My model structure looks like this:
from django.db import models
class Follow(models.Model):
follower = models.ForeignKey('accounts.User', related_name='following',
on_delete=models.CASCADE)
user = models.ForeignKey('accounts.User', related_name='followers',
on_delete=models.CASCADE)
class Meta:
unique_together = (('user', 'follower',),)
def __str__(self):
return f'{self.follower.username} follows {self.user.username}'
I'm looking for something similar to "unique_together" but for the same user.
I know there're possibilities to block it in API but I want it to do it from model level.
You can either:
as the other answer says, override clean() or save() to ensure follower != user,
or if you're using a supported database, you could add a Check constraint to do the same on the database level.
Overriding the save method can do the trick here. In your model save method you can check and raise an exception if both follower and user are same. I don't think you would be able to do it using any constraint as unique_together.
Thanks for the answers but I did it this way.
from django.dispatch import receiver
from django.db import models
from django.db.models.signals import pre_save
from django.core.exceptions import ValidationError
class Follow(models.Model):
follower = models.ForeignKey('accounts.User', related_name='following',
on_delete=models.CASCADE)
user = models.ForeignKey('accounts.User', related_name='followers',
on_delete=models.CASCADE)
class Meta:
unique_together = (('user', 'follower',),)
def __str__(self):
return f'{self.follower.username} follows {self.user.username}'
#receiver(pre_save, sender=Follow)
def check_self_following(sender, instance, **kwargs):
if instance.follower == instance.user:
raise ValidationError('You can not follow yourself')
Related
I have two models, which are User and Record. Each has several fields.
from django.db import models
class User(models.Model):
openid = models.CharField(max_length=20)
nickname = models.CharField(max_length=20,null=True)
def __str__(self):
return self.nickname
class Record(models.Model):
expression = models.CharField(max_length=100)
user = models.ForeignKey(User)
time = models.DateTimeField(auto_now_add=True)
def __str__(self):
return self.expression
I register them in admin.py
from django.contrib import admin
from .models import User,Record
class RecordAdmin(admin.ModelAdmin):
list_display = ('expression','user','time')
class UserAdmin(admin.ModelAdmin):
empty_value_display = "çİş"
list_display = ('openid','nickname')
admin.site.register(User,UserAdmin)
admin.site.register(Record,RecordAdmin)
it works well in django admin initially. but one day, the fields of the Record model disppeared. It looks like
.
No field displays. It makes me unable to modify or add the values of the Record model. The other model User works well and all data exists in database. So why?
I think you just have to add on_delete=models.CASCADE in your ForeignKey Field. When you are using this kind of field, you have to specify the comportment when you make an update, a delete or anything else on this field.
So your script should be like this :
class Record(models.Model):
expression = models.CharField(max_length=100)
user = models.ForeignKey(User, on_delete=models.CASCADE)
time = models.DateTimeField(auto_now_add=True)
def __str__(self):
return self.expression
This is the result :
Edit :
You can also modify null=True by default=null
class User(models.Model):
openid = models.CharField(max_length=20)
nickname = models.CharField(max_length=20,default=null)
def __str__(self):
return self.nickname
So I'm trying to automatically assign the current logged in user to a variable in my model. I think this make sense but I'm not able to migrate the models and it is going me this error.
models.py:
from django.db import models
from django.contrib.auth.models import User
from datetime import date
# Create your models here.
class UserProfileInfo(models.Model):
user = models.OneToOneField(User)
portfolio_site = models.URLField(blank=True)
profile_pic = models.ImageField(upload_to='profile_pics',blank='True')
def __str__(self):
return self.user.username
class UserPosts(models.Model):
post_title = models.CharField(max_length=100,unique=True)
post_sub_title = models.CharField(max_length=250,unique=False)
post_author = models.ForeignKey('User',User.username)
post_date = models.DateField(default=date.today,blank=True)
post_body = models.TextField(max_length=1000,unique=False)
def __str__(self):
return str(self.post_title)
The Error:
ValueError: Cannot create form field for 'post_author' yet, because its related model 'User' has not been loaded yet
Remove the quotation from this line:
post_author = models.ForeignKey('User',User.username)
It should be like this:
post_author = models.ForeignKey(User,User.username)
I think the problem is this:
from django.contrib.auth.models import User
post_author = models.ForeignKey('User',User.username)
Your ForeignKey want's to use the attribute 'username' of the imported User. Not of your User object when related.
