How to save a User as an attribute of a model Django - django

I am trying to create a Mail function as part of my website, I would like to save the receiving User instead of the receiving User's username in the receiver part of the Mail class, so I don't have to filter the User. This is what I did:
class Mail(models.Model):
sender = models.ForeignKey(User, on_delete=models.CASCADE)
receiver = models.ForeignKey(User, on_delete=models.CASCADE, choices=[(u.username, u) for u in User.objects.all()])
title = models.CharField(max_length=50)
content = models.TextField()
django is giving me this error
ERRORS:
mail.Mail.sender: (fields.E304) Reverse accessor for 'mail.Mail.sender' clashes with reverse accessor for 'mail.Mail.receiver'.
HINT: Add or change a related_name argument to the definition for 'mail.Mail.sender' or 'mail.Mail.receiver'.
mail.Mail.receiver: (fields.E304) Reverse accessor for 'mail.Mail.receiver' clashes with reverse accessor for 'mail.Mail.sender'.
HINT: Add or change a related_name argument to the definition for 'mail.Mail.receiver' or 'mail.Mail.sender'.

You need to add related_name attribute. For more information read this post:
What is related_name used for?
class Mail(models.Model):
sender = models.ForeignKey(User, on_delete=models.CASCADE, related_name='sender')
receiver = models.ForeignKey(User, on_delete=models.CASCADE, choices=[(u.username, u) for u in User.objects.all()], related_name='receiver')
title = models.CharField(max_length=50)
content = models.TextField()

Related

in django two fields with foreign keys from one model to link two fields from another model

I have a "ModelVoiture" model with a foreign key "type_carburant" field and I can access the "typeCarburant" field of the "Carburant" model. I need to access another field of the same model "Carburant", the field "prixCarburant" from the model "ModelVoiture" but if I add the line
prixCarburant = models.ForeignKey(Carburant, on_delete=models.CASCADE)
i have this error
coutcarbur.ModelVoiture.prixCarburant: (fields.E304) Reverse accessor 'Carburant.modelvoiture_set' for 'coutcarbur.ModelVoiture.prixCarburant' clashes with reverse accessor for 'coutcarbur.ModelVoiture.typeCarburant'.
HINT: Add or change a related_name argument to the definition for 'coutcarbur.ModelVoiture.prixCarburant' or 'coutcarbur.ModelVoiture.typeCarburant'.
coutcarbur.ModelVoiture.typeCarburant: (fields.E304) Reverse accessor 'Carburant.modelvoiture_set' for 'coutcarbur.ModelVoiture.typeCarburant' clashes with reverse accessor for 'coutcarbur.ModelVoiture.prixCarburant'.
HINT: Add or change a related_name argument to the definition for 'coutcarbur.ModelVoiture.typeCarburant' or 'coutcarbur.ModelVoiture.prixCarburant'.
my code in coutcarbur/models.py
class MarqueVoiture(models.Model):
name = models.CharField(max_length=50)
def __str__(self):
return self.name
class Carburant(models.Model):
name = models.CharField(max_length=50)
prixCarburant = models.DecimalField(max_digits=6, decimal_places=2)
typeCarburant = models.CharField(max_length=50)
def __str__(self):
return self.name
class ModelVoiture(models.Model):
name = models.CharField(max_length=50)
consolitre = models.DecimalField(
max_digits=6, decimal_places=2)
prixCarburant = models.ForeignKey(Carburant, on_delete=models.CASCADE)
typeCarburant = models.ForeignKey(Carburant, on_delete=models.CASCADE)
marque = models.ForeignKey(MarqueVoiture, on_delete=models.CASCADE)
def __str__(self):
return self.name
how to implement related_name function in template to solve this problem.
I must surely revise the diagram of my models?
thanks for any help.

