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Django Relational managers

I was trying to delete my Apllication model:
class Application(models.Model):
app_type = models.ForeignKey(ApplicationCategory, on_delete=models.CASCADE, related_name='applications')
fio = models.CharField(max_length=40)
phone_number = models.CharField(max_length=90)
organisation_name = models.CharField(max_length=100, null=True, blank=True)
aid_amount = models.PositiveIntegerField()
pay_type = models.CharField(max_length=1, choices=PAY_CHOICES, default=PAY_CHOICES[0][0])
status = models.ForeignKey(AppStatus, on_delete=models.CASCADE, related_name='applications', null=True, blank=True)
created = models.DateTimeField(auto_now_add=True)
benefactor = models.ForeignKey(Benefactor, on_delete=models.CASCADE, related_name='applications', null=True)
def __str__(self):
return f"id={self.id} li {self.fio} ning mablag\'i!"
and this was my Benefactor model:
class Benefactor(models.Model):
fio = models.CharField(max_length=255)
phone_number = models.CharField(max_length=9)
image = models.ImageField(upload_to='media/')
sponsory_money = models.IntegerField()
organisation_name = models.CharField(max_length=55, null=True, blank=True)
def __str__(self):
return f"{self.fio}"
But I got the below message on superAdmin Panel:
TypeError at /admin/api/benefactor/
create_reverse_many_to_one_manager.\<locals\>.RelatedManager.__call__() missing 1 required keyword-only argument: 'manager'
I would expect delete smoothly!!

Your Benefactor model has several ForeignKey relationships that share the related_name. Give each a unique name and rerun your migrations.

Django: get the max count of a foreign key based on other foreign key

I have this Model:
class Complaint(models.Model):
user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, default=1)
date_created = models.DateTimeField(auto_now_add=True, null=True, blank=True)
name = models.CharField(max_length=255, unique=True)
definition = models.TextField(blank=False, default="")
is_violent = models.BooleanField(default=False)
is_active = models.BooleanField(default=True)
def __str__(self):
return self.name
class Meta:
ordering = ['name']
def get_absolute_url(self):
return reverse('complaint-details', kwargs={'pk': self.pk})
class Service(models.Model):
user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, default=1)
date_created = models.DateTimeField(auto_now_add=True, null=True, blank=True)
name = models.CharField(max_length=255, unique=True)
definition = models.TextField(blank=True, default="")
is_active = models.BooleanField(default=True)
def __str__(self):
return self.name
def get_absolute_url(self):
return reverse('service-details', kwargs={'pk': self.pk})
class Location(models.Model):
user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, default=1)
date_created = models.DateTimeField(auto_now_add=True, null=True, blank=True)
location_name = models.CharField(max_length=255, unique=True)
loc_lat = models.DecimalField(max_digits=9, decimal_places=6)
loc_long = models.DecimalField(max_digits=9, decimal_places=6)
pop = models.PositiveIntegerField(default=500)
is_AOR = models.BooleanField(default=False)
is_active = models.BooleanField(default=True)
def __str__(self):
return self.location_name
class Blotter(models.Model):
user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, default=1)
date_created = models.DateTimeField(auto_now_add=True, null=True, blank=True)#default=timezone.now().date()
date = models.DateField(blank=True)
time = models.TimeField(blank=True)
entry_number = models.CharField(max_length=255, unique=True,validators=[RegexValidator(r'^\d{1,255}$')])
complaints = models.ForeignKey(Complaint, on_delete=models.CASCADE, null=True, blank=True)
service = models.ForeignKey(Service, on_delete=models.CASCADE, null=True, blank=True)
information = models.TextField(blank=False, default="")
location = models.ForeignKey(Location, on_delete=models.CASCADE, null=True, blank=True)
is_active = models.BooleanField(default=True)
class Meta:
ordering = ("date_created",)
def __str__(self):
return (self.entry_number)
def get_absolute_url(self):
return reverse('details-blotter', kwargs={'pk': self.pk})
And I have this serializer:
class APILocationListSerializer(serializers.Serializer):
address = serializers.CharField()
latitude = serializers.DecimalField(max_digits=9, decimal_places=5)
longitude = serializers.DecimalField(max_digits=9, decimal_places=5)
population= serializers.IntegerField()
crime_count=serializers.IntegerField()
crime_rate=serializers.DecimalField(max_digits=4, decimal_places=3)
is_aor = serializers.BooleanField()
class Meta:
model = Blotter
fields= [
'address',
'latitude',
'longitude',
'population',
'crime_count',
'crime_rate'
'is_aor',
]
def to_representation(self, value):
context = {
value['address']:
{
'coordinates':[value['latitude'],value['longitude']],
'Population': value['population'],
'Crime-Count': value['crime_count'],
'Crime-Rate': value['crime_rate'],
'Area-Of-Responsibility': value['is_aor'],
}
}
return context
And ListApiView:
class APILocationList(generics.ListAPIView):
serializer_class = APILocationListSerializer
def get_queryset(self):
q=Blotter.objects.values('location__location_name').annotate(
address=F('location__location_name'),
latitude=F('location__loc_lat'),
longitude=F('location__loc_long'),
population=F('location__pop'),
crime_count=Count('complaints', filter=Q(complaints__is_active=True) and Q(complaints__isnull=False)),
crime_rate=(Cast(F('crime_count'), FloatField())/Cast(F('population'), FloatField()))*100000,
is_aor=F('location__is_AOR')
)
q1 = q.filter(location__is_AOR=True).order_by('address')
query_search = self.request.GET.get("q")
if query_search:
q1 = q.filter(Q(location__is_AOR=True) and Q(location__location_name__icontains=query_search)).order_by('address')
return q1
I'm new to django and DRF. I want to achieve a result like this in my API Not Achieved
but this is the result that i've achieved so far Achieved
As you can see in the picture, I want to count the crime trend (highest count of a crime and the crime itself) in every location.
My questions are:
Is this even achievable/possible to get these results using just one query?
If yes, how?
If no, is there any other way to achieve these kind of results?
Thank you in advance!

