So basically I have a django model that has a ManyToManyField of friends and two methods that run on it. Here are my files:
Models.py:
from django.db import models
from django.contrib.auth.models import User
class Profile(models.Model):
first_name = models.CharField(max_length=50, blank=True)
last_name = models.CharField(max_length=50, blank=True)
user = models.OneToOneField(User, on_delete=models.CASCADE)
friends = models.ManyToManyField(User, blank=True, related_name='friends')
def friends_list(self):
return self.friends.all()
def number_of_friends(self):
return self.friends.all().count()
Serialzers.py:
from rest_framework import serializers
from .models import Profile
class ProfileSerializer(serializers.ModelSerializer):
class Meta:
model = Profile
fields = '__all__'
Views.py:
from rest_framework import viewsets, permissions
from .models import Profile
from .serializers import ProfileSerializer
class ProfileViewSet(viewsets.ModelViewSet):
queryset = Profile.objects.all()
permission_classes = [
permissions.AllowAny
]
serializer_class = ProfileSerializer
The issue is that in the Api, the return values of the method aren't there. The friends_list method for example is supposed to return a list of friends you have and even though this does work in a traditional django project, the Django Rest Framework is not showing any value for this method. How can I fix this and get the return values for both methods to show up in the api?
Since the model serializer picks up only model fields for the serializer fields, you won't automatically get any methods copied over.
You can still send this read only data over the API by explicitly adding the two fields with reference to the model methods
class ProfileSerializer(serializers.ModelSerializer):
class Meta:
model = Profile
fields = [
# need to explicitly define all fields I believe
'friends_list',
'number_of_friends',
]
Now that the two fields (matching the method name are declared, DRF should create SerializerMethodField or ReadOnly field (not sure which one, but they are similar) for each of them.
It works coz it sets the source for those fields to be the same name, and if finds some attribute (in this case the methods) on the model.
If that doesn't work, you can
class ProfileSerializer(serializers.ModelSerializer):
friends_list = serializers.SerializerMethodField()
number_of_friends = serializers.SerializerMethodField()
class Meta:
model = Profile
fields = [
# need to explicitly define all fields I believe
'friends_list',
'number_of_friends',
]
def get_friends_list(self, instance):
return instance.friends_list()
def get_number_of_friends(self, instance):
return instance.number_of_friends()
when you use __all__ it call fields only you have to call fields with methods using list like that
`fileds = ["first_name","last_name","user",
"friends","friends_list","number_of_friends"
]`
Related
I want to be able to sort a table column defined using a custom method in the Django admin.
I narrowed down the problem to this simple example in Django:
models.py:
from django.db import models
class MyObject(models.Model):
name = models.CharField(_("name"), max_length=255)
layers = models.URLField(_("Layers"), blank=True, max_length=1024)
choices = models.TextField(
verbose_name=_("Choice values"),
blank=True,
help_text=_("Enter your choice"),
)
class Meta:
verbose_name = _("Object config")
verbose_name_plural = _("Objects config")
def __str__(self): # my custom method
return self.name
and admin.py:
from django import forms
from django.contrib import admin
class MyObjectAdminForm(forms.ModelForm):
"""Form"""
class Meta:
model = models.MyObject
fields = "__all__"
help_texts = {
"layers": "URL for the layers",
}
class MyObjectAdmin(admin.ModelAdmin):
form = MyObjectAdminForm
list_filter = ["name",]
search_fields = ["name",]
# I want the first column (__str__) to be sortable in the admin interface:
list_display = ["__str__", ...] # the ... represent some other DB fields
but for the moment I cannot sort that first column (it is grayed out, I cannot click on its title):
So how could I sort the first column in this admin table as defined by the __str__() method of the MyObject model? (please note that I cannot change the model itself. I'm also brand new to Django, so don't hesitate to detail your answer as if you were speaking to a kid.)
