Develop Reference

Django,update the same row field in model getting data from serializer

I have this model:
class AgentDetail(MethodID):
first_name = models.CharField(max_length=50, blank=True, null=True, unique=True)
last_name = models.CharField(max_length=50, unique=True, null=True)
email = models.EmailField(null=False)
authen_method = models.ForeignKey(AuthMethodID, on_delete=models.CASCADE)
country_code = models.BigIntegerField(default=1)
mobile_number = models.BigIntegerField(null=False)
sms_provider = models.CharField(max_length=50, null=True)
active_status = models.BooleanField(default=True)
created_time = models.DateTimeField(default=now, editable=False)
created_by = models.CharField(max_length=50)
updated_time = models.DateTimeField(auto_now=True)
updated_by = models.CharField(max_length=50)
and this serializer:
class AgentSerializer(serializers.ModelSerializer):
class Meta:
model = AgentDetail
fields = [
"first_name",
"last_name",
"email",
"authen_method",
"mobile_number",
"sms_provider",
]
and this views.py:
#api_view(["POST"])
def create_agent(request):
if request.method == "POST":
serializer = AgentSerializer(data=request.data, many=False)
if serializer.is_valid():
serializer.save()
request_data = serializer.data
# AgentDetail.objects.update_or_create(
# created_by=request_data["first_name"] + request_data["last_name"],
# updated_by=request_data["first_name"] + request_data["last_name"],
# )
return Response(status=status.HTTP_200_OK)
error = Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
return error
As in serializer I'm not passing created_by field and I need that field gets value of first_name+last_name which are coming from serializer data.I'm new to DRF.

as said in docs you can pass additional attributes to save method.
views.py
#api_view(["POST"])
def create_agent(request):
if request.method == "POST":
serializer = AgentSerializer(data=request.data, many=False)
if serializer.is_valid():
request_data = serializer.validated_data
serializer.save(
created_by=request_data["first_name"] + request_data["last_name"],
updated_by=request_data["first_name"] + request_data["last_name"],
)
return Response(status=status.HTTP_200_OK)
error = Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
return error

you can access the validated_data in create method, and add any extra data you want.
serializer.py
class AgentSerializer(serializers.ModelSerializer):
...
def create(self, validated_data):
first_name = validated_data.get('first_name', '')
last_name = validated_data.get('last_name', '')
validated_data.update(dict(
created_by=first_name+last_name,
updated_by=first_name+last_name
))
return super().create(validated_data)

Python Django | POST method with nested object. NOT NULL constraint failed

My point is to implement the post method with a nested object which has just ID. When I use all fields of a nested object post method works fine. But I'd like to pass just one field and it is ID, other fields gotta be unrequired
Now I'm getting the error like
NOT NULL constraint failed: article_article.author_id
models.py
class Author(models.Model):
first_name = models.CharField(max_length=20, blank=True, null=True)
last_name = models.CharField(max_length=20, blank=True, null=True)
nickname = models.CharField(max_length=20, blank=True, null=True)
def __str__(self):
return self.nickname
class Article(models.Model):
title = models.CharField(max_length=120, unique=True)
description = models.TextField(blank=True)
author = models.ForeignKey(Author, on_delete=models.CASCADE, related_name='articles')
created_at = models.DateTimeField(auto_now_add=True, blank=True)
updated_at = models.DateTimeField(auto_now=True, blank=True)
def __str__(self):
return self.title
views.py
class ArticleView(APIView):
def get(self, request, pk=None):
if pk:
article = Article.objects.get(pk=pk)
serializer = ArticleSerializer(article, many=False)
else:
articles = Article.objects.all()
serializer = ArticleSerializer(articles, many=True)
return Response(serializer.data)
def post(self, request):
data = request.data
serializer = ArticleSerializer(data=data)
if serializer.is_valid(raise_exception=True):
article_saved = serializer.save()
return Response({"success": "Article '' created successfully".format(article_saved.title)},
status=status.HTTP_201_CREATED)
serializers.py
class AuthorSerializer(serializers.Serializer):
first_name = serializers.CharField(required=False)
last_name = serializers.CharField(required=False)
nickname = serializers.CharField(required=False)
class ArticleSerializer(serializers.Serializer):
title = serializers.CharField(max_length=120)
description = serializers.CharField()
author = AuthorSerializer(required=False)
def create(self, validated_data):
author_data = validated_data.pop('author', None)
if author_data:
author = Author.objects.get_or_create(**author_data)[0]
validated_data['author'] = author
return Article.objects.create(**validated_data)

