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Direct assignment to the reverse side of a related set is prohibited. I added a property and got this error

I don't understand why i got this error, I just added a new foreign key property to Rest model and it doesn't work:
Error
TypeError: Direct assignment to the reverse side of a related set is prohibited. Use exercises.set() instead.
I don't know if the name "rest" is causing I already changed the name of the property but I can't make it work.
models.py
class Routine(models.Model):
name = models.CharField(max_length=30)
creation_date = models.DateField(auto_now_add=True)
class Workout(models.Model):
name = models.CharField(max_length=30)
creation_date = models.DateField(auto_now_add=True)
routine = models.ForeignKey(Routine, related_name='workouts', on_delete=models.CASCADE)
class Exercise(models.Model):
index = models.IntegerField()
video_url = models.URLField(max_length=200)
workout = models.ForeignKey(Workout, related_name='exercises', on_delete=models.CASCADE)
class Rest(models.Model):
index = models.IntegerField()
duration = models.IntegerField()
workout = models.ForeignKey(Workout, related_name='rests', on_delete=models.CASCADE)
routine = models.ForeignKey(Routine, related_name='rests', on_delete=models.CASCADE)
serializers.py
class WorkoutSerializer(serializers.ModelSerializer):
exercises = ExerciseSerializer(many=True)
rests = RestSerializer(many=True)
class Meta:
model = Workout
fields = ['id', 'name', 'creation_date', 'exercises', 'rests']
def create(self, validated_data):
exercises_data = validated_data.pop('exercises')
rests_data = validated_data.pop('rests')
workout = Workout.objects.create(**validated_data)
for exercise_data in exercises_data:
Exercise.objects.create(workout=workout, **exercise_data)
for rest_data in rests_data:
Rest.objects.create(workout=workout, **rest_data)
return workout
class RoutineSerializer(serializers.ModelSerializer):
workouts = WorkoutSerializer(many=True)
rests = RestSerializer(many=True)
class Meta:
model = Routine
fields = ['id', 'name', 'creation_date', 'workouts', 'rests']
def create(self, validated_data):
workouts_data = validated_data.pop('workouts')
rests_data = validated_data.pop('rests')
routine = Routine.objects.create(**validated_data)
for workout_data in workouts_data:
Workout.objects.create(routine=routine, **workout_data)
for rest_data in rests_data:
Rest.objects.create(routine=routine, **rest_data)
return routine

Django Rest Framework: How to get instance of related foreign key

Note: IF INFORMATION BELOW IS NOT CLEAR TO UNDERSTAND - PLEASE ASK ME, I WILL UPDATE AND POST INFORMATION YOU NEED | It is important for me
In Warehouse(models.Model) I have amount attribute and
in ChosenProduct(models.Model) - quantity
I'm trying to get amount in Warehouse through chosen_products instance in App_formSerializer to add the quantity of chosen_product
But I can not get the chosen_products objects from instance
--> below Out:
class WarehouseSerializer(serializers.ModelSerializer):
category_name = serializers.ReadOnlyField(
source='category_product.category_name')
posted_user = serializers.ReadOnlyField(
source='posted_user.username')
class Meta:
model = Warehouse
fields = ['id', 'category_product', 'category_name', 'condition',
'product_name', 'amount', 'barcode', 'f_price', 'created_at', 'updated_at', 'posted_user']
class ChosenProductSerializer(serializers.ModelSerializer):
product_info = WarehouseSerializer(source='product', read_only=True)
period_info = Product_periodSerializer(source='period', read_only=True)
class Meta:
model = ChosenProduct
exclude = ('app_form',)
class App_formSerializer(serializers.ModelSerializer):
chosen_products = ChosenProductSerializer(many=True)
def update(self, instance, validated_data):
instance.terminated = validated_data.get('terminated', instance.terminated)
if instance.terminated == True :
print('-----------TRUE--------------------')
print(instance.chosen_products)
print('-----------PRINT--------------------')
instance.save()
return instance
class Meta:
model = App_form
fields = '__all__'
Out
-----------TRUE--------------------
creditapi.ChosenProduct.None
-----------PRINT--------------------
QUESTION UPDATED
models.py
class Warehouse(models.Model):
category_product = models.ForeignKey(
Category_product, on_delete=models.CASCADE)
product_name = models.CharField(max_length=200, unique=True)
condition = models.BooleanField(default=False)
amount = models.IntegerField()
barcode = models.BigIntegerField()
f_price = models.CharField(max_length=255, null=True)
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
posted_user = models.ForeignKey(User, on_delete=models.CASCADE, default=1)
def __str__(self):
return self.product_name
class App_form(models.Model):
phone_regex = RegexValidator(regex=r'^\+?1?\d{9,12}$', message="Phone number must be entered in the format: '998981234567'. Up to 12 digits allowed.")
terminated = models.BooleanField(default=False)
name = models.CharField(max_length=150)
phone_number = models.CharField(validators=[phone_regex], max_length=13)
def __str__(self):
return self.surname
class ChosenProduct(models.Model):
product = models.ForeignKey(Warehouse, on_delete=models.CASCADE)
quantity = models.IntegerField()
app_form = models.ForeignKey(App_form, on_delete=models.CASCADE, related_name='chosen_products')
def __str__(self):
return self.product.product_name