My models have users that can have multiple devices. When I do a GET request on users it returns only the fields specified in the user model, as it should. But I want the option to include in the JSON returned by the GET request the list of devices the user has. How can I do that? Secondly, is there a way I can sometimes get a user with the list of devices in the same JSON, and other times without it? Also, I am really new to Django, and I would appreciate a lot code examples to understand better, if possible.
These are my models:
class User(models.Model):
name = models.CharField(max_length=100)
birth_date = models.DateField()
address = models.CharField(max_length=200)
class Device(models.Model):
description = models.CharField(max_length=200)
location = models.CharField(max_length=200)
max_energy_consumption = models.FloatField()
avg_energy_consuumption = models.FloatField()
user = models.ForeignKey(User, on_delete=models.CASCADE, null=True)
My serializers:
class UserSerializer(serializers.ModelSerializer):
class Meta:
model = User
fields = '__all__'
class DeviceSerializer(serializers.ModelSerializer):
class Meta:
model = Device
fields = '__all__'
And the following default ModelViewSets for CRUD api calls:
class UserViewSet(ModelViewSet):
queryset = User.objects.all()
serializer_class = UserSerializer
class DeviceViewSet(ModelViewSet):
queryset = Device.objects.all()
serializer_class = DeviceSerializer
There are some different ways easiest one would be add a property in your User model and add that to your serializer
class User(models.Model):
name = models.CharField(max_length=100)
birth_date = models.DateField()
address = models.CharField(max_length=200)
#property
def devices(self):
return Device.objects.filter(user_id=self.id).values("location", "description").distinct()
class UserSerializer(serializers.ModelSerializer):
devices = serializers.ReadOnlyField()
class Meta:
model = User
fields = '__all__'
EDIT - for second part of your question:
I have experienced that writing '__all__' in our serializers not the best thing to do when we do not need all the information all the time(performance issues). To address this obsticle making a seperate serializer would be again an easy solution. Whenever I am facing this kind of thing i query same endpoint but send a different qs that i dont use in other endpoint in your case lets say your user viewsets route is something like /api/user/ you can add a qs when you send your get request to your backend and add ?with_devices=true.
Then you can use your second user serializer like this:
class UserViewSet(ModelViewSet):
queryset = User.objects.all()
def get_serializer_class(self):
if self.request.GET.get("with_devices", False):
return UserWithDeviceSerializer
return UserSerializer
where your serializers would be something like:
class UserSerializer(serializers.ModelSerializer):
class Meta:
model = User
fields = ["name", "birth_date", ..so on]
class UserWithDeviceSerializer(serializers.ModelSerializer):
devices = serializers.ReadOnlyField()
class Meta:
model = User
fields = '__all__'
This would give you what you asked in the comment.
I am trying to update my Teachers view in DRF by instead of including the link to the department field, I would display the name of the department. When I added the PrimaryKeyRelated field, I was able to see the department.name but couldnt use update or create within DRF. Is there a way I could change the display without causing the need for the methods or is that not the case?
Error
The `.update()` method does not support writable dotted-source fields by default.
Write an explicit `.update()` method for serializer `school.serializers.TeacherSerializer`, or set `read_only=True` on dotted-source serializer fields.
The `.create()` method does not support writable dotted-source fields by default.
Write an explicit `.create()` method for serializer `school.serializers.TeacherSerializer`, or set `read_only=True` on dotted-source serializer fields.
