I might not get understand the concept of serializers right but as I think, serializers are used to represent python objects as json objects.
So my question is, I've got a model:
class User(AbstractUser):
messages = models.IntegerField(default=0)
signup_date = models.DateField(auto_now_add=True)
last_msg = models.DateField(null=True, blank=True)
and a serializer:
class UserSerializer(serializers.ModelSerializer):
password = serializers.CharField(write_only=True)
class Meta:
model = User
fields = ['username', 'password', 'email']
As my API View returns json, I want to pass a serialized username but I don't know how to achieve it.
This is a piece of code written without serializers so I'm trying to get the same result using them:
chat_session = ChatSession.objects.get(uri=uri)
owner = chat_session.owner
if owner != user: # Only allow non owners join the room
chat_session.members.get_or_create(
user=user, chat_session=chat_session
)
owner = deserialize_user(owner)
members = [
deserialize_user(chat_session.user)
for chat_session in chat_session.members.all()
]
How can I access my Serializer for a specific user instead of using a custom deserialize_user function
I believe
members = UserSerializer(many=True).to_representation(chat_session.members.all())
would do the trick.
Related
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've been scratching my head about this problem for a couple of hours now. Basically, I have two models: User and Project:
class User(AbstractUser):
username = None
email = models.EmailField("Email Address", unique=True)
avatar = models.ImageField(upload_to="avatars", default="avatars/no_avatar.png")
first_name = models.CharField("First name", max_length=50)
last_name = models.CharField("Last name", max_length=50)
objects = UserManager()
USERNAME_FIELD = "email"
class Project(models.Model):
name = models.CharField("Name", max_length=8, unique=True)
status = models.CharField(
"Status",
max_length=1,
choices=[("O", "Open"), ("C", "Closed")],
default="O",
)
description = models.CharField("Description", max_length=3000, default="")
owner = models.ForeignKey(
User, on_delete=models.SET_NULL, null=True, related_name="project_owner"
)
participants = models.ManyToManyField(User, related_name="project_participants", blank=True)
created_at = models.DateTimeField(auto_now_add=True)
I use standard ModelViewSets for both of them, nothing changed. Then there's my Project serializer:
class ProjectSerializer(serializers.ModelSerializer):
class Meta:
model = Project
fields = "__all__"
status = serializers.CharField(source="get_status_display", required=False)
owner = UserSerializer()
participants = UserSerializer(many=True)
I use UserSerializers here, because having them achieved first of my two goals:
I wanted to get the user data when getting the project from the API -> owner is a serialized User with all the fields, same for participants, but it's a list of users
I want to be able to partially update the Project, for example add a participant
So I searched through the docs and SO and I always found answers that answer one of those questions, but never both of them.
The thing with my second goal is: when I do the partial update (via PATCH, of course), I get the response that: "Invalid data. Expected a dictionary, but got int." when I pass a list of ints (user ids) for the participants. I thought: okay, maybe I have to pass the whole user data to change it. But then I realised: when I remove the UserSerializer from ProjectSerializer - passing just the list of ints in Postman works just fine. And that is a life saver, cuz who wants to create a request with a whole bunch of data, when I can just pass user ids.
But then of course when I remove the UserSerializer, when I call get project, I get participants: [1,2,3,4,...], not participants: [{"id": 1, "name": "John", ...}, ...}]. And I really want this behavior, because I don't want to make additional API calls just to get the users' data by their IDs.
So summing up my question is: Is there a way to leave those serializers in place but still be able to partially update my model without having to pass whole serialized data to the API (dicts instead of IDs)? Frankly, I don't care about the serializers, so maybe the question is this: Can I somehow make it possible to partially update my Products' related fields like owner or participants just by passing the related entities IDs while still maintaining an ability to get my projects with those fields expanded (serialized entities - dicts, instead of just IDs)?
