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Django Rest Framework: Use URL parameter in serializer

My goal is to use a URL parameter as a variable in a function and output it in the serializer. But the following solution doesnt work. Anybody know why?
The URL looks like this:
http://127.0.0.1:8000/v1/water-bodies/?from=2013-02-17&to=2013-02-18
models.py
class Application(models.Model):
"""Database models for application information"""
name = models.CharField(max_length=255)
machine_name = models.SlugField(max_length=255, allow_unicode=True)
description = models.TextField(blank=True, null=True)
indice_to_use = models.ForeignKey('Indice', on_delete=models.PROTECT, blank=True, null=True)
def __str__(self):
return self.name
views.py
class DetailView(APIView):
def get_serializer_context(self):
context = super().get_serializer_context()
context["date_from"] = self.request.query_params.get("from", None)
return context
def get(self, request, machine_name):
application = Application.objects.get(machine_name=machine_name)
serializer = OsdSerializer(application)
return Response({"Everything you need to analyzing "+application.name: serializer.data})
serializer.py
class OsdSerializer(serializers.ModelSerializer):
bands = BandSerializer(source='indice_to_use.needed_bands', many=True)
satellite = SatelliteSerializer(source='indice_to_use.satellite_to_use')
indice = IndiceSerializer(source='indice_to_use')
def get_alternate_name(self, obj):
return self.context.get('date_from')
class Meta:
model = Application
fields = ['machine_name', 'name', 'description', 'indice', 'satellite', 'bands', 'date_from', ]

We would be required to update the code at two places.
DetailView in views.py.
In this, we are updating context to include data_from. (please note, we can also access this directly in the serialzier)
class DetailView(APIView):
...
def get(self, request, machine_name):
application = Application.objects.get(machine_name=machine_name)
serializer = OsdSerializer(application, context={
"date_from": request.query_params.get("from")
})
return Response({"Everything you need to analyzing "+application.name: serializer.data})
...
OsdSerializer in the serializers.py
class OsdSerializer(serializers.ModelSerializer):
bands = BandSerializer(source='indice_to_use.needed_bands', many=True)
satellite = SatelliteSerializer(source='indice_to_use.satellite_to_use')
indice = IndiceSerializer(source='indice_to_use')
alternate_name = serializers.SerializerMethodField()
def get_alternate_name(self, obj):
return self.context.get('date_from')
class Meta:
model = Application
fields = ['machine_name', 'name', 'description', 'indice', 'satellite', 'bands', 'date_from', 'alternate_name']
Another approach would be to access the request object directly from the context of the serializer. By default, the serializer context contains the request object in it. To do so, just update the serializer as mentioned below
OsdSerializer in the serializers.py
class OsdSerializer(serializers.ModelSerializer):
bands = BandSerializer(source='indice_to_use.needed_bands', many=True)
satellite = SatelliteSerializer(source='indice_to_use.satellite_to_use')
indice = IndiceSerializer(source='indice_to_use')
alternate_name = serializers.SerializerMethodField()
def get_alternate_name(self, obj):
return self.context.get('request').query_params.get('from', None)
class Meta:
model = Application
fields = ['machine_name', 'name', 'description', 'indice', 'satellite', 'bands', 'date_from', 'alternate_name']

First you need to change from accessing the parameter from kwargs to request.GET instead.
If you have a url like this in django '/user/<int:user_id>' then you access through kwargs.
But if you send a url parameter, like this '/user/?user_id=1'. You access through the request object.
In your situation, I think rest_framework will send the request to the serializer automatically. So you can do something like this:
def get_alternate_name(self, obj):
date_from = self.request.GET.get('from')

date=self.context.get('request').parser_context.get('kwargs').get(
'edate')

