I have models (one user can has multiple employees):
from django.db import models
class User(models.Model):
username = ...
first_name = ...
last_name = ...
class OrgUnit(models.Model):
name = ....
address = ...
class Employee(models.Model):
personnel_no = ...
user = models.ForeignKey(User, related_name='employees'...)
orgunit = models.ForeignKey(OrgUnit, ...)
Serializers and views:
class EmployeeSerializer(serializers.ModelSerializer):
orgunit = serializers.CharField(source='orgunit.name') <==== one orgunit - one query to DB
class Meta:
model = Employee
fields = '__all__'
class CustomUserSerializer(serializers.ModelSerializer):
employees = EmployeeSerializer(many=True)
class Meta:
model = User
fields = '__all__'
class UsersViewSet(ViewSet):
def me(self, request):
serializer = CustomUserSerializer(request.user)
return Response(serializer.data)
When serializing orgunit.name per one orgunit one query to DB is being performed. How to avoid this? How to prefetch employees related_name and its orgunits?
In this case you can use Prefetch..[Django-doc] and prefetch_related_objects..[Django-doc] to fetch all related employees with orgunit selected as well:
from django.db.models import Prefetch, prefetch_related_objects
class UsersViewSet(ViewSet):
def me(self, request):
prefetch_related_objects(
[request.user],
Prefetch(
"employees",
queryset=Employee.objects.select_related("orgunit"),
),
)
serializer = CustomUserSerializer(request.user)
return Response(serializer.data)
Related
Working on a django project I am a bit stuck on data representation through APIs. In fact when designing models the data model is quite stratighforward : I have a one to many relationship A--> B
therefore I have added a FK to object B.
Object B has a boolean attribute "active".
I would like to make an API call to list all A objects having at least one assoicated object B with active = true.
The api could be like this :
/api/objectA/?ObjectB.active=True
Here is my code :
Models :
from django.contrib.postgres.fields import ArrayField
from django.core.exceptions import ValidationError
from django.db import models
from django.db.models.signals import pre_save
from django.dispatch import receiver
class Startup(models.Model):
header = models.CharField("Header", max_length=255)
title = models.CharField("Title", max_length=255)
description = models.CharField("description", max_length=255)
# TODO Change this to options instead of array
tags = ArrayField(models.CharField(max_length=10, blank=True), size=5)
# TODO Images to be stored in aws only url will be in DB
card_image = models.ImageField(upload_to='media/images/cards')
logo_image = models.ImageField(upload_to='media/images/logos')
main_img = models.ImageField(upload_to='media/images/main', null=True)
createdAt = models.DateTimeField("Created At", auto_now_add=True)
def __str__(self):
return self.title
class Investment(models.Model):
# TODO change the name of Investment to fund round in back and front
# TODO all price to be checked for max digits and decimal places
startup = models.ForeignKey(Startup, related_name='startup_investments', on_delete=models.CASCADE, default="1")
# Use the related_name as a serializer bale for investments inside startup serializer
Investment_title = models.CharField("Investment_title", max_length=255, default="Missing Title")
collected_amount = models.DecimalField(max_digits=12, decimal_places=2)
goal_percentage = models.IntegerField(default=0)
number_of_investors = models.IntegerField(default=0)
days_left = models.IntegerField()
active = models.BooleanField(default=False)
# TODO Need to update this to prevent linking to a non existing startup
createdAt = models.DateTimeField("Created At", auto_now_add=True)
def clean(self):
"""Validate that the startup does not have already an active Investment """
if self.active:
qs = Investment.objects.filter(active=True).filter(startup=self.startup)
if self.pk is not None:
qs = qs.exclude(pk=self.pk)
if qs:
raise ValidationError(message="An active investment already exists for this startup")
def __str__(self):
return self.Investment_title
Serializers :
from rest_framework import serializers
from .models import Startup, Investment
class InvestmentSerializer(serializers.ModelSerializer):
class Meta:
model = Investment
fields = ('id', 'Investment_title', 'collected_amount', 'goal_percentage', 'number_of_investors',
'days_left', 'active')
class StartupSerializer(serializers.ModelSerializer):
startup_investments = InvestmentSerializer(many=True, read_only=True)
class Meta:
model = Startup
fields = ('id', 'header', 'title', 'description', 'tags', 'card_image',
'logo_image', 'main_img', 'startup_investments')
Views :
from django_filters import rest_framework as filters
from rest_framework.viewsets import ModelViewSet
from rest_framework_extensions.mixins import NestedViewSetMixin
from .serializers import *
class StartUpViewSet(NestedViewSetMixin, ModelViewSet):
"""
Class that provides List, Retrieve, Create, Update, Partial Update and Destroy actions for startups.
