = super(YourSerializer, self).to_representation(instance)
data['foreignkey'] = YourNestedSerializer(instance.foreignkey).data
return data

One way to do it is to keep 'carpool' as the default you get from DRF, and then add a read-only field for the nested object.
Something like this (I don't have time to test the code, so consider this pseudo-code. If you cannot get it to work, let me know, and will spend more time):
class ParentArrivalSerializer(serializers.HyperlinkedModelSerializer):
carpool_info = serializers.SerializerMethodField(read_only=True)
class Meta:
model = ParentArrival
fields = ('id', 'carpool', 'carpool_info',)
def get_carpool_info(self, obj):
carpool = obj.carpool
serializer = SchoolBuildingCarpoolSerializer(carpool)
return serializer.data
If your only nested object is carpool, I would also suggest switching to the regular ModelSerializer so carpool only shows the ID (10) and the nested object then can show the URL.
class ParentArrivalSerializer(serializers.ModelSerializer):
....
and then if it all works, you will be able to do a post with
{
"carpool": 10
}
and your get:
{
"carpool": 10
"carpool_info": {
"url": "http://localhost:8000/api/school-building-carpools/10/"
"name": "Name of the carpool",
...
}
}
I have never found another solution, so this is the trick I have used several times.

Django DRF multi model view

I wanna retrieve few models in a single request so i'll get:
{
"cars": [
{
"id": "1",
"name": "foo"
}
],
"trucks": [
{
"id": "1",
"name": "goo"
}
],
"bikes": [
{
"id": "1",
"name": "doo"
}
],
}
for that I've create a serializer:
class VehiclesSerializer(serializers.Serializer):
cars = CarSerializer(many=True, read_only=True)
trucks = TruckSerializer(many=True, read_only=True)
bikes = BikeSerializer(many=True, read_only=True)
and a view:
class VehiclesListView(generics.ListAPIView):
queryset = ???????
serializer_class = VehiclesSerializer
but as you can see, I haven't manage to figure out how to write the queryset.
Any help?
UPDATE:
Just to clarify my question. There is no Vehicle model.
That's why I'm NOT writing the regular
queryset = Vehicles.objects.all()

There are a few options I think. The two cleanest ones would be:
Have different endpoints for your models. This feels like the most RESTful approach to me.
Create a VehicleModel that is ForeignKey related to your other models. That should even work with the Serializer you have written.
The 2nd approach would look something like this for the models:
# models.py
class Vehicle(models.Model):
pass
class Truck(models.Model):
vehicle = models.ForeignKey(Vehicle, related_name='trucks')
....
And like this for the views:
#views.py
class VehiclesListView(generics.ListAPIView):
queryset = Vehicle.objects.prefetch_related('cars', 'trucks', 'bikes').all()
serializer_class = VehiclesSerializer
Note on the prefetch_related() in there: Django will use four DB queries to get your objects, one for each related model and one for the main model. If you use Vehicle.objects.all() by itself, the Serializer will create a DB requests for every Vehicle it encounters. See Django docs here
If you don't want to do that, you can always override ListAPIView.list with your custom logic, even bypass the serializer completely:
class VehiclesListView(generics.ListAPIView):
def list(self, request, *args, **kwargs):
cars = Cars.objects.values('id', 'name')
trucks = Trucks.objects.values('id', 'name')
bikes = Bikes.objects.values('id', 'name')
out = {
'trucks': trucks,
'cars': cars,
'bikes': bikes,
}
return Response(out)
Note on using values() instead of all(): You don't really use any other model fields in your serializer, so there's no use in querying extra fields. Docs

You should really read the API Documentation.
queryset = Vehicles.objects.all();
or to get random 100 or 10 objects:
Vehicles.objects.all().order_by('?')[:100]
or
Vehicles.objects.all().order_by('?')[:10]

queryset = Vehicles.objects.all()
Or if you need to filter on datetime or request properties.
def get_queryset(self):
return Vehicles.objects.all()

The best that I've got was without using generics:
class VehiclesListView(APIView):
def get(self, request, *args, **kwargs):
ser = VehiclesSerializer({
'cars': Car.objects.all(),
'trucks': Truck.objects.all(),
'bikes': Bike.objects.all()
})
return JsonResponse(ser.data)
Thanks all for your help :)

The easiest way is to use DjangoRestMultipleModels
The documentation is beautiful.
In your case the view would look like this:
from drf_multiple_model.views import MultipleModelAPIView
class VehicleView(MultipleModelAPIView):
queryList = [
(Car.objects.all(),CarSerializer), #(queryset,Serializer)
(Truck.objects.all(),TruckSerializer),
(Bike.objects.all(), BikeSerializer),
]
Hope this helps someone..