I got it. I should just have added to a serializer the field ID
class AuthorSerializer(serializers.Serializer):
first_name = serializers.CharField(required=False)
last_name = serializers.CharField(required=False)
nickname = serializers.CharField(required=False)
id = serializers.IntegerField()

Cannot successfully pass foreign_key reference to PUT request in Django REST

I am getting into Django REST and I am trying to use it for a backend of type of crypto currency tracker for my use. However I have been stuck on an issue for a few days..
I have the following models.py:
class Coin(models.Model):
sign = models.CharField(max_length=50, primary_key=True) # capitalize all entries
name = models.CharField(max_length=50, null=False)
amount = models.DecimalField(max_digits=20, decimal_places=2, null=False)
price_each = models.DecimalField(max_digits=20, decimal_places=2, null=False)
purchased_on = models.DateField(null=True)
def __str__(self):
return self.sign
def save(self, *args, **kwargs):
self.sign = self.sign.upper()
return super(Coin, self).save(*args, **kwargs)
class Price(models.Model):
coin = models.ForeignKey(Coin, related_name="prices", on_delete=models.CASCADE)
day_date = models.DateField(null=False)
current_price = models.DecimalField(max_digits=20, decimal_places=2, null=False)
def __str__(self):
timestamp = self.day_date.strftime("%d-%b-%Y")
return timestamp
and serializers.py:
class PriceSerializer(serializers.ModelSerializer):
coin_sign = serializers.PrimaryKeyRelatedField(queryset=Coin.objects.all(), source='coin.sign')
class Meta:
model = Price
fields = ['id', 'day_date', 'current_price', 'coin_sign']
def create(self, validated_data):
return Price.objects.create(**validated_data)
class CoinSerializer(serializers.ModelSerializer):
prices = PriceSerializer(many=True, read_only=False)
class Meta:
model = Coin
fields = ['sign', 'name', 'amount', 'price_each', 'purchased_on', 'prices']
def create(self, validated_data):
return Coin.objects.create(**validated_data)
I am having trouble defining a view with PUT to create a new price entry in view.py:
class AddPrice(APIView):
def put(self, request, sign, format=None):
coin = get_object_or_404(Coin, sign=sign.upper())
request.data['coin_sign'] = coin
serializer = PriceSerializer(data=request.data)
if serializer.is_valid():
serializer.save()
return Response(serializer.data, status=status.HTTP_201_CREATED)
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
Here is the URL where I try to hit the PUT endpoint:
http://127.0.0.1:8000/crypto/coins/cro/add_price/
with following body:
{
"day_date": "2021-12-04",
"current_price": "420.69"
}
and the urlpattern from my_app/urls.py:
path('', views.index, name='index'), # http://127.0.0.1:8000/crypto/
path('coins/', views.Coins.as_view(), name='all_coins'),
path('coins/<str:sign>/', views.CoinInfo.as_view(), name='coin_info'),
path('coins/<str:sign>/add_price/', views.AddPrice.as_view(), name='add_price'),
I understand that I am passing a an object's representation of itself with that instead of the actual object and I cannot link the Price to the Coin properly because of that:
Cannot assign "{'sign': <Coin: CRO>}": "Price.coin" must be a "Coin" instance.
How do I create a Price entity from the endpoint successfully?
Thank you for reading!

I managed to create a resource with a POST request using my endpoint.
It is ugly and it does not use the serializer's validation and I probably would not recommend it.
models.py:
class Coin(models.Model):
sign = models.CharField(max_length=50, primary_key=True) # capitalize all entries
name = models.CharField(max_length=50, null=False)
amount = models.DecimalField(max_digits=20, decimal_places=2, null=False)
price_each = models.DecimalField(max_digits=20, decimal_places=2, null=False)
purchased_on = models.DateField(null=True)
# def __str__(self):
# return self.sign
def save(self, *args, **kwargs):
self.sign = self.sign.upper()
return super(Coin, self).save(*args, **kwargs)
class Price(models.Model):
coin = models.ForeignKey(Coin, related_name="prices", on_delete=models.CASCADE)
day_date = models.DateField(null=False)
current_price = models.DecimalField(max_digits=20, decimal_places=2, null=False)
serializers.py:
class PriceSerializer(serializers.ModelSerializer):
coin_sign = serializers.PrimaryKeyRelatedField(queryset=Coin.objects.all(), source='coin.sign')
class Meta:
model = Price
fields = ['id', 'day_date', 'current_price', 'coin_sign']
def create(self, validated_data):
return Price.objects.create(**validated_data)
class CoinSerializer(serializers.ModelSerializer):
prices = PriceSerializer(many=True, read_only=True)
class Meta:
model = Coin
fields = ['sign', 'name', 'amount', 'price_each', 'purchased_on', 'prices']
def create(self, validated_data):
return Coin.objects.create(**validated_data)
my view in vies.py:
class AddPrice(APIView): # not using serializer's validation, but will leave it as is for now
def post(self, request, sign):
coin = get_object_or_404(Coin, sign=sign.upper())
day_date = request.data.get('day_date')
current_price = request.data.get('current_price')
price = Price(coin=coin, day_date=day_date, current_price=current_price)
price.save()
serializer = PriceSerializer(price, context={'request': request})
return Response(serializer.data, status=status.HTTP_201_CREATED)