It also include a filter by startup status
"""
model = Startup
queryset = Startup.objects.all()
serializer_class = StartupSerializer
class InvestmentViewSet(NestedViewSetMixin, ModelViewSet):
"""
Class that provides List, Retrieve, Create, Update, Partial Update and Destroy actions for Investments.
It also include a active and investment title
"""
model = Investment
serializer_class = InvestmentSerializer
queryset = Investment.objects.all()
filter_backends = (filters.DjangoFilterBackend,)
filterset_fields = ('active', 'Investment_title')
routers :
router = ExtendedSimpleRouter()
(
router.register(r'api/investments', views.InvestmentViewSet, basename='investment'),
router.register(r'api/startups', views.StartUpViewSet, basename='startup')
.register(r'investments', views.InvestmentViewSet, basename='startups_investment',
parents_query_lookups=['startup']),
)
Thanks for your help.
I would try something like this:
class StartUpViewSet(NestedViewSetMixin, ModelViewSet):
model = Startup
#queryset = Startup.objects.all()
serializer_class = StartupSerializer
def get_queryset(self):
Startup.objects.annotate(active_investments=Count('startup_investments', filter=Q(startup_investments__active=True)).filter(active_investments__gt=0)
Hello I am posting this answer hoping it will help others as I have spent two days to make this work!!
class ActiveStartupSerializer(serializers.ListSerializer):
def to_representation(self, data):
"""List all startups with one active investment"""
data = data.filter(startup_investments__active=True)
return super(ActiveStartupSerializer, self).to_representation(data)
class Meta:
model = Startup
fields = ('id', 'header', 'title', 'description', 'tags', 'card_image',
'logo_image', 'main_img', 'startup_investments')
class InvestmentSerializer(serializers.ModelSerializer):
class Meta:
model = Investment
fields = ('id', 'Investment_title', 'collected_amount', 'goal_percentage', 'number_of_investors',
'days_left', 'active')
class StartupSerializer(serializers.ModelSerializer):
startup_investments = InvestmentSerializer(many=True, read_only=True)
class Meta:
model = Startup
list_serializer_class = ActiveStartupSerializer
fields = ('id', 'header', 'title', 'description', 'tags', 'card_image',
'logo_image', 'main_img', 'startup_investments')
This is my models.py
class InvoiceLine(AbstractSaleLine):
invoice = models.ForeignKey('books.Invoice',
related_name="lines")
name = models.ForeignKey('books.Item')
tax_rate = models.ForeignKey('books.TaxRate')
class Meta:
pass
class Item(models.Model):
item = models.CharField(max_length=255)
created_by = models.ForeignKey(User, on_delete=models.CASCADE, related_name="Item", default=1)
views.py
class InvoiceCreateView(generic.CreateView):
template_name = "books/invoice_create_or_update.html"
model = Invoice
form_class = InvoiceForm
formset_class = InvoiceLineFormSet
success_url = reverse_lazy("books:invoice-list")
forms.py
class InvoiceLineForm(RestrictLineFormToOrganizationMixin,
ModelForm):
class Meta:
model = InvoiceLine
fields = (
"name",
"tax_rate",
"item_id"
)
How do i filter Item the foreign key by field created_by using CBV? I am using CreateView.
You can override get_queryset, to get current user use self.request.user. To filter by related model's field use __ notation:
class InvoiceCreateView(generic.CreateView):
template_name = "books/invoice_create_or_update.html"
model = InvoiceLine
form_class = InvoiceForm
formset_class = InvoiceLineFormSet
success_url = reverse_lazy("books:invoice-list")
def get_queryset(self):
return InvoiceLine.objects.filter(name__created_by=self.request.user)
You can override the queryset for the ModelChoiceField when the form is initialised:
class InvoiceLineForm(RestrictLineFormToOrganizationMixin, ModelForm):
def __init__(self, *args, **kwargs):
user = kwargs.pop('user')
self.fields['item'].queryset = Item.objects.filter(created_by=user)
class Meta:
model = InvoiceLine
fields = (
"name",
"tax_rate",
"item" # Note this should be `item` not `item_id`
)
You then need to pass the user to the form when you initialise the formset - something like:
formset = formset_class(form_kwargs={'user': self.request.user})
I have a customer model in Bcustomer app that extends the django User model, So I will save the basic details such as name in User table and the remaining data (city, etc) in customer table.