If you write instance.chose_products you access the manager, not the QuerySet that contains the items. You can use .all() to obtain the QuerySet with all the objects:
print(instance.chosen_products.all())
If you access a ForeignKey in reverse, you have a manager, since zero, one, or more elements can refer to the instance.
You can for example aggregate over the chose_products, for example if you want to retrieve the number of related chose_products, you can use:
print(instance.chosen_products.count())
I would however advise not store (aggregated) data in the App_form, but aggregate data when you need it. Data duplication is an anti-pattern, and it turns out it is hard to keep data in sync.

Order post by date

I've created a list of post and now I want order this list by date of publishing. If I use order_by(-post_publishing_date) in the view the shell show me this error:
NameError: name 'post_publishing_date' is not defined
models.py
class PostModel(models.Model):
post_title = models.CharField(max_length=70)
post_short_description = models.TextField(max_length=200)
post_contents = models.TextField()
post_publishing_date = models.DateTimeField(auto_now=False, auto_now_add=True)
post_author = models.ForeignKey(AuthorModel, on_delete=models.CASCADE, related_name="connected_author")
post_keyconcept = models.ManyToManyField(KeyConceptModel, related_name="connected_keyconcept")
slug = models.SlugField(verbose_name="Slug", unique="True")
post_highlighted = models.BooleanField(default=False)
def __str__(self):
return self.post_title
def get_absolute_url(self):
return reverse("singlepostManuscriptusView", kwargs={"slug": self.slug})
class Meta:
verbose_name = "Articolo"
verbose_name_plural = "Articoli"
views.py
class SinglePostGDV(DetailView):
model = PostModel
template_name = "manuscriptus_post_detail.html"
class ListPostGDV(ListView):
model = PostModel
template_name = "manuscriptus_home.html"
queryset = PostModel.objects.filter().order_by(-post_publishing_date)
urls.py
urlpatterns = [
path("it/blog/", ListPostGDV.as_view(), name="homeManuscriptusView"),
path("it/blog/<slug:slug>/", SinglePostGDV.as_view(), name="singlepostManuscriptusView"),
]
What I did wrong?

Ad hoc ordering
Well Python is correct. There is no identifier post_publishing_date, you pass the name of the column through a string, so:
class ListPostGDV(ListView):
model = PostModel
template_name = "manuscriptus_home.html"
queryset = PostModel.objects.filter().order_by('-post_publishing_date')
Define an inherent ordering on the model
Note that you can also give a model an "inherent" ordering in the Meta class:
class PostModel(models.Model):
post_title = models.CharField(max_length=70)
post_short_description = models.TextField(max_length=200)
post_contents = models.TextField()
post_publishing_date = models.DateTimeField(auto_now=False, auto_now_add=True)
post_author = models.ForeignKey(AuthorModel, on_delete=models.CASCADE, related_name="connected_author")
post_keyconcept = models.ManyToManyField(KeyConceptModel, related_name="connected_keyconcept")
slug = models.SlugField(verbose_name="Slug", unique="True")
post_highlighted = models.BooleanField(default=False)
def __str__(self):
return self.post_title
def get_absolute_url(self):
return reverse("singlepostManuscriptusView", kwargs={"slug": self.slug})
class Meta:
ordering = ['-post_publishing_date']
verbose_name = "Articolo"
verbose_name_plural = "Articoli"
If you do this, all queries to this model will implicitly be ordered by -post_publishing_date. So this means that you can not "forget" to order the objects properly.
So then you do not have to order it in the views. You can of course only define one such "inherent" ordering, and it is not clear if you want to use one here.