Django - conditional foreign key

I have the following 4 models in my program - User, Brand, Agency and Creator.
User is a superset of Brand, Agency and Creator.
A user can be a brand, agency or creator. They cannot take on more than one role. Their role is defined by the accountType property. If they are unset (i.e. 0) then no formal connection exists.
How do I express this in my model?
User model
class User(models.Model):
id = models.UUIDField(primary_key=True, default=uuid4, editable=False)
email = models.EmailField(max_length=255, null=True, default=None)
password = models.CharField(max_length=255, null=True, default=None)
ACCOUNT_CHOICE_UNSET = 0
ACCOUNT_CHOICE_BRAND = 1
ACCOUNT_CHOICE_CREATOR = 2
ACCOUNT_CHOICE_AGENCY = 3
ACCOUNT_CHOICES = (
(ACCOUNT_CHOICE_UNSET, 'Unset'),
(ACCOUNT_CHOICE_BRAND, 'Brand'),
(ACCOUNT_CHOICE_CREATOR, 'Creator'),
(ACCOUNT_CHOICE_AGENCY, 'Agency'),
)
account_id = models.ForeignKey(Brand)
account_type = models.IntegerField(choices=ACCOUNT_CHOICES, default=ACCOUNT_CHOICE_UNSET)
class Meta:
verbose_name_plural = "Users"
def __str__(self):
return "%s" % self.email
Brand model
class Brand(models.Model):
id = models.UUIDField(primary_key=True, default=uuid4, editable=False)
name = models.CharField(max_length=255, null=True, default=None)
brand = models.CharField(max_length=255, null=True, default=None)
email = models.EmailField(max_length=255, null=True, default=None)
phone = models.CharField(max_length=255, null=True, default=None)
website = models.CharField(max_length=255, null=True, default=None)
class Meta:
verbose_name_plural = "Brands"
def __str__(self):
return "%s" % self.brand
Creator model
class Creator(models.Model):
id = models.UUIDField(primary_key=True, default=uuid4, editable=False)
first_name = models.CharField(max_length=255, null=True, default=None)
last_name = models.CharField(max_length=255, null=True, default=None)
email = models.EmailField(max_length=255, null=True, default=None)
youtube_channel_username = models.CharField(max_length=255, null=True, default=None)
youtube_channel_url = models.CharField(max_length=255, null=True, default=None)
youtube_channel_title = models.CharField(max_length=255, null=True, default=None)
youtube_channel_description = models.CharField(max_length=255, null=True, default=None)
photo = models.CharField(max_length=255, null=True, default=None)
youtube_channel_start_date = models.CharField(max_length=255, null=True, default=None)
keywords = models.CharField(max_length=255, null=True, default=None)
no_of_subscribers = models.IntegerField(default=0)
no_of_videos = models.IntegerField(default=0)
no_of_views = models.IntegerField(default=0)
no_of_likes = models.IntegerField(default=0)
no_of_dislikes = models.IntegerField(default=0)
location = models.CharField(max_length=255, null=True, default=None)
avg_views = models.IntegerField(default=0)
GENDER_CHOICE_UNSET = 0
GENDER_CHOICE_MALE = 1
GENDER_CHOICE_FEMALE = 2
GENDER_CHOICES = (
(GENDER_CHOICE_UNSET, 'Unset'),
(GENDER_CHOICE_MALE, 'Male'),
(GENDER_CHOICE_FEMALE, 'Female'),
)
gender = models.IntegerField(choices=GENDER_CHOICES, default=GENDER_CHOICE_UNSET)
class Meta:
verbose_name_plural = "Creators"
def __str__(self):
return "%s %s" % (self.first_name,self.last_name)
Agency model
class Agency(models.Model):
id = models.UUIDField(primary_key=True, default=uuid4, editable=False)
name = models.CharField(max_length=255, null=True, default=None)
agency = models.CharField(max_length=255, null=True, default=None)
email = models.EmailField(max_length=255, null=True, default=None)
phone = models.CharField(max_length=255, null=True, default=None)
website = models.CharField(max_length=255, null=True, default=None)