Django rest framework, update object after creation

I have a DRF API that takes in the following model:
class Points(models.Model):
mission_name = models.CharField(name='MissionName',
unique=True,
max_length=255,
blank=False,
help_text="Enter the mission's name"
)
# Some irrlevant feid
url = models.URLField(help_text='Leave Empty!', default=" ")
date_added = models.DateTimeField(default=timezone.now)
class Meta:
get_latest_by = 'date_added'
And it's serializer:
from rest_framework.serializers import HyperlinkedModelSerializer
from .models import Points
class PointsSerializer(HyperlinkedModelSerializer):
class Meta:
model = Points
fields = (
'id', 'MissionName', 'GDT1Latitude', 'GDT1Longitude',
'UavLatitude', 'UavLongitude', 'UavElevation', 'Area',
'url', 'date_added'
)
And the view:
class PointsViewSet(ModelViewSet):
# Return all order by id, reversed.
queryset = Points.objects.all().order_by('-id')
serializer_class = PointsSerializer
data = queryset[0]
serialized_data = PointsSerializer(data, many=False)
points = list(serialized_data.data.values())
def retrieve(self, request, *args, **kwargs):
print(self.data)
mission_name = self.points[1]
assign_gdt = GeoPoint(lat=self.points[2], long=self.points[3])
gdt1 = [assign_gdt.get_lat(), assign_gdt.get_long()]
assign_uav = GeoPoint(lat=self.points[4], long=self.points[5], elevation=self.points[6])
uav = [assign_uav.get_lat(), assign_uav.get_long(), assign_uav.get_elevation()]
area_name = f"'{self.points[-2]}'"
main = MainApp.run(gdt1=gdt1, uav=uav, mission_name=mission_name, area=area_name)
print('file created')
return render(request, main)
I want to update the URL field of the file to contain a constant pattern and format in the end the mission_name field.
object.url = f'127.0.0.1/twosecondgdt/{mission_name}'
How can that be achieved and where should I store such code, the views.py or serializers.py?

There are several ways this could be achieved based on your requirements.
If you want to set the url upon creation even if it is not through the api, you can do it in the save method of the model itself:
class Points(models.Model):
# fields here
def save(self, **args, **kwargs):
if not self.url.strip():
# You may want to store the value of `127...` in an environment variable
self.url = f"127.0.0.1/twosecondgdt/{self.mission_name}"
super().save(*args, **kwargs)
If you want to set it through the view/serializer, you can set it in the create method of your serializer:
class PointsSerializer(HyperlinkedModelSerializer):
def create(self, validated_data):
mission_name = validated_data["mission_name"]
validated_data["url"] = f"127.0.0.1/twosecondgdt/{mission_name}"
return super().create(validated_data)
You can also override some methods in your viewset like perform_create or create

DRF: how to change the value of the model fields before saving to the database

If I need to change some field values before saving to the database as I think models method clear() is suitable. But I can't call him despite all my efforts.
For example fields email I need set to lowercase and fields nda I need set as null
models.py
class Vendors(models.Model):
nda = models.DateField(blank=True, null=True)
parent = models.OneToOneField('Vendors', models.DO_NOTHING, blank=True, null=True)
def clean(self):
if self.nda == "":
self.nda = None
class VendorContacts(models.Model):
....
vendor = models.ForeignKey('Vendors', related_name='contacts', on_delete=models.CASCADE)
email = models.CharField(max_length=80, blank=True, null=True, unique=True)
def clean(self):
if self.email:
self.email = self.email.lower()
serializer.py
class VendorContactSerializer(serializers.ModelSerializer):
class Meta:
model = VendorContacts
fields = (
...
'email',)
class VendorsSerializer(serializers.ModelSerializer):
contacts = VendorContactSerializer(many=True)
class Meta:
model = Vendors
fields = (...
'nda',
'contacts',
)
def create(self, validated_data):
contact_data = validated_data.pop('contacts')
vendor = Vendors.objects.create(**validated_data)
for data in contact_data:
VendorContacts.objects.create(vendor=vendor, **data)
return vendor
views.py
class VendorsCreateView(APIView):
"""Create new vendor instances from form"""
permission_classes = (permissions.AllowAny,)
serializer_class = VendorsSerializer
def post(self, request, *args, **kwargs):
serializer = VendorsSerializer(data=request.data)
try:
serializer.is_valid(raise_exception=True)
serializer.save()
except ValidationError:
return Response({"errors": (serializer.errors,)},
status=status.HTTP_400_BAD_REQUEST)
else:
return Response(request.data, status=status.HTTP_200_OK)
As I learned from the documentation
Django Rest Framework serializers do not call the Model.clean when
validating model serializers
In dealing with this problem, I found two ways to solve it.
1. using the custom method at serializer. For my case, it looks like
class VendorsSerializer(serializers.ModelSerializer):
contacts = VendorContactSerializer(many=True)
class Meta:
model = Vendors
fields = (...
'nda',
'contacts',
)
def create(self, validated_data):
contact_data = validated_data.pop('contacts')
vendor = Vendors.objects.create(**validated_data)
for data in contact_data:
VendorContacts.objects.create(vendor=vendor, **data)
return vendor
def validate(self, attrs):
instance = Vendors(**attrs)
instance.clean()
return attrs
Using full_clean() method. For me, it looks like
class VendorsSerializer(serializers.ModelSerializer):
contacts = VendorContactSerializer(many=True)
class Meta:
model = Vendors
fields = (...
'nda',
'contacts',
)
def create(self, validated_data):
contact_data = validated_data.pop('contacts')
vendor = Vendors(**validated_data)
vendor.full_clean()
vendor.save()
for data in contact_data:
VendorContacts.objects.create(vendor=vendor, **data)
return vendor
But in both cases, the clean() method is not called. I really don't understand what I'm doing wrong.