Saving is working perfectly. But now it is showing the following error when I call the GET method.
AttributeError at /api/v1/customer 'str' object has no attribute 'values'
Request Method: GET
bcustomer/models.py
class BCustomer(models.Model):
customer = models.OneToOneField(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, primary_key=True, blank=True )
address = models.CharField(max_length=50)
city = models.CharField(max_length=256)
state = models.CharField(max_length=50)
user = models.ForeignKey(settings.AUTH_USER_MODEL, db_index=True, on_delete=models.CASCADE, related_name='customer_creator')
# more fields to go
def __str__(self):
# return str(self.name) (This should print first and last name in User model)
class Meta:
app_label = 'bcustomer'
bcusomer/serializers.py
class CustomerDetailsSerializer(serializers.ModelSerializer):
class Meta:
model = BCustomer
fields = ('city', 'phone')
class CustomerSerializer(serializers.ModelSerializer):
customer_details = CustomerDetailsSerializer()
class Meta:
model = get_user_model()
fields = ('id','first_name', 'email', 'customer_details')
def create(self, validated_data):
request = self.context.get('request')
customer_details_data = validated_data.pop('customer_details')
customer_user = get_user_model().objects.create(**validated_data)
BCustomer.objects.create(customer=customer_user, user=request.user, **customer_details_data)
customer_user.customer_details = customer_details_data
return customer_user
class CustomerListSerializer(serializers.ModelSerializer):
model = get_user_model()
fields = '__all__'
class Meta:
model = get_user_model()
fields = '__all__'
bcustomer/views.py
class CustomerViewSet(viewsets.ModelViewSet):
customer_photo_thumb = BCustomer.get_thumbnail_url
permission_classes = [permissions.IsAuthenticated, TokenHasReadWriteScope]
queryset = BCustomer.objects.all()
serializer_class = CustomerSerializer
def get_queryset(self):
queryset = BCustomer.objects.all()
return queryset
def get_serializer_class(self):
if self.action == 'list' or self.action == 'retrieve':
return CustomerListSerializer
return CustomerSerializer
bcustomer/urls.py
router.register(r'customer', views.CustomerViewSet, 'customers')
Data post parameter format
{
"first_name":"Myname",
"email":"testemail#gmail.com",
"customer_details": {
"city":"citys",
"phone":"04722874567",
}
}
You should remove model and fields from CustomListSerializer
class CustomerListSerializer(serializers.ModelSerializer):
class Meta:
model = get_user_model()
fields = '__all__'
customer_details = CustomerDetailsSerializer()
You need to set the source argument to point to the user model's customer. Most probably:
customer_details = CustomerDetailsSerializer(source='customer')
(or maybe source='bcustomer', not sure if it reversed the field name or class name).
On a side not, you should not need the ListSerializer at all. The list method will call the serializer with the many=True argument on CustomerSerializer which will create the ListSerializer appropriately.
In my model, I have two tables named: Vtable and Vdata. Each virtual table (in Vtable) has entries of virtual data stored in Vdata.
I'm trying to make a view that would show the list of Vdata corresponding to each Vtable
My serializer isn't working and I think it's because I'm doing it backwards.
