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Django Nested Serializer - Return Null Field if condition is fullfiled

I have a nested serializes, which content I need to return as Null in case of the parent-serializer field "is_profile_private" (a boolean) is True.
I tried using get_queryset in order to filter the User Profile but no progress was made.
Tried using SerializerMethordField() and get_profile() but Django complained about UserProfileSerializer type of object not being allowed to be serialized.
serializers.py
class UserProfileSerializer(UserSerializer):
height = serializers.SerializerMethodField()
class Meta:
model = UserProfile
fields = (
"bio",
"gender",
"custom_gender",
"non_binary_list",
"birthdate",
"avatar",
"height",
"hometown",
"zodiac_sign",
"language",
)
#staticmethod
def get_height(obj):
return {"value": obj.height, "unit": obj.height_unit}
class SimpleUserSerializer(UserSerializer):
profile = UserProfileSerializer(source="user", required=False)
class Meta:
model = User
fields = (
"id",
"name",
"username",
"is_profile_private",
"date_joined",
"profile",
)
views.py
class UserProfileAPIView(RetrieveModelMixin, UpdateModelMixin, GenericViewSet):
lookup_field = "id"
queryset = User.objects.all()
serializer_class = SimpleUserSerializer
http_method_names = ["get"]
#staticmethod
def get(request, *args, **kwargs):
return User.objects.get(id=str(request.data))

You can use SerializerMethodField:
class SimpleUserSerializer(UserSerializer):
profile = serializers.SerializerMethodField()
class Meta:
model = User
fields = (
"id",
"name",
"username",
"is_profile_private",
"date_joined",
"profile",
)
def get_profile(self, obj):
if obj.is_profile_private:
return None
return UserProfileSerializer(obj.user).data
please note that you should return serializer's data, not serializere itself.

POST with an ID and GET the nested object does not work in django at the same time in ModelSerializer

I have spent already a couple of days researching about this issue in similar questions and I am not able to get a solution. This should be something simple, I have a model:
model.py
class Item(models.Model):
"""Class to represent an item..."""
label = models.TextField(null=True)
name = models.TextField()
category = models.ForeignKey( "Category", on_delete=models.SET_NULL,
null=True, default=DEFAULT_CATEGORY_ID)
class Category(models.Model):
"""Class to represent the category of an Item. Like plants, bikes..."""
name = models.TextField()
description = models.TextField(null=True)
view.py
class ItemViewset(viewsets.ModelViewSet): # pylint: disable=too-many-ancestors
"""API Endpoint to return the list of items"""
queryset = Item.objects.all()
serializer_class = ItemSerializer
serializer.py
class ItemSerializer(serializers.ModelSerializer):
"""Serializer for Item."""
category = CategorySerializer(read_only=True)
class Meta: # pylint: disable=too-few-public-methods
"""Class to represent metadata of the object."""
model = Item
fields = [ 'id', 'label', 'name', 'category']
read_only_fields = ['id']
# def to_representation(self, instance):
# ret = super().to_representation(instance)
# ret['category'] = CategorySerializer(instance.category).data
# return ret
def create(self, request):
# Look up objects by arbitrary attributes.
# You can check here if your students are participating
# the classes and have taken the subjects they sign up for.
category = get_object_or_404(Category(), id=request.data.get('category'))
serializer = self.get_serializer(data=request.data)
serializer.is_valid(raise_exception=True)
serializer.save(category=category)
headers = self.get_success_headers(serializer.data)
return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
If I have the line category = CategorySerializer(read_only=True) commented the nested get won't work, for example for a curl to an object. I will get just de id of the structure. If I uncomment it like it is in the example I get the right response:
{
"id": 60,
"label": null,
"name": "Delete me",
"category": {
"id": 1,
"name": "IT"
}
}
But then the post with id will not work, the category will be set to null.
How can I get both working at the same time?
Update: This is the post I want to do:
{
"label": "00000003",
"name": "Delete me",
"category": 1,
}

You can override the to_represention method of your serializer
class ItemSerializer(serializers.ModelSerializer):
"""Serializer for Item."""
class Meta: # pylint: disable=too-few-public-methods
"""Class to represent metadata of the object."""
model = Item
fields = [ 'id', 'label', 'name', 'category']
read_only_fields = ['id']
def to_representation(self, instance):
data = super().to_representation(instance)
data["category"] = CategorySerializer(instance.category).data
return data

