We Keep Coding

Filter Django rest framework get request by foreign key (MultipleObjectsReturned)

I have a database table called Supplier that has a foreign key of User, each User has their own Suppliers. I got the get request working so that it returns all Suppliers in the entire table, but I can not find a way to filter it so I only receive the Suppliers associated with the User requested.
I am accessing this request by this URL:
http://localhost:8000/pm/getsuppliers/primary-key-of-user/
models.py:
class UserProfile(models.Model):
user = models.OneToOneField(User,on_delete=models.CASCADE)
bio = models.CharField(max_length=200)
email = models.CharField(max_length=200)
class Supplier(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
name = models.CharField(max_length=200)
phone = models.IntegerField()
email = models.EmailField(max_length=200)
views.py:
class getsuppliers(viewsets.ModelViewSet):
queryset = Supplier.objects.all()
serializer_class = GetSuppliersSerializer
lookup_field = 'user'
serializers.py:
class GetSuppliersSerializer(serializers.ModelSerializer):
class Meta:
model=Supplier
fields=['pk','user','name','email','phone']
The error I am receiving:
ERROR: pm.models.Supplier.MultipleObjectsReturned: get() returned more than one Supplier -- it returned 10!
I have done some searching on this error and they are saying to use .filter instead of .all in the view, but I am not sure how to make it return ALL Suppliers for the requested User, this seems like it would only return 1. Maybe I am wrong, hopefully someone has an easy solution!

You'll have to set the serializer's model (inside Meta) to User, and add in a supplier_set field:
class GetUserSuppliersSerializer(serializers.ModelSerializer):
supplier_set = SupplierSerializer(read_only=True, many=True)
class Meta:
model = User
fields = ['supplier_set']
class SuppliersSerializer(serializers.ModelSerializer):
class Meta:
model = Supplier
fields = ['pk','user','name','email','phone']
And also change the viewset queryset to get users.
Edit:
To answer the question in the comment, there are a few different ways to do that based on what you need, one way is to add a to_representation method in your GetUserSuppliersSerializer as such:
def to_representation(self, instance):
response = super().to_representation(instance)
response["supplier_set"] = sorted(response["supplier_set"], key=lambda x: x["pk"])
return response

How to give access for a model object to a specific user in Django

I am doing an online classroom project in Django where I created a model named create_course which is accessible by teachers. Now I am trying to design this as the teacher who creates a class only he can see this after login another teacher shouldn't see his classes and how to add students into that particular class I created
the course model
class course(models.Model):
course_name = models.CharField(max_length=200)
course_id = models.CharField(max_length=10)
course_sec = models.IntegerField()
classroom_id = models.CharField(max_length=50,unique=True)
views.py
def teacher_view(request, *args, **kwargs):
form = add_course(request.POST or None)
context = {}
if form.is_valid():
form.save()
return HttpResponse("Class Created Sucessfully")
context['add_courses'] = form
return render(request, 'teacherview.html', context)
forms.py
from django import forms
from .models import course
class add_course(forms.ModelForm):
class Meta:
model = course
fields = ('course_name', 'course_id', 'course_sec', 'classroom_id')

Add one more field in course model that establish relationship with User model. Hence you can get the details about the teacher who has created course.
from django.contrib.auth.models import User
class course(models.Model):
course_name = models.CharField(max_length=200)
course_id = models.CharField(max_length=10)
course_sec = models.IntegerField()
classroom_id = models.CharField(max_length=50,unique=True)
created_by = models.ForeignKey(User, on_delete=models.CASCADE)
In your view function, you can check whether logged in user is same as the created of the requested course.
def teacher_view(request, *args, **kwargs):
# since this is course specific view, you will be passing an identiier or pk of the course as an argument to this function.
course_obj = Course.objects.get(id="identifier")
if request.user == course_obj.created_by:
# logged in user is same as the creator of the course
else:
# redirect
I would prefer creating permissions and having those in specific models. You can give it a try with that too. Let me know, if it doesn't work.

How to obtain a user instance in django application

I'm trying to obtain a user instance for the profile page in django app but I'm finding some difficulties implementing that functionality. I have the following blocks of code:
models.py
class Profile(models.Model):
user = models.OneToOneField(settings.AUTH_USER_MODEL, primary_key=True, on_delete=models.CASCADE, default="")
image = models.ImageField(upload_to="images/user_profile_pics/", default="images/default_profile_pics/default.jpg")
firstname = models.CharField(max_length=50)
lastname = models.CharField(max_length=50)
def __str__(self):
return f'{self.lastname} profile'
serializers.py
class user_profile_serializer(serializers.ModelSerializer):
class Meta:
model = Profile
fields = '__all__'
views.py
class user_profile(generics.GenericAPIView):
serializer_class = user_profile_serializer
def get(self, request, *args, **kwargs):
user = self.get_serializer(request.user).data
if request.user.is_authenticated:
return Response(user, status=status.HTTP_200_OK)
else:
pass
urls.py
urlpatterns = [
path('profile/', user_profile.as_view(), name="user-profile"),
]
When ever I assess the profile url, I get an error message 'AnonymousUser' object has no attribute 'data' I have tried a couple of approaches but none worked. Please, how do I obtain a specific user from the database?

request.user is AnonymousUser when the user is not logged in. In that case that object does not have data attribute. Hence the error you get. One thing you can do is check request.user.is_authenticated and if the user is not authenticated, return some other value / or None. And try logging in before trying to access the user.data value.