How can I get user from serializer?

I am trying to override perform_update in my views, get user from serializer and assign it to updated_by in my Category model.
class Category(models.Model):
name = models.CharField(max_length=80)
created_at = models.DateTimeField(auto_now_add = True, null = True)
created_by = CurrentUserField()
updated_at = models.DateTimeField(auto_now = True, null = True)
updated_by = models.ForeignKey(User, default = None, blank=True, null=True, on_delete=models.DO_NOTHING, related_name="updated_by")
deleted_at = models.DateTimeField(null = True)
deleted_by = models.ForeignKey(User, default = None, blank=True, null=True, on_delete=models.DO_NOTHING, related_name='deleted_by')
class Meta:
verbose_name_plural = "Categories"
def __str__(self):
return self.name
def soft_delete(self, deleter):
self.deleted_by = deleter
self.deleted_at = timezone.now()
self.save()
serializer
class CategorySerializer(serializers.ModelSerializer):
class Meta:
model = Category
fields = "__all__"
views:
class CategoryView(viewsets.ModelViewSet):
serializer_class = CategorySerializer
queryset = Category.objects.all()
def get_permissions(self):
if self.request.method == "GET":
self.permission_classes = (AllowAny, )
else:
self.permission_classes = (IsAdminUser, )
return super(CategoryView, self).get_permissions()
def perform_update(self, serializer):
instance = self.get_object()
instance.updated_by = username
serializer.save()
def destroy(self, request, *args, **kwargs):
instance = self.get_object()
deleter = self.request.user
self.perform_destroy(instance, deleter)
return Response(status=status.HTTP_204_NO_CONTENT)
def perform_destroy(self, instance, deleter):
instance.soft_delete(deleter)

User is available from request, not serializer. You are already using self.request.user in destroy() and you can do the same thing in perform_update()
def perform_update(self, serializer):
serializer.save(updated_by=self.request.user)

DRF: Database not updating

Following are my files. It is simply adding products based on subcategories and categories. Everything is working fine but the data is not being saved in the database. I am not sure where I am going wrong.
models.py
from django.db import models
class Category(models.Model):
category = models.CharField(max_length=200)
parent = models.ForeignKey('self', blank=True, null=True, related_name='children')
class Meta:
unique_together = ('parent' , 'category')
def __str__(self):
return self.category
class SubCategory(models.Model):
subcategory = models.CharField(max_length=200)
category = models.ForeignKey('Category', null=True, blank=True)
parent = models.ForeignKey('self', blank=True, null=True, related_name='subchilren')
class Meta:
unique_together = ('parent' , 'subcategory')
def __str__(self):
return self.subcategory
class Product(models.Model):
name = models.CharField(max_length=200)
category = models.ForeignKey('Category', null=True, blank=True)
subcategory = models.ForeignKey('SubCategory', null=True, blank=True)
def __str__(self):
return self.name
views.py
class AddProducts(APIView):
serializer_class = AddProductsSerializer
def post(self, request, format=None):
data = request.data
serializer = AddProductsSerializer(data=data)
if serializer.is_valid(raise_exception=True):
new_data = serializer.data
return Response(new_data)
return Response(serializer.errors, status=HTTP_400_BAD_REQUEST)
serializers.py
class AddProductsSerializer(serializers.ModelSerializer):
class Meta:
model = Product
fields = ('id', 'name', 'category', 'subcategory')
def create(self, validated_data):
return Product.objects.create(**validated_data)
def update(self, instance, validated_data):
instance.name = validated_data.get('name', instance.name)
instance.category = validated_data.get('category', instance.category)
instance.subcategory = validated_data.get('subcategory', instance.subcategory)
instance.save()
return instance

if serializer.is_valid(raise_exception=True):
serializer.save()
new_data = serializer.data
return Response(new_data)
add serializer.save() will call serializer create method when serializer has no instance.