Insert data on OneToOneField using django-rest-framework

I am new to this django-rest-framework, my problem is how am I going to insert a data with one-to-one relationship in the views.py.
I can do the normal way of inserting data like the one below,
def post(self, request,format=None):
p = Person()
p.firstname = "John"
p.middlename = "K"
p.lastname = "Rambo"
p.save()
e = Employee()
e.code = "emp-002"
e.person_id = p.id
e.save()
I cannot do the approach above because I want to learn more about DRF.
To give you more idea please see below :
I have this model
class Person(models.Model):
firstname = models.CharField(max_length=150, default="")
middlename = models.CharField(max_length=150, default="")
lastname = models.CharField(max_length=150, default="")
class Employee(models.Model):
person = models.OneToOneField(Person, on_delete=models.CASCADE,primary_key=True)
code = models.CharField(max_length=100, default="")
I have this serializer
class PersonSer(serializers.ModelSerializer):
class Meta:
model = Person
fields = (
'id',
'firstname',
'middlename',
'lastname',)
class EmployeeSer(serializers.ModelSerializer):
person = PersonSer()
class Meta:
model = Employee
fields = ('code','person')
I have this view
class SaveData(APIView):
#transaction.atomic
def post(self,request, format=None):
p = PersonSer(data=request.data)
if p.is_valid():
p.save()
request.data['person'] = p.data['id']
request.data['code'] = "Emp-"+str(p.data['id'])
"""
I expect request.data now equal to
{
'person' : 102, # we assume the newly created person id == 102
'code' : 'Emp-102',
'firstname' : 'John',
'middlename' : 'K.',
'lastname' : 'Rambo'
}
"""
es = EmployeeSer(data=request.data)
if es.is_valid():
es.save()
else:
print(es.errors) # {'person': [ErrorDetail(string='This field is required.', code='required')]}
"""
I also tried this,
es = EmployeeSer(data={'person' : p.data, 'code' : 'Sample code'})
if es.is_valid():
es.save()
else:
print(es.errors) #{'person': {'fullname': [ErrorDetail(string='This field may not be blank.',code='blank')], ]}}
"""
return Response({'message':'okay'})
The request.data is a formData, the value is
{
'firstname' : 'John',
'middlename' : 'K.',
'lastname' : 'Rambo'
}

You can override the create method of the PersonSer to achieve this.
class PersonSer(serializers.ModelSerializer):
...
def create(self, validated_data):
person = Person.objects.create(**validated_data)
Employee.objects.create(person=person, code=f"Emp-{person.id}")
return person
And you can simplify your view to:
...
#transaction.atomic
def post(self,request, format=None):
p = PersonSer(data=request.data)
p.is_valid(raise_exception=True)
p.save()
return Response({'message':'okay'})
...
raise_expection=True will cause serializer to raise ValidationError exception if there are validation errors.

Python DRF PrimaryKeyRelatedField to use uuid instead of PK

I'm writing a Django REST Framework API.
My models have default Django PK for internal use AND uuid field for external reference.
class BaseModel(models.Model):
uuid = models.UUIDField(default=uuid.uuid4, editable=False)
class Event(BaseModel):
title = models.TextField()
location = models.ForeignKey('Location', null=True, on_delete=models.SET_NULL)
class Location(BaseModel):
latitude = models.FloatField()
longitude = models.FloatField()
And my serializers:
class BaseSerializer(serializers.ModelSerializer):
default_fields = ('uuid',)
class EventSerializer(BaseSerializer):
class Meta:
model = Event
lookup_field = 'uuid' # This does not work
fields = BaseSerializer.default_fields + ('title', 'location',)
class LocationSerializer(BaseSerializer):
class Meta:
model = Location
lookup_field = 'uuid' # This does not work
fields = BaseSerializer.default_fields + ('latitude', 'longitude',)
This works fine, here is what I got when I retrieve an Event:
{
"uuid": "ef33db27-e98b-4c26-8817-9784dfd546c6",
"title": "UCI Worldcup #1 Salzburg",
"location": 1 # Note here I have the PK, not UUID
}
But what I would like is:
{
"uuid": "ef33db27-e98b-4c26-8817-9784dfd546c6",
"title": "UCI Worldcup #1 Salzburg",
"location": "2454abe7-7cde-4bcb-bf6d-aaff91c107bf" # I want UUID here
}
And of course I want this behavior to work for all my ForeignKeys and ManyToMany fields.
Is there a way to customize the field used by DRF for nested models ?
Thanks !