Inherit from abstract class Django

I am building a platform with 3 users roles: Admin, Creator and Brand. I redefined a default django User to be able to login by email.
class AbstractUser(AbstractBaseUser, PermissionsMixin):
email = models.EmailField(max_length=32, unique=True)
first_name = models.CharField(max_length=32, blank=True)
last_name = models.CharField(max_length=64, blank=True)
is_staff = models.BooleanField(default=False)
is_superuser = models.BooleanField(default=False)
is_active = models.BooleanField(default=True)
date_joined = models.DateTimeField(auto_now_add=True)
location = models.CharField(max_length=120, blank=True)
bio = models.TextField(blank=True)
USERNAME_FIELD = 'email'
EMAIL_FIELD = 'email'
REQUIRED_FIELDS = []
objects = CustomUserManager()
class Meta:
abstract = True
def __str__(self):
return self.email
I made this class an abstract one to be able to add new classes, inherit from the Abstract class and redefine their attributes.
class PlatformAdmin(AbstractUser):
pass
class Creator(AbstractUser):
email = models.EmailField(max_length=32, unique=True, error_messages={
'unique': "A customer with that email already exists.",
})
class Brand(AbstractUser):
name = models.CharField(max_length=64)
I also add in settings.py following:
AUTH_USER_MODEL = 'users.PlatformAdmin'
Now when I run makemigrations it will give the following output:
users.Brand.groups: (fields.E304) Reverse accessor for 'Brand.groups' clashes with reverse accessor for 'Creator.groups'.
HINT: Add or change a related_name argument to the definition for 'Brand.groups' or 'Creator.groups'.
users.Brand.groups: (fields.E304) Reverse accessor for 'Brand.groups' clashes with reverse accessor for 'PlatformAdmin.groups'.
HINT: Add or change a related_name argument to the definition for 'Brand.groups' or 'PlatformAdmin.groups'.
users.Brand.user_permissions: (fields.E304) Reverse accessor for 'Brand.user_permissions' clashes with reverse accessor for 'Creator.user_permissions'.
HINT: Add or change a related_name argument to the definition for 'Brand.user_permissions' or 'Creator.user_permissions'.
users.Brand.user_permissions: (fields.E304) Reverse accessor for 'Brand.user_permissions' clashes with reverse accessor for 'PlatformAdmin.user_permissions'.
HINT: Add or change a related_name argument to the definition for 'Brand.user_permissions' or 'PlatformAdmin.user_permissions'.
users.Creator.groups: (fields.E304) Reverse accessor for 'Creator.groups' clashes with reverse accessor for 'Brand.groups'.
HINT: Add or change a related_name argument to the definition for 'Creator.groups' or 'Brand.groups'.
users.Creator.groups: (fields.E304) Reverse accessor for 'Creator.groups' clashes with reverse accessor for 'PlatformAdmin.groups'.
HINT: Add or change a related_name argument to the definition for 'Creator.groups' or 'PlatformAdmin.groups'.
users.Creator.user_permissions: (fields.E304) Reverse accessor for 'Creator.user_permissions' clashes with reverse accessor for 'Brand.user_permissions'.
HINT: Add or change a related_name argument to the definition for 'Creator.user_permissions' or 'Brand.user_permissions'.
users.Creator.user_permissions: (fields.E304) Reverse accessor for 'Creator.user_permissions' clashes with reverse accessor for 'PlatformAdmin.user_permissions'.
HINT: Add or change a related_name argument to the definition for 'Creator.user_permissions' or 'PlatformAdmin.user_permissions'.
users.PlatformAdmin.groups: (fields.E304) Reverse accessor for 'PlatformAdmin.groups' clashes with reverse accessor for 'Brand.groups'.
HINT: Add or change a related_name argument to the definition for 'PlatformAdmin.groups' or 'Brand.groups'.
users.PlatformAdmin.groups: (fields.E304) Reverse accessor for 'PlatformAdmin.groups' clashes with reverse accessor for 'Creator.groups'.
HINT: Add or change a related_name argument to the definition for 'PlatformAdmin.groups' or 'Creator.groups'.
users.PlatformAdmin.user_permissions: (fields.E304) Reverse accessor for 'PlatformAdmin.user_permissions' clashes with reverse accessor for 'Brand.user_permissions'.
HINT: Add or change a related_name argument to the definition for 'PlatformAdmin.user_permissions' or 'Brand.user_permissions'.
users.PlatformAdmin.user_permissions: (fields.E304) Reverse accessor for 'PlatformAdmin.user_permissions' clashes with reverse accessor for 'Creator.user_permissions'.
HINT: Add or change a related_name argument to the definition for 'PlatformAdmin.user_permissions' or 'Creator.user_permissions'.
I can't figure out what I am doing wrong and how to solve this issue.
I think you have to add 3 fields like this:
class AbstractUser(AbstractBaseUser, PermissionsMixin):
email = models.EmailField(max_length=32, unique=True)
first_name = models.CharField(max_length=32, blank=True)
last_name = models.CharField(max_length=64, blank=True)
is_staff = models.BooleanField(default=False)
is_superuser = models.BooleanField(default=False)
is_active = models.BooleanField(default=True)
date_joined = models.DateTimeField(auto_now_add=True)
location = models.CharField(max_length=120, blank=True)
bio = models.TextField(blank=True)
# add this 3 fields
is_admin = models.BooleanField(default=False)
is_creater = models.BooleanField(default=False)
is_brand = models.BooleanField(default=True)
USERNAME_FIELD = 'email'
EMAIL_FIELD = 'email'
REQUIRED_FIELDS = []
objects = CustomUserManager()
class Meta:
abstract = True
def __str__(self):
return self.email
AUTH_USER_MODEL = 'users.CustomUserModel'
I think you have to follow this method.
inside AbstractUser in class Meta, abstract=True is creating the problem. also you are repeating the email field in 2 places (AbstractUser and Creator).
OR
keep only one user model(PlatformAdmin). convert Creator and Brand as normal model. otherwise fields from PermissionsMixin class are clashing(same fields are repeating in multiple places).