order_by argument should be string:
queryset = PostModel.objects.filter().order_by('-post_publishing_date')

Object of type 'ListSerializer' is not JSON serializable

I want to get all customer data and responses and also remarks.
This is model.py
class Customer(models.Model):
name = models.CharField(max_length=200)
email_address = models.CharField(max_length=200)
phone_number = models.CharField(max_length=20)
age = models.SmallIntegerField(default=14)
remarks = models.ManyToManyField(Remark,null=True,blank=True)
created_at = models.DateTimeField(auto_now_add=True)
def __str__(self):
return str(self.id)
class Response(models.Model):
question = models.ForeignKey(Question)
customer = models.ForeignKey(Customer)
response_text = models.CharField(max_length=100, null=True, blank=True)
created_at = models.DateTimeField(auto_now_add=True)
uuid = models.UUIDField()
def __str__(self):
return str(self.id)
This is serializers.py
class ResponseSerializer(ModelSerializer):
class Meta:
model = Response
fields = '__all__'
class RemarksSerializer(ModelSerializer):
class Meta:
model = Remark
fields = '__all__'
class CustomerInformationSerializer(ModelSerializer):
remarks = RemarksSerializer(many=True)
responses = serializers.SerializerMethodField()
def get_responses(self, obj):
responses = Response.objects.filter(customer=obj)
return ResponseSerializer(responses, many=True)
class Meta:
model = Customer
fields = ('name', 'email_address', 'phone_number', 'age', 'remarks', 'responses')
This is services.py
def customer_information(company_id=1):
cus = Customer.objects.filter(remarks__company_id=company_id)
return CustomerInformationSerializer(cus, many=True).data
This is views.py
class CustomerInformationView(APIView):
def get(self, request):
company_id = request.GET.get('company_id', 1)
resp = {'data': customer_information(company_id)}
return Response(data=resp, status=status.HTTP_200_OK)
This is url.py
url(r'^customer/$', CustomerInformationView.as_view()),
I'm having this problem. How can I solve this. Kindly guide me.

get function in your view should return responses.data, insted of responsed.

SIDE NOTE
First, let me point you to a resource that I think is GREAT for anything dealing with Django REST Framework:
Classy Django REST Framework. It is a fantastic resource because you can easily dig right into the source code to see how you may or may not need to override default operations.
MY ANSWER
What I suggest is that instead of using the APIView, you use ListAPIView.
It would look something like this:
from rest_framework.generics import ListAPIView
class Customer(models.Model):
name = models.CharField(max_length=200)
email_address = models.CharField(max_length=200)
phone_number = models.CharField(max_length=20)
age = models.SmallIntegerField(default=14)
remarks = models.ManyToManyField(Remark,null=True,blank=True)
created_at = models.DateTimeField(auto_now_add=True)
def __str__(self):
return str(self.id)
class Response(models.Model):
question = models.ForeignKey(Question)
customer = models.ForeignKey(Customer, related_name='responses')
response_text = models.CharField(max_length=100, null=True, blank=True)
created_at = models.DateTimeField(auto_now_add=True)
uuid = models.UUIDField()
def __str__(self):
return str(self.id)
class ResponseSerializer(ModelSerializer):
class Meta:
model = Response
fields = '__all__'
class RemarksSerializer(ModelSerializer):
class Meta:
model = Remark
fields = '__all__'
class CustomerInformationSerializer(ModelSerializer):
remarks = RemarksSerializer(many=True)
responses = ResponseSerializer(many=True)
class Meta:
model = Customer
fields = ('name', 'email_address', 'phone_number', 'age', 'remarks', 'responses')
class CustomerInformationView(ListAPIView):
queryset = Customer.objects.all()
serializer_class = CustomerInformationSerializer
lookup_field = 'remarks__company'
Note the change that I made by adding related_name to the customer field on your Response model. See Django documentation for more information on related_name. In short, it adds responses as a field name on your Customer model so that you can travel backwards through that relationship.
This is not tested, but this should be a better strategy to do what you want without having to have a get_responses method, or a services.py.