#Edit:
My view:
from rest_framework import viewsets, permissions
from projects.models import Project
from projects.api.serializers import ProjectSerializer
class ProjectViewSet(viewsets.ModelViewSet):
queryset = Project.objects.all()
serializer_class = ProjectSerializer
permission_classes = [permissions.IsAuthenticated]
lookup_field = "name"
def get_queryset(self):
if self.request.user.is_superuser:
return Project.objects.all()
else:
return Project.objects.filter(owner=self.request.user.id)
def perform_create(self, serializer):
serializer.save(owner=self.request.user, participants=[self.request.user])
Answer:
To anyone reading this, I've solved this problem and I actually created a base class for all my viewsets that I want this behavior to be in:
from rest_framework.response import Response
class ReadWriteViewset:
write_serializer_class = None
read_serializer_class = None
def update(self, request, *args, **kwargs):
partial = kwargs.pop("partial", False)
instance = self.get_object()
write_serializer = self.write_serializer_class(
instance=instance,
data=request.data,
partial=partial,
)
write_serializer.is_valid(raise_exception=True)
self.perform_update(write_serializer)
read_serializer = self.read_serializer_class(instance)
if getattr(instance, "_prefetched_objects_cache", None):
# If 'prefetch_related' has been applied to a queryset, we need to
# forcibly invalidate the prefetch cache on the instance.
instance._prefetched_objects_cache = {}
return Response(read_serializer.data)
Then you use it kinda like in here
I'm assuming that you are using a ModelViewSet. You could use different serializers for different methods.
class ProjectViewSet(viewsets.ModelViewSet):
def get_serializer_class(self):
if self.action in ['create', 'update']:
return WriteProjectSerializer # your serializer not using `UserSerializer` that works for updating
return ProjectSerializer # your default serializer with all data
Edit for using different serializers in same method:
# you can override `update` and use a different serializer in the response. The rest of the code is basically the default behavior
def update(self, request, *args, **kwargs):
partial = kwargs.pop('partial', False)
instance = self.get_object()
write_serializer = WriteProjectSerializer(data=request.data)
serializer.is_valid(raise_exception=True)
instance = self.perform_update(serializer)
read_serializer = ProjectSerializer(instance)
if getattr(instance, '_prefetched_objects_cache', None):
# If 'prefetch_related' has been applied to a queryset, we need to
# forcibly invalidate the prefetch cache on the instance.
instance._prefetched_objects_cache = {}
return Response(read_serializer.data)
A good way to see the default code for all these methods is using Classy DRF. You can see all methods that come with using ModelViewSet and use that code with some changes. Here I'm using the default code for update but changing for a new serializer for the response.
Hi there Im trying to retrieve a specific object from the related model so as to render data to my view specific to that particular object, in my case I have a custom user model and a related model called Seller.
Models
from django.db import models
from django.contrib.auth.models import AbstractUser
# Create your models here.
class CustomUser(AbstractUser):
is_customer = models.BooleanField(default=False)
is_seller = models.BooleanField(default=False)
class Seller(models.Model):
user = models.ForeignKey(CustomUser, on_delete=models.CASCADE, blank=True, null=True)
store_name = models.CharField(max_length=120)
address = models.CharField(max_length=180)
phone = models.IntegerField(blank=True, null=True)
email = models.CharField( max_length=180, blank=True, null=True )
def __str__(self):
return self.store_name
View
#method_decorator( seller_required , name='dispatch')
class SellerDashBoardView(ListView):
model = Seller
template_name = 'seller_dashboard.html'
def get_context_data(self, *args, **kwargs):
user = CustomUser.seller_set.filter(store_name=self.request.user.username)
context = super(SellerDashBoardView, self).get_context_data( **kwargs)
context['products'] = Product.objects.filter(seller=user)[:6]
return context
This is because when you want to filter ManyToOne reverse Relation, you have to make exact the same query as you would've been done with a direct relation:
CustomUser.objects.filter(seller__store_name="Whole Foods")
# Note that would return a queryset not a single user!
# If you want a CustomUser object you will have to use either get or index the query
The doc example and explanations are provided here:
https://docs.djangoproject.com/en/3.1/topics/db/examples/many_to_one/
It is also better to use prefetch_related method to tell djano ORM that it does not have to make as many queries as number of related objects, that query should be done in 2 database queries instead of lenght of your related query:
CustomUser.objects.prefetch_related("seller_set").filter(seller__store_name="Whole Foods")
The doc link:
https://docs.djangoproject.com/en/3.1/ref/models/querysets/#prefetch-related
You probably would like to use ...seller_set.filter when you already got a CustomUser object. So if you want to filter its sellers you would use that:
...
user.seller_set.filter(store_name="Whole Foods")
That would provide you the Seller objects queryset filtered by a store name related to a specific user. Basically the same query as this:
Seller.objects.filter(user_pk=user.pk, store_name="Whole Foods")
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.