In my case I had the same problem but with validation feature
I used the way below and it works for me (not excludes the way found above):
class CustomViewClass(APIView):
def post(self, request, format=None):
prepared_data_variable = 'some data in needed format'
serializer = CustomSerializer(data=request.data)
if serializer.is_valid(self):
serializer.validated_data['field_name'] = prepared_data_variable
serializer.save()
return Response(data=serializer.data, status=status.HTTP_201_CREATED)
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
This string is key for my solution serializer.validated_data['field_name'] = prepared_data_variable

For DRF you can change your serializer before save as below...
First of all, you should check that serializer is valid or not, and if it is valid then change the required object of the serializer and then save that serializer.
if serializer.is_valid():
serializer.object.user_id = 15 # For example
serializer.save()
UPD!
views.py
class VendorsCreateView(APIView):
"""Create new vendor instances from form"""
permission_classes = (permissions.AllowAny,)
serializer_class = VendorsSerializer
def post(self, request, *args, **kwargs):
data = request.data
if data['nda'] == '':
data['nda'] = None
for contact in data['contacts']:
if contact['email']:
print(contact['email'])
contact['email'] = contact['email'].lower()
serializer = VendorsSerializer(data=request.data)
try:
serializer.is_valid(raise_exception=True)
serializer.save()
except ValidationError:
return Response({"errors": (serializer.errors,)},
status=status.HTTP_400_BAD_REQUEST)

To answer your question: just override save() method for your models as written in docs. There you can assign any values to your model instance directly before saving it in database.
Also, you should probably use models.EmailField for your email fields which will get rid of your lower() check.

Django-rest serializer returning code instead of list of objects

I have an endpoint in my Django-rest application in which I expect to receive the following get response:
{
"my_objects": [
{
"my_object_order": 1,
"related_topics": [{"title": "my_title", "subtitle": "my_subtitle"}, {"title": "my_title2", "subtitle": "my_subtitle2"}],
"collected_at": "2016-05-02T20:52:38.989Z",
}]
}
In order to achieve that, below you can observe my serializers.py
class TopicSerializer(serializers.ModelSerializer):
class Meta:
model = MyTopic
fields = ["title", "subtitle"]
class MyObjectSerializer(serializers.ModelSerializer):
related_topics = TopicSerializer(many=True)
class Meta:
model = MyObject
fields = ("my_object_order",
"related_topics")
def create(self, validated_data):
"""
Saving serialized data
"""
related_topics_list = validated_data.pop("related_topics", [])
obj = MyObject.objects.create(**validated_data)
for topics_data in related_topics_list:
MyTopic.objects.create(trend=trend, **topics_data)
return obj
As suggested, here you can see my models.py
class MyObject(models.Model):
my_object_order = models.IntegerField()
collected_at = models.DateTimeField(auto_now=True)
def __unicode__(self):
return self.story_title
class MyTopic(models.Model):
my_obj = models.ForeignKey(MyObject, related_name="related_topics")
title = models.CharField(max_length=50, blank=False, null=True)
subtitle = models.CharField(max_length=50, blank=True, null=True)
def __unicode__(self):
return self.title
Below you have the excerpt from my views.py
def get(self, request):
params = request.QUERY_PARAMS
# Filtering data
obj_list = my_fun(MyObject, params)
response = {"my_objects": obj_list.values("my_object_order",
"collected_at",
"related_topics")}
return Response(response)
I have looked on the documentation, however I am confused/not understanding fundamentally what I should do.