I think I just deleted the migrations and then migrated again from scratch...
In my model:
from django.contrib.auth.models import User
class Restaurant(models.Model):
manager = models.ForeignKey(User, on_delete=models.PROTECT,
null=True, blank=False, related_name="manager")
in my serializers.py
class RestaurantSerializer(CoreHyperlinkedModelSerializer):
class Meta:
model = Restaurant
in my views.py
class RestaurantViewSet(viewsets.ModelViewSet):
queryset = Restaurant.objects.order_by('id').all()
serializer_class = RestaurantSerializer
on my list:
the manager is displaying as <rest_framework.relations.PKOnlyObject object at 0x9f7040xbc208>
How can I display it as normal data like its username?
You want to use a 'SlugRelatedField'.
There are a few ways you can go, but if you just want to show a username, all you need is this
from rest_framework import serializers
class RestaurantSerializer(serializers.ModelSerializer):
manager = serializers.CharField(source="manager.username")
class Meta:
model = Restaurant
if you inherit from ModelSerializer and skip the manager field, it will use user PK as the value of the manager field by default.
a slightly more involved way would be to define a separate serializer for User and then embed it in RestaurantSerializer.
from rest_framework import serializers
class UserSerializer(serializers.ModelSerializer):
class Meta:
model = User
class RestaurantSerializer(serializers.ModelSerializer):
manager = UserSerializer()
class Meta:
model = Restaurant
And if you really want to use hyperlinked serializer, you need to do quite a bit of work. You need to read this part carefully http://www.django-rest-framework.org/api-guide/serializers/#how-hyperlinked-views-are-determined
models.py:
import datetime
from django.db import models
from pygments.lexers import get_all_lexers
LEXERS = [item for item in get_all_lexers() if item[1]]
class Classname(models.Model):
class_name = models.CharField(max_length=8)
def __str__(self):
return self.class_name
class Sectionname(models.Model):
class_name = models.ForeignKey(Classname)
section_name = models.CharField(max_length=1, default='A')
def __str__(self):
return self.section_name
class Teachername(models.Model):
classname = models.ForeignKey(Classname, verbose_name='class Name')
secname = models.ForeignKey(Sectionname, verbose_name='sectionname')
teachname = models.CharField(max_length=50, verbose_name='teacher Name')
def __str__(self):
return self.teachname
class Attendancename(models.Model):
teacher_name = models.ForeignKey(Teachername)
date = models.DateField('Date')
intime = models.TimeField('IN-TIME')
outtime = models.TimeField('OUT-TIME')
def hours_conversion(self):
tdelta = (datetime.datetime.combine(datetime.date.today(),self.outtime) - datetime.datetime.combine(datetime.date.today(),self.intime))
hours, minutes = tdelta.seconds//3600, (tdelta.seconds//60)%60
return '{0}hrs {1}mins'.format(hours, minutes)
def __str__(self):
return "%s" %self.teacher_name
serializers.py:
from django.forms import widgets
from rest_framework import serializers
from .models import Classname, Sectionname, Teachername, Attendancename
class ClassSerializer(serializers.ModelSerializer):
class Meta:
model = Classname
fields = ('id', 'class_name',)
class SectionSerializer(serializers.ModelSerializer):
class Meta:
model = Sectionname
fields = ('id', 'class_name', 'section_name')
class TeacherSerializer(serializers.ModelSerializer):
class Meta:
model = Teachername
fields = ('id', 'classname', 'secname', 'teachname')
class AttendanceSerializer(serializers.ModelSerializer):
class Meta:
model = Attendancename
fields = ('id', 'teacher_name', 'date', 'intime', 'outtime')
I want to add owner field in my models to enforce DRF authentication system. Is it necessary to add 'owner' field to all my models above?