Django getting error: "Reverse accessor for" in Models

I am trying to create a db model using django inspect db and it is generating all the models but I am getting error.
I am using this command to generate db models for existing database:
python manage.py inspectdb > models.py
It is generating models accurately but in fileds such as this:
create_uid = models.ForeignKey('self', models.DO_NOTHING,db_column='create_uid', blank=True, null=True)
write_uid = models.ForeignKey('self',models.DO_NOTHING, db_column='write_uid', blank=True, null=True)
I am getting error:
polls.ResUsers.create_uid: (fields.E304) Reverse accessor for 'ResUsers.create_uid' clashes with reverse accessor for 'ResUsers.write_uid'.
HINT: Add or change a related_name argument to the definition for 'ResUsers.create_uid' or 'ResUsers.write_uid'.
polls.ResUsers.write_uid: (fields.E304) Reverse accessor for 'ResUsers.write_uid' clashes with reverse accessor for 'ResUsers.create_uid'.
HINT: Add or change a related_name argument to the definition for 'ResUsers.write_uid' or 'ResUsers.create_uid'.
I am adding related names like this:
create_uid = models.ForeignKey('self', models.DO_NOTHING,related_name='create_uid',db_column='create_uid', blank=True, null=True)
What should I do in order to use generated models. I am using postgres.
I am updating my question one of the answer worked for me when I am using it like this:
create_uid = models.ForeignKey(
'self',
models.DO_NOTHING,
db_column='create_uid',
related_name='created_items',
blank=True,
null=True
)
In one other model class when I am using this code like this:
create_uid = models.ForeignKey(
'ResUsers',
models.DO_NOTHING,
db_column='create_uid',
related_name='created_items',
blank=True,
null=True
)
I am getting the error:
polls.ResUsers.create_uid: (fields.E304) Reverse accessor for 'ResUsers.create_uid' clashes with reverse accessor for 'SurveyUserInput.create_uid'.
HINT: Add or change a related_name argument to the definition for 'ResUsers.create_uid' or 'SurveyUserInput.create_uid'.
The related_name=… [Django-doc] is the name of the relation in reverse. So it is meant to access all model objects with as create_uid/write_uid the object. This can result in a QuerySet of zero, one or more elements.
Therefore the related_names of two ForeignKeys to the same model, can not be the same, since that would make the model ambiguous. Since your ForeignKeys refer to the 'self' model, you can not even given these the name of a field that already exists.
You thus might want to give the relations a name like:
class MyModel(models.Model):
create_uid = models.ForeignKey(
'self',
models.DO_NOTHING,
db_column='create_uid',
related_name='created_items',
blank=True,
null=True
)
write_uid = models.ForeignKey(
'self',
models.DO_NOTHING,
db_column='write_uid',
related_name='written_items',
blank=True,
null=True
)

related_name argument required

I've recieved the following error and I'm not sure how to handle this in my model.
HINT: Add or change a related_name argument to the definition for 'UserCart.state_tax' or 'UserCart.fed_tax'.
userorders.UserCart.state_tax: (fields.E304) Reverse accessor for 'UserCart.state_tax' clashes with reverse accessor for 'UserCart.other_tax'.
models.py
class UserCart(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE, default=None)
state_tax = models.ForeignKey(Tax, on_delete=models.SET_NULL, null=True)
fed_tax = models.ForeignKey(Tax, on_delete=models.SET_NULL, null=True)
This is here necessary, since you have two references from UserCart to the Tax model. This thus means that the relation in reverse (from Tax to UserCart) can not be usercart_set, since then it is not clear which relation we use in reverse.
We thus should at least give a related name to one of the relations (that is different from usercart_set). For example:
from django.contrib.auth import get_user_model
class UserCart(models.Model):
user = models.ForeignKey(get_user_model(), on_delete=models.CASCADE, default=None)
state_tax = models.ForeignKey(
Tax,
related_name='state_usercarts',
on_delete=models.SET_NULL,
null=True
)
fed_tax = models.ForeignKey(
Tax,
related_name='fed_usercarts',
on_delete=models.SET_NULL,
null=True
)
Note: you might want to make use of get_user_model [Django-doc] over a reference to User itself. If you later change your user model, then the ForeignKey will automatically refer to the new user model.

Two foreign keys of same class Django

How to access the two foreign key's of same class
class Countries(models.Model):
name = models.CharField(max_length=200,null=True)
class bookings(models.Model):
Pickup = models.ForeignKey(Countries,on_delete=models.CASCADE,null=True)
Dropoff = models.ForeignKey(Countries,on_delete=models.CASCADE,null=True)
ERROR reverse accessor of Pickup clashes with reverse accessser for Dropoff
You have to use related name keyword, so that reverse access will be by default it is taking the same name that's why it is conflicting possible.
class bookings(models.Model):
Pickup = models.ForeignKey(Countries,on_delete=models.CASCADE,null=True, related_name="pickup")
Dropoff = models.ForeignKey(Countries,on_delete=models.CASCADE,null=True, related_name="dropoff")
Change your models as below:
class bookings(models.Model):
Pickup = models.ForeignKey(Countries, on_delete=models.CASCADE, null=True, related_name='pickup_countries')
Dropoff = models.ForeignKey(Countries, on_delete=models.CASCADE, null=True, related_name='dropoff_countries')
Reference : Django related_name