Your problem is in views.py, you are not using actually the serializer at all. You are just filter some data and return whatever values you get from database (hence the ids only).
I suggest you to check Generic Class Based Views
from myapp.models import MyObject
from myapp.serializers import MyObjectSerializer
from rest_framework import generics
class MyObjectListAPIView(generics.ListAPIView):
queryset = MyObject.objects.all()
serializer_class = MyObjectSerializer
Also if you need any filtering check documentation here. Basically you can filter by fields from model with this snippet
filter_backends = (filters.DjangoFilterBackend,)
filter_fields = ('field1', 'field2')
PS: You can do the view as normal function, but you have to handle yourself filtering/serialization part, the code may not look as cleaner as you get with class based views.

Django serializer Imagefield to get full URL

I am beginner to Django and currently, I can construct model like this.
models.py
class Car(models.Model):
name = models.CharField(max_length=255)
price = models.DecimalField(max_digits=5, decimal_places=2)
photo = models.ImageField(upload_to='cars')
serializers.py
class CarSerializer(serializers.ModelSerializer):
class Meta:
model = Car
fields = ('id','name','price', 'photo')
views.py
class CarView(APIView):
permission_classes = ()
def get(self, request):
car = Car.objects.all()
serializer = CarSerializer(car)
return Response(serializer.data)
For photo, it doesn't show full URL. How can I show full URL?

Django is not providing an absolute URL to the image stored in a models.ImageField (at least if you don't include the domain name in the MEDIA_URL; including the domain is not recommended, except of you are hosting your media files on a different server (e.g. aws)).
However, you can modify your serializer to return the absolute URL of your photo by using a custom serializers.SerializerMethodField. In this case, your serializer needs to be changed as follows:
class CarSerializer(serializers.ModelSerializer):
photo_url = serializers.SerializerMethodField()
class Meta:
model = Car
fields = ('id','name','price', 'photo_url')
def get_photo_url(self, car):
request = self.context.get('request')
photo_url = car.photo.url
return request.build_absolute_uri(photo_url)
Also make sure that you have set Django's MEDIA_ROOTand MEDIA_URL parameters and that you can access a photo via your browser http://localhost:8000/path/to/your/image.jpg.
As piling pointed out, you need to add the request while initialising the serializer in your views.py:
def my_view(request):
…
car_serializer = CarSerializer(car, context={"request": request})
car_serializer.data

For future visitors, there is no need to add another field to the serializer if the view method already returns a serialized object. The only thing required is to add the context since it is needed to generate hyperlinks, as stated in the drf documentation
#list_route()
def my_view(self, request):
qs = Object.objects.all()
return Response(MySerializer(qs, many=True, context={'request': request}).data)

Serializer class
class CarSerializer(serializers.ModelSerializer):
photo_url = serializers.ImageField(max_length=None, use_url=True, allow_null=True, required=False)
class Meta:
model = Car
fields = ('id','name','price', 'photo_url')
View
class CarView(APIView):
def get(self, request, *args, **kwargs):
queryset = Car.objects.all()
serializer = CarSerializer(queryset, many=True, context={"request":request})
return Response(serializer.data, status=status.HTTP_200_OK)

It's better to use this code, due to the above code doesn't check the image is null able or not.
class CarSerializer(serializers.ModelSerializer):
photo_url = serializers.SerializerMethodField()
class Meta:
model = Car
fields = ('id','name','price', 'photo_url')
def get_photo_url(self, car):
request = self.context.get('request')
if photo and hasattr(photo, 'url'):
photo_url = car.photo.url
return request.build_absolute_uri(photo_url)
else:
return None

serializers.py
class BannerSerializer(serializers.ModelSerializer):
image = serializers.SerializerMethodField()
def get_image(self, obj):
return self.context['request'].build_absolute_uri( obj.image.url)
views.py
banner = Banner.objects.all()
banner_data = BannerSerializer(banner,many=True, context={'request': request})
data = banner_data.data
return Response({"data":data})

I read the implement of the Serializer, and find the simplest way is to extends ImageField:
from django.db import models
class ImageField(models.ImageField):
def value_to_string(self, obj): # obj is Model instance, in this case, obj is 'Class'
return obj.fig.url # not return self.url
class Class(models.Model):
name = models.CharField(max_length=50)
intro = models.CharField(max_length=200)
# fig = models.ImageField(upload_to="classes")
fig = ImageField(upload_to="classes")
def __str__(self):
return repr(self,"name")