from django.utils.translation import ugettext_lazy as _
from django.core.exceptions import ObjectDoesNotExist
from rest_framework.relations import RelatedField
from django.utils.encoding import smart_text
class UUIDRelatedField(RelatedField):
"""
A read-write field that represents the target of the relationship
by a unique 'slug' attribute.
"""
default_error_messages = {
'does_not_exist': _('Object with {uuid_field}={value} does not exist.'),
'invalid': _('Invalid value.'),
}
def __init__(self, uuid_field=None, **kwargs):
assert uuid_field is not None, 'The `uuid_field` argument is required.'
self.uuid_field = uuid_field
super().__init__(**kwargs)
def to_internal_value(self, data):
try:
return self.get_queryset().get(**{self.uuid_field: data})
except ObjectDoesNotExist:
self.fail('does_not_exist', uuid_field=self.uuid_field, value=smart_text(data))
except (TypeError, ValueError):
self.fail('invalid')
def to_representation(self, obj):
return getattr(obj, self.uuid_field)
Sample Usage:
class ProductSerializer(serializers.ModelSerializer):
category = UUIDRelatedField(
queryset=Category.objects.all(),
uuid_field='alias'
)
class Meta:
model = Product
fields = (
'id',
'alias',
'name',
'category',
)
read_only_fields = (
'id',
'alias',
)
Note that as of Django version 4, smart_text and ugettext_lazy were removed, use smart_str and gettext_lazy instead of them:
from django.utils.encoding import gettext_lazy
from django.utils.encoding import smart_str

A friend of mine send me this solution:
It works with all my related objects.
from rest_framework import serializers
from rest_framework.relations import SlugRelatedField
class UuidRelatedField(SlugRelatedField):
def __init__(self, slug_field=None, **kwargs):
slug_field = 'uuid'
super().__init__(slug_field, **kwargs)
class BaseSerializer(serializers.ModelSerializer):
default_fields = ('uuid',)
serializer_related_field = UuidRelatedField
class Meta:
pass

For nested model fields you can use the source argument in a serializer like this
class EventSerializer(BaseSerializer):
location = serializers.CharField(source='location.uuid')
class Meta:
model = Event
lookup_field = 'uuid' # This does not work
fields = BaseSerializer.default_fields + ('title', 'location',)

can not use different fields for each object in serializer django rest framework

I want to create a udemy like web app and using django rest framework for the backend and mysql as database.
i have a model named 'Lessons' that contains list of all lessons and one of the fields is 'video-link'. also i have another model names Purchases that have two ForeignKey fields :Users and Lessons. i want to show the Lessons to all users but for the download field i have to lookup the pair (User , Lesson) in Purchases and if He has the course i will show him the download field.
My View Set
class LessonsViewSet(viewsets.ModelViewSet):
queryset = models.Assignments.objects.all()
authentication_classes = (TokenAuthentication,)
def get_serializer_class(self):
if self.request.user.is_staff :
print(self.request.user)
return serializers.FullAccessLessonsSerializer
elif self.request.user.is_active:
return serializers.PartialAccessLessonsSerializer
print(self.request.user)
return serializers.BasicAccessLessonsSerializer
My Serializers
Full access for admins:
class FullAccessLessonsSerializer(serializers.ModelSerializer):
class Meta:
model = models.Assignments
fields = ('id', 'title', 'description', 'dllink' )
Basic access for unauthenticated users:
class BasicAccessLessonsSerializer(serializers.ModelSerializer):
class Meta:
model = models.Assignments
fields = ('id', 'title', 'description')
and partial access for students :
class PartialAccessAssignmentsSerializer(serializers.ModelSerializer):
"""A serializer for all Lessons"""
def __init__(self, *args, **kwargs):
fields = kwargs.pop('fields', None)
super(PartialAccessAssignmentsSerializer, self).__init__(*args,**kwargs)
print(self.fields.get('id'))
self.fields.pop('dllink')
class Meta:
model = models.Assignments
fields = ('id','title','description','dllink' )
I have done anything I could found but I can not figure it out. I either an get error or removing all dl links.

If you want dllink is None when user can't access.use this:
class FullAccessLessonsSerializer(serializers.ModelSerializer):
dllink = serializers.SerializerMethodField()
def get_prescription_accept(self, instance):
result = True # lookup the pair (User , Lesson) in Purchases
if result:
return instance.dllink
else:
return ''
class Meta:
model = models.Assignments
fields = ('id', 'title', 'description', 'dllink' )
If you want pop dllink from data,use:
class FullAccessLessonsSerializer(serializers.ModelSerializer):
def to_representation(self, instance):
data = super(FullAccessLessonsSerializer, self).to_representation(instance)
result = True # lookup the pair (User , Lesson) in Purchases
if not result:
data.pop('dllink')
return data
class Meta:
model = models.Assignments
fields = ('id', 'title', 'description', 'dllink' )