I am very new to Python and Django. I am trying to setup user model for different roles like Agents, Brokers, Company and Customer. Each of these roles can register with the site as a user. Then Agents and Brokers can have public facing profile pages.
Do I have to use custom user model or built in user model will work? I have additional properties like license, location, languages, photo etc for Agents and Brokers.
class MyUser(AbstractBaseUser):
AGENTS = 'AG'
BROKERS = 'BR'
COMPANY = 'CP'
CUSTOMER = 'CM'
ROLE_IN_CHOICES = (
(AGENTS, 'Agent'),
(BROKERS, 'Broker'),
(COMPANY, 'Company'),
(CUSTOMER, 'Customer'))
first_name = models.CharField(max_length=100, blank=True)
second_name = models.CharField(max_length=100, blank=True)
middle_name = models.CharField(max_length=100, blank=True)
dob = models.DateField(blank=True, null=True)
phone = models.CharField(max_length=10)
secondary_phone = models.CharField(max_length=10, blank=True, null=True)
......
#property
def is_agent(self):
return self.role in (self.AGENTS)
#property
def is_customer(self):
return self.role in (self.CUSTOMER)
#property
def is_broker(self):*
return self.role in (self.BROKER)
#property
def is_company(self):
return self.role in (self.COMPANY)
....
Can I not use base User model and achieve same? Am I on write track?
How do I create public facing pages for these roles (Agents, Brokers)?
This is my first attempt with Python and Django. I am using Django 1.7.7 with Python 3.4
You should extend from the Django User model instead and add the extra fields you need:
from django.contrib.auth.models import User as Auth_User
class User(Auth_User):
# add your extra fields here like roles, etc
phone = CharField(max_length=20, null=True, blank=True)
# add your extra functions
def extra_user_function(self):
return "This is an extra function"
This way you have your own fields and also the Django User fields...
After migrating, if you check the database, you'll have auth_user and your_app_user tables.
Just bare in mind that request.user will only give you the super fields... In order to get the extended class you'll need
User.objects.get(id=request.user.id)
The latest will only have the extra fields and its id will be the same as the auth.User if you don't add any auth_user by itself.
Attention: this is important!
Otherwise request.user.id and your_app.User.id don't match, therefore User.objects.get(id=request.user.id) won't work and you'll have to query the db to find the your_app.User.id
User.object.get(user_ptr_id = request.user.id)
Other things to consider
This will work:
# you_app.User objects gets vars from auth.User
user = User.objects.get(id=request.user.id)
first_name = user.first_name
But this won't work
# auth.User trying to get a function from your_app.User
user = request.user
user.extra_user_function()
So the User model could be something like this:
import os
from django.contrib.auth.models import User as Django_User
from django.db.models import CharField, ImageField
class User(Django_User):
phone = CharField(max_length=20, null=True, blank=True)
observations = CharField(max_length=2048, null=True, blank=True)
picture = ImageField(upload_to='users', default='default/avatar.jpg')
class Meta:
# adding extra permissions (default are: add_user, change_user, delete_user)
permissions = (
("access_user_list", "Can access user list"),
("access_user", "Can access user"),
)
ordering = ["-is_staff", "first_name"]
Instead of creating roles on the user, Django already has groups, so you should use them.
The groups follow the same logic:
from django.contrib.auth.models import Group as Auth_Group
from django.db import models
class Group(Auth_Group):
observations = models.CharField(max_length=2048, null=True, blank=True)
def get_users_in_group(self):
return self.user_set.filter(is_active=1).order_by('first_name', 'last_name')
def count_users_in_group(self):
return self.user_set.count()
def __unicode__(self):
return self.name
class Meta:
permissions = (
("access_group_list", "Can access group list"),
("access_group", "Can access group"),
)
ordering = ["name"]
You can clear / add users to a group:
user.groups.clear()
user.groups.add(group)
Clear / add permissions to the group:
group.permissions.clear()
group.permissions.add(permission)
There is also a decorator to check if a user has permissions
from django.contrib.auth.decorators import permission_required
#permission_required(("users.change_user","users.access_user",))
def your_view(request):
...
I've tried many things in the past, but I guess this is the way to go.
If you really need roles, and a user can have more than one role, mayb the best thing would be to create a model Role and add that to the user has a ManyToMany Field
roles = ManyToManyField(Role)
but you could do that with groups