Some there might be error because of missing "/" at the end of path like "event-api"=incorrect and "event-api/" correct. That worked for me. Hope you also have same problem.
Incorrect: path('event-api',views.event_view,name="event-view")
Correct: path('event-api/',views.event_view,name="event-view")

How to display a foreign key value instead of the id?

I have the following models :
class FlightSchedule(models.Model):
tail_number = models.ForeignKey(TailNumber, null=False)
flight_number = models.CharField(max_length=30, null=False)
flight_group_code = models.ForeignKey(FlightGroup, null=False)
origin_port_code = models.ForeignKey(Port, null=False, related_name="Origin")
destination_port_code = models.ForeignKey(Port, null=False, related_name="Destination")
flight_departure_time = models.TimeField()
start_date = models.DateField()
end_date = models.DateField()
def __unicode__(self):
return u'%s' % self.flight_number
class Meta:
verbose_name_plural = "Flight Schedule"
class FlightScheduleDetail(models.Model):
flight_date = models.CharField(max_length=30, null=False)
flight_number = models.ForeignKey(FlightSchedule, null=False, related_name="flight_number_schedule")
route_id = models.CharField(max_length=30, null=False, unique=True)
flight_status = models.ForeignKey(Status, null=True, default=1)
def __unicode__(self):
return u'%s' % self.route_id
class Meta:
verbose_name_plural = "Flight Schedule Details"
and the serializer is as below :
class FlightScheduleDetailSerializer(serializers.ModelSerializer):
class Meta:
model = FlightScheduleDetail
fields = '__all__'
class FlightScheduleSerializer(serializers.ModelSerializer):
flight_number_schedule = FlightScheduleDetailSerializer(many=True)
class Meta:
model = FlightSchedule
fields = ['tail_number', 'flight_number', 'origin_port_code', 'destination_port_code', 'flight_departure_time',
'flight_number_schedule']
Here tail_number , flight_number is a foreign key. When I create an API, I get the response as the id of the fields. How can I display the name in the json?
My views.py is as below :
#api_view(['GET'])
def flight_schedule(request):
schedule = FlightSchedule.objects.all()
serializer = FlightScheduleSerializer(schedule, many=True)
return Response(serializer.data)

You can define the source with field_name in your serializer as follows.
I have used source='TailNumber.number'. Please use the right field_name in place of number
class UserProfileSerializer(serializers.ModelSerializer):
tail_number = serializers.CharField(source='TailNumber.number', read_only=True)
flight_number = ....(change as above)
class Meta:
model = FlightSchedule
fields = ['tail_number', 'flight_number', 'origin_port_code', 'destination_port_code', 'flight_departure_time',
'flight_number_schedule']

You could simply add them as if they were attributes.
flight_number_str = serializers.ReadOnlyField(source='flight_number.flight_number')
First flight_number is the attribute of FlightScheduleDetail, then the one of FlightSchedule
and then add it to the list of fields fields = [..., 'flight_number_str']
Otherwise you may have a look at nested relationships in DRF which can offer more possibilities also.

Another alternative is to use the depth option in a serializer. It is to specify nested serialization - doc
class AccountSerializer(serializers.ModelSerializer):
class Meta:
model = Account
fields = ('id', 'account_name', 'users', 'created')
depth = 1
If users is a foreign key or manytomany key the serializer will display the users as an object and not as a key.
The depth option should be set to an integer value that indicates
the depth of relationships that should be traversed before reverting
to a flat representation.