I think the problem is in this line:
table_id = serializers.RelatedField(many=True)
For reference, I get this error: 'Vtable' object is not iterable
Here is my models.py:
from django.db import models
from django.contrib.auth.models import User
class Vtable(models.Model):
user = models.ForeignKey(User)
table_name = models.CharField(max_length=200)
added_date = models.DateTimeField('date added')
def __unicode__(self):
return self.table_name
class Vdata(models.Model):
table_id = models.ForeignKey(Vtable)
table_pk = models.IntegerField()
column_1 = models.CharField(max_length=200)
column_2 = models.CharField(max_length=200)
added_date = models.DateTimeField('date added')
def __unicode__(self):
return str(self.added_date)
Here is my serializers.py:
from django.contrib.auth.models import User, Group
from rest_framework import serializers
from vtables.models import Vtable, Vdata
class TableSerializer(serializers.HyperlinkedModelSerializer):
user = serializers.Field(source='user.username')
class Meta:
model = Vtable
fields = ('table_name', 'added_date', 'user')
class EntrySerializer(serializers.HyperlinkedModelSerializer):
table_id = serializers.RelatedField(many=True)
class Meta:
model = Vdata
fields = ('table_id', 'table_pk', 'column_1', 'column_2', 'added_date')
Here is the view that calls it:
class EntryList(APIView):
def get(self, request, format=None):
entries = Vdata.objects.all()
serializer = EntrySerializer(entries, many=True)
return Response(serializer.data
class Meta:
model = Vdata
fields = ('table_id', 'table_pk', 'column_1', 'column_2', 'added_date')
Here is an example of how you might do this:
class TableSerializer(serializers.HyperlinkedModelSerializer):
user = serializers.Field(source='user.username')
entries = EntrySerializer(many=True)
class Meta:
model = Vtable
fields = ('table_name', 'added_date', 'user', 'entries')
class EntrySerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Vdata
fields = ('table_id', 'table_pk', 'column_1', 'column_2', 'added_date')
And for the view:
class EntryList(GenericAPIView):
queryset = Vtable.objects.all()
serializer_class = TableSerializer
Do not forget about:
setting related_name='entries' in your model foreign key field definition.
How to limit images of request.user to be linked with node. I wish I could do something like:
photo = models.ForeignKey(
Image,
limit_choices_to={'owner': username},
)
but request.user rather than username and I don't want to use local threads.
models.py
class Node(models.Model):
owner = models.ForeignKey(User)
content = models.TextField()
photo = models.ForeignKey(Image)
class Image(models.Model):
owner = models.ForeignKey(User)
file = models.ImageField(upload_to=get_upload_file_name)
serializers.py
class ImageSerializer(serializers.ModelSerializer):
owner = serializers.Field('owner.username')
class Meta:
model = Image
fields = ('file', 'owner')
class NodeSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Node
fields = ('content', 'photo', 'owner')
I would deal with this by overriding get_serializer_class to dynamically return a serializer class at runtime, setting the choices option on the field there:
def get_serializer_class(self, ...):
user = self.request.user
owner_choices = ... # However you want to restrict the choices
class ImageSerializer(serializers.ModelSerializer):
owner = serializers.Field('owner.username', choices=owner_choices)
class Meta:
model = Image
fields = ('file', 'owner')
return ImageSerializer
You can create a custom foreign key field and define get_queryset() method there to filter related objects to only those of your user. The current user can be retrieved from the request in the context:
class UserPhotoForeignKey(serializers.PrimaryKeyRelatedField):
def get_queryset(self):
return Image.objects.filter(owner=self.context['request'].user)
class NodeSerializer(serializers.HyperlinkedModelSerializer):
photo = UserPhotoForeignKey()
class Meta:
model = Node
fields = ('content', 'photo', 'owner')
This example is using Django REST Framework version 3.
class CustomForeignKey(serializers.PrimaryKeyRelatedField):
def get_queryset(self):
return Table.objects.filter(is_active=True)
class Serializer(serializers.ModelSerializer):
(...)
table= CustomForeignKey()
class Meta:
(...)
even more easy is :
class Serializer(serializers.ModelSerializer):
(...)
table = serializers.PrimaryKeyRelatedField(queryset=Table.objects.filter(is_active=True))
class Meta:
(...)
Because I am sure this logic will be used across an entire Django application why not make it more generic?
class YourPrimaryKeyRelatedField(serializers.PrimaryKeyRelatedField):
def __init__(self, **kwargs):
self.model = kwargs.pop('model')
assert hasattr(self.model, 'owner')
super().__init__(**kwargs)
def get_queryset(self):
return self.model.objects.filter(owner=self.context['request'].user)
serializers.py
class SomeModelSerializersWithABunchOfOwners(serializers.ModelSerializer):
photo = YourPrimaryKeyRelatedField(model=Photo)
categories = YourPrimaryKeyRelatedField(model=Category,
many=True)
# ...
from rest_framework import serializers
class CustomForeignKey(serializers.PrimaryKeyRelatedField):
def get_queryset(self):
return Table.objects.filter(user=self.context['request'].user)
# or: ...objects.filter(user=serializers.CurrentUserDefault()(self))
class Serializer(serializers.ModelSerializer):
table = CustomForeignKey()