class Meta:
verbose_name_plural = "Agencies"
def __str__(self):
return "%s" % self.agency
Update:
So I've whittled it down to this bit here in the model:
ACCOUNT_CHOICE_UNSET = 0
ACCOUNT_CHOICE_BRAND = 1
ACCOUNT_CHOICE_CREATOR = 2
ACCOUNT_CHOICE_AGENCY = 3
ACCOUNT_CHOICES = (
(ACCOUNT_CHOICE_UNSET, 'Unset'),
(ACCOUNT_CHOICE_BRAND, 'Brand'),
(ACCOUNT_CHOICE_CREATOR, 'Creator'),
(ACCOUNT_CHOICE_AGENCY, 'Agency'),
)
account_type = models.IntegerField(choices=ACCOUNT_CHOICES, default=ACCOUNT_CHOICE_UNSET)
limit = models.Q(app_label='api', model='Brand') | \
models.Q(app_label='api', model='Creator') | \
models.Q(app_label='api', model='Agency')
content_type = models.ForeignKey(ContentType, limit_choices_to=get_content_type_choices(), related_name='user_content_type')
content_object = GenericForeignKey('content_type', 'email')
If account_type = 1 then link to brand model
If account_type = 2 then link to creator model
If account_type = 3 then link to agency model
How do I accomplish this? Getting this error:
File "/Users/projects/adsoma-api/api/models.py", line 7, in <module>
class User(models.Model):
File "/Users/projects/adsoma-api/api/models.py", line 28, in User
content_type = models.ForeignKey(ContentType, limit_choices_to=get_content_type_choices(), related_name='user_content_type')
NameError: name 'get_content_type_choices' is not defined

Have you tried exploring Django's GenericForeignKey field?
class User(models.Model):
...
limit = models.Q(app_label='your_app_label', model='brand') |
models.Q(app_label='your_app_label', model='creator') |
models.Q(app_label='your_app_label', model='agency')
content_type = models.ForeignKey(ContentType, limit_choices_to=limit, related_name='user_content_type')
object_id = models.UUIDField()
content_object = GenericForeignKey('content_type', 'object_id')
You can access the User's brand/creator/agency by using the following notation:
User.objects.get(pk=1).content_object
This will be an instance of Brand/Creator/Agency as per the content_type.
https://docs.djangoproject.com/en/stable/ref/contrib/contenttypes/#django.contrib.contenttypes.fields.GenericForeignKey
Update based on your comment
Re 1: Using email:
class User(models.Model):
...
email = models.EmailField(max_length=255, unique=True)
limit = models.Q(app_label='your_app_label', model='brand') |
models.Q(app_label='your_app_label', model='creator') |
models.Q(app_label='your_app_label', model='agency')
content_type = models.ForeignKey(ContentType, limit_choices_to=get_content_type_choices, related_name='user_content_type')
content_object = GenericForeignKey('content_type', 'email')
Note: Email can not be a nullable field anywhere if you follow this approach! Also this approach seems hacky/wrong since the email field is now declared in multiple places; and the value can change if you re-assign the content objects. It is much cleaner to link the GenericForeignKey using the discrete UUIDField on each of the other three models
Re 2: Using account_type field:
ContentType is expected to be a reference to a Django Model; therefore it requires choices that are Models and not integers.
The function of limit_choices_to is to perform a filtering such that all possible models are not surfaced as potential GenericForeignKey
class ContentType(models.Model):
app_label = models.CharField(max_length=100)
model = models.CharField(_('python model class name'), max_length=100)
objects = ContentTypeManager()
However, limit_choices_to does accept callables; so you can write a helper method that translates your account_type to the correct Model
I am not clear about how this transaltion should work; so I leave that to you.