models.py
class Department(models.Model):
name = models.CharField(max_length=300)
def __str__(self):
return self.name
class Teacher(models.Model):
name = models.CharField(max_length=300)
department = models.ForeignKey(Department, on_delete=models.CASCADE)
tenure = models.BooleanField()
def __str__(self):
return f'{self.name} teaches {self.department}'
# dont need success url if get_absolute_url on create and update view
def get_absolute_url(self):
return reverse('teacher', kwargs={'pk': self.pk})
serializers.py
class TeacherSerializer(serializers.HyperlinkedModelSerializer):
department = serializers.PrimaryKeyRelatedField(
source='department.name', queryset=Department.objects.all())
class Meta:
model = Teacher
fields = ['url', 'name', 'department', 'tenure']
class DepartmentSerializer(serializers.HyperlinkedModelSerializer):
teacher_set = TeacherSerializer(many=True, required=False)
class Meta:
model = Department
fields = ['url', 'name', 'teacher_set']
views.py
class TeacherViewSet(viewsets.ModelViewSet):
queryset = Teacher.objects.all()
serializer_class = TeacherSerializer
permission_classes = [permissions.IsAuthenticatedOrReadOnly]
class DepartmentViewSet(viewsets.ModelViewSet):
queryset = Department.objects.all()
serializer_class = DepartmentSerializer
permission_classes = [permissions.IsAuthenticatedOrReadOnly]
have you tried add related_name for model Teacher in field foreign key and call in serializers? link to docs
I'm trying to link 'owner' field of my model to an AbstractUser. I need it to be done automatically, the only think i'm able to do by myself is to allow user logged in to choice between every existing user with, what's not what i want. I would like to not have a field to manipulate, but a outcome serializer with id or username of User that added the model. I'm trying to find solutions for a few days, I've tried already combine ForeignKey, PrimaryKeys, OneToOneField, HiddenField, get_user, perform_create, but I'm for sure doing something wrong, and i'm almost lost with it. The last thing i tried is to def_perform in views like DRF QuickStart tutorial say, but without results.
I add some code sample to be more understandable:
There is my AbstractUser model:
from django.db import models
from django.contrib.auth.models import AbstractUser
class UserProfile(AbstractUser):
username = models.CharField(max_length=20, unique=True)
...
i added it to AUTH_USER_MODEL = in the settings.
And there is other model which i want to link with User:
from django.db import models
from users.models.user import UserProfile
class MyPhoto(models.Model):
owner = models.ForeignKey(UserProfile, related_name='photos', on_delete=models.CASCADE, null=True)
image = models.ImageField(upload_to='Images')
serializer.py
class MyPhotoSerializer(serializers.ModelSerializer):
owner = serializers.ReadOnlyField(source='owner.username')
class Meta:
model = MyPhoto
fields = ('pk', 'image', 'owner')
def create(self, validated_data):
photo = MyPhoto.objects.create(
image=validated_data['image']
)
photo.save()
return photo
views.py
class UpdateMyPhotoViewSet(viewsets.ModelViewSet):
queryset = MyPhoto.objects.all()
serializer_class = MyPhotoSerializer
permission_classes = (IsAuthenticated,)
def perform_create(self, serializer):
serializer.save(created_by=self.request.user)
and for now i can't see the owner field results.
Thanks in advance.
I have been getting my head around these basics but I am not getting it right. I am trying to associate my view to my user model using team which is a foreign key. When I try to create of a gps, I get an error saying "team is a required field" but instead it should be read only. The team attribute should be filled automatically with the id of the currentUser
Model
class User(models.Model):
first_name = models.CharField(max_length=200,blank=False)
last_name = models.CharField(max_length=200, blank=False)
class Gps(models.Model):
location = models.CharField(max_length=200,blank=False)
team= models.ForeignKey(User, on_delete=models.CASCADE)
serializers
class GpsSerializer(serializers.ModelSerializer):
class Meta:
model = Gps
fields = ('id','location','team')
view
class Gps_list(generics.ListCreateAPIView):
queryset = Gps.objects.all()
serializer_class = GpsSerializer
team = serializers.PrimaryKeyRelatedField(
read_only=True,
default=serializers.CurrentUserDefault()
)
There are two changes needed. First, team field definition should be moved to serializer class instead of view. Second, you should use Django's contrib.auth.User model instead of your definition of User, as because serializers.CurrentUserDefault() will bring request.user only. So you should remove your User definition and import that to your models.py:
from django.contrib.auth.models import User
Further steps would be to replace read_only=True with queryset=User.objects.all() to allow create.