I'm following a tutorial on django-rest-framework I have several models as above. Is it possible to make a single model for this authentication purpose and to set permissions in serializers file as per that model & to access all models on the basis of that single model?
I want to add owner field in my models to enforce DRF authentication system
You don't need the owner field to "enforce" the authentication.
How to enable and handle authentication in DRF is explained here in all details: http://www.django-rest-framework.org/api-guide/authentication/
The owner field is only interesting for certain permission cases.
If you look at the docs, you'll see that DRF already ships with permissions for common cases like IsAuthenticated, IsAdmin and many more. Depending on the state of a user (logged in / logged out) he or she might see certain resources or not.
However, if you want to set object level permissions you need the owner field (or something comparable).
How else can you tell if a certain user is really associated with a certain object?
For all this the default User model (from django.contrib.auth) should be completely sufficient and I see no need for any extra models assuming you use one of the standard Authentication Backends which set request.user to an instance of User.
I have an application that makes use of Django's UserProfile to extend the built-in Django User model. Looks a bit like:
class UserProfile(models.Model):
user = models.ForeignKey(User, unique=True)
# Local Stuff
image_url_s = models.CharField(max_length=128, blank=True)
image_url_m = models.CharField(max_length=128, blank=True)
# Admin
class Admin: pass
I have added a new class to my model:
class Team(models.Model):
name = models.CharField(max_length=128)
manager = models.ForeignKey(User, related_name='manager')
members = models.ManyToManyField(User, blank=True)
And it is registered into the Admin:
class TeamAdmin(admin.ModelAdmin):
list_display = ('name', 'manager')
admin.site.register(Team, TeamAdmin)
Alas, in the admin inteface, when I go to select a manager from the drop-down box, or set team members via the multi-select field, they are ordered by the User numeric ID. For the life of me, I can not figure out how to get these sorted.
I have a similar class with:
class Meta:
ordering = ['name']
That works great! But I don't "own" the User class, and when I try this trick in UserAdmin:
class Meta:
ordering = ['username']
I get:
django.core.management.base.CommandError: One or more models did not validate:
events.userprofile: "ordering" refers to "username", a field that doesn't exist.
user.username doesn't work either. I could specify, like image_url_s if I wanted to . . . how can I tell the admin to sort my lists of users by username? Thanks!
This
class Meta:
ordering = ['username']
should be
ordering = ['user__username']
if it's in your UserProfile admin class. That'll stop the exception, but I don't think it helps you.
Ordering the User model as you describe is quite tricky, but see http://code.djangoproject.com/ticket/6089#comment:8 for a solution.
One way would be to define a custom form to use for your Team model in the admin, and override the manager field to use a queryset with the correct ordering:
from django import forms
class TeamForm(forms.ModelForm):
manager = forms.ModelChoiceField(queryset=User.objects.order_by('username'))
class Meta:
model = Team
class TeamAdmin(admin.ModelAdmin):
list_display = ('name', 'manager')
form = TeamForm
This might be dangerous for some reason, but this can be done in one line in your project's models.py file:
User._meta.ordering=["username"]
For me, the only working solution was to use Proxy Model. As stated in the documentation, you can create own proxy models for even built-in models and customize anything like in regular models:
class OrderedUser(User):
class Meta:
proxy = True
ordering = ["username"]
def __str__(self):
return '%s %s' % (self.first_name, self.last_name)
After that, in your model just change Foreign Key to:
user = models.OneToOneField(OrderedUser, unique=True)
or even more suitable
user = models.OneToOneField(OrderedUser, unique = True, parent_link = True)