Here is how I solve it, override the save method check your condition
tested on Django 3.2
CUSTOMER = [
('customer', 'customer'),
('supplier', 'supplier'),
]
class Customer(models.Model):
name = models.CharField(max_length=256, null=False, blank=False)
user_type = models.CharField(max_length=32, choices=CUSTOMER)
class SupplierOrder(models.Model):
price = models.FloatField(default=0)
supplier = models.ForeignKey(Customer, related_name='supplier', on_delete=models.CASCADE)
def save(self, *args, **kwargs):
supplier = get_object_or_404(Customer, id=self.supplier.id)
if supplier.user_type != 'supplier':
raise ValueError('selected user must be supplier')
super().save(*args, **kwargs)

how to make a django subcategory

How do i make a subcategory for django.
I want something like this Question -> year -> Mathematic
this is my model
class Category(models.Model):
name = models.CharField(max_length=50, unique=True)
def __unicode__(self):
return self.name
class PastQuestion(models.Model):
category = models.ForeignKey(Category)
subject = models.CharField(max_length=128)
question = models.TextField()
posted_by = models.CharField(max_length=50)
def __unicode__(self):
return self.subject`

Create a foreign key to itself:
class Category(models.Model):
...
parent_category = models.ForeignKey('self', null=True, blank=True)
Then, you can assign any existing Category instance as the parent_category of that instance. Furthermore, if you wanted to find all of the subcategories of a given Category instance you would do something like:
subcategories = Category.objects.filter(
parent_category__id=target_category.id)

class Category( models.Model ):
Title = models.CharField( max_length=255, blank=True, null=False, )
parents = models.ForeignKey('self',limit_choices_to = {'parents__isnull': True}, on_delete=models.CASCADE,default=1, blank=True, null=True, )
try

Django: Reference between models

Help!
I have the following 2 models:
class Account(models.Model):
username = models.OneToOneField(User, primary_key=True, unique=True)
receiveaddress = models.CharField(max_length=40, blank=True, null=True, unique=True)
balance = models.DecimalField(max_digits=16, decimal_places=8, default=0)
def __str__(self):
return str(self.username)
class Deposits(models.Model):
receiveaddress = models.CharField(max_length=40, blank=True, null=True, unique=True)
amount = models.DecimalField(max_digits=16, decimal_places=8, default=0)
user = ?????????????????
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
confirmed = models.BooleanField(default=False)
accounted = models.BooleanField(default=False)
def __str__(self):
return str(self.receiveaddress)
Example:
Visualization
My problem:
I want "Deposits.user" to automatically reference the user to which this 'receiveaddress' belongs. In the example, that's TIM. I've wasted 6 hours trying to figure it out, what am I doing wrong?
Thanks in advance.

I think it' just a design matter. Why do you put two fields that have the same information, since the user has account with receiveaddress, adding the user as foreign key will be enough and cleaner, I suggest the following:
class Account(models.Model):
username = models.OneToOneField(User, primary_key=True, unique=True)
receiveaddress = models.CharField(max_length=40, blank=True, null=True, unique=True)
balance = models.DecimalField(max_digits=16, decimal_places=8, default=0)
def __str__(self):
return str(self.username)
class Deposit(models.Model):
amount = models.DecimalField(max_digits=16, decimal_places=8, default=0)
user = models.ForeignKey(User, related_name="deposits")
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
confirmed = models.BooleanField(default=False)
accounted = models.BooleanField(default=False)
def __str__(self):
return str(self.user.account.receiveaddress)
NB: As a convention, models name should be always singular