Django Form: Only show manytomany objects from logged in user

The current problem is that my form shows the logged in user all Portfolios ever created. The form should only show portfolios that the logged-in user created.
Something like this:
associated_portfolios manytomany field = ...objects.filter(user=user_id)
I'm not sure if this should be implemented in the forms.py or views.py and if so how. I've been going through the django documentation and found 'formfield_for_manytomany' but not sure if this is only meant for admin.
Models.py
class Portfolio(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
name = models.CharField(max_length=20)
description = models.CharField(max_length=250, blank=True, null=True)
class Post(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
title = models.CharField(max_length=50)
body = RichTextUploadingField(blank=True, null=True)
associated_portfolios = models.ManyToManyField(Portfolio, blank=True)
created_on = models.DateField(auto_now_add=True, editable=False)
Views.py
class PostCreate(CreateView):
model = Post
form_class = PostCreateForm
def formfield_for_manytomany(self, db_field, request, **kwargs):
self.fields['associated_portfolios'] = Portfolio.objects.filter(user=self.request.user)
return super().formfield_for_manytomany(db_field, request, using=self.using, **kwargs)
forms.py
class PortfolioCreateForm(ModelForm):
class Meta:
model = Portfolio
fields = ['user', 'name', 'description']
class PostCreateForm(ModelForm):
class Meta:
model = Post
fields = ['user', 'title', 'body', 'category', 'associated_portfolios']

Since you're using a ModelForm, the associated_protfolios field will be a ModelMultipleChoiceField [docs]. This field has a queryset attribute [docs]. We want to modify that attribute.
Django's CreateView has a method get_form, which in this case will grab your PostCreateForm. This is a good spot to filter the field's queryset, since we have access to the user:
class PostCreate(CreateView):
model = Post
form_class = PostCreateForm
def get_form(self, *args, **kwargs):
form = super().get_form(*args, **kwargs) # Get the form as usual
user = self.request.user
form.fileds['associated_portfolios'].queryset = Portfolio.objects.filter(user=user)
return form

Did you try this
self.fields['associated_portfolios'] = Post.objects.filter(associated_portfolios__portfolio__user=request.user)
OR
user_posts = Post.objects.filter(user=request.user)
self.fields['associated_portfolios'] = user_posts.associated_portfolios.all()
read more about M2M relationships querying here, because I think your problem may be with it.
Also, I'm not sure about your actual data maybe it's right and it gives a correct result as filtering Portfolio model against current user to get its objects looks right for me, but anyway double check everything again.
And as a final note, add related_name to your model fields so you can use it easily for reverse relations rather than going with Django's default naming, it will be clearer and give a better understanding.

Django Many-to-one with Users Unique Constraint Failing

I am working on a project where I have a class called Investment. Basically, a user can can have many investments, and an investment can consist of many users. As such my models.py looks like this:
# Not sure if this class is relevant to my question
class UserProfile(models.Model):
user = models.OneToOneField(User)
first_name = models.CharField(max_length=24)
last_name = models.CharField(max_length=24)
phone_number = models.CharField(max_length=12)
account_type = models.CharField(max_length=55, choices=ACCOUNT_TYPES)
def __str__(self):
return self.user.username
class Investment(models.Model):
user = models.ForeignKey(User)
offered_fund = models.ForeignKey(OfferedFunds)
amount = models.IntegerField(default=0)
purchase_date = models.DateTimeField(auto_now_add=True)
def __int__(self):
return self.offered_fund.fund_name.name
and my forms.py:
class InvestmentForm(forms.ModelForm):
class Meta:
model = Investment
fields = ('offered_fund','amount')
exclude = ['user']
finally, my views.py:
if form.is_valid():
instance = form.save(commit=False)
instance.user = request.user
instance.save()
So the way it works when deployed is the user selects an offered_fund, and enters an amount then hits submit. When I do this once, it registers and I can see it in the Django Administration page. However, the second time I try to do it (selecting the same or a different offered_fund) I get the error:
UNIQUE constraint failed: users_investment.user_id
Any idea on how I can solve this? Thanks.

You're using a ForeignKey relationship which only allows one User object for each Investment.
You should be using a ManyToManyField which allows more than one User per Investment.