Django: Get current username in model field as default value - django

# models.py
from django.db import models
from django.contrib.auth.models import User
class SiteInfo(models.Model):
site_owner = models.OneToOneField(User, on_delete=models.CASCADE, )
site_url = models.CharField(max_length=40, unique=True, blank=False, default= site_owner, )
How to make "site_url" default value = User.username or site_owner instance?

As far as I know, I don't know exactly how to set a default value the way you want to, but you can override the save method, it does the same thing
from django.db import models
from django.contrib.auth.models import User
class SiteInfo(models.Model):
site_owner = models.OneToOneField(User, on_delete=models.CASCADE, )
site_url = models.CharField(max_length=40, unique=True, blank=False)
def save(self, *args, **kwargs):
if self.pk is None:
self.url = self.user.username
super(SiteInfo,self).save(*args,**kwargs)

You could use a pre_save signal handler.
from django.db.models.signals import pre_save
from django.dispatch import receiver
#receiver(pre_save, sender=SiteInfo)
def default_site_url(sender, instance, **kwargs):
if not instance.site_url:
instance.site_url = instance.site_owner.username
You would need to set blank=True on the site_url model attribute otherwise form validation would never allow a blank site_url to be added in the first place.

Related

My views.py is returning null from django admin object

I would really appreciate some help on this because I'm completely stuck. I've started up a simple django app (trying to make an instagram clone). However, when I try to display the post objects (which I created in the django admin page) nothing is displayed in index.html, so I tried printing out the objects in the views.py and it's returning to me an empty query set. I don't quite understand what I'm doing wrong and why I can't access the objects? When I print out the username I am able to get that, but then nothing for both post and stream objects. Please I'm so stuck any advice would be appreciated.
views.py
from django.shortcuts import render
from django.contrib.auth.decorators import login_required
from django.template import loader
from django.http import HttpResponse
# Create your views here.
from post.models import post, stream
#login_required
# we are getting all of the string objects that are created for the user
def index(request):
user = request.user
print(user)
posts = stream.objects.filter(user=user)
print(posts)
group_ids = []
#then looping through and getting post id to a list
for posted in posts:
group_ids.append(posted.post_id)
print(group_ids)
#then filtering them so that you can display it in the index
#selecting a specific post by id
post_items = post.objects.filter(id__in=group_ids).all().order_by('-date')
template = loader.get_template('index.html')
context = {'post_items' : post_items}
return(HttpResponse(template.render(context, request)))
models.py
from django.db import models
from django.contrib.auth.models import User
import uuid
# Create your models here.
from django.db.models.signals import post_save
from django.utils.text import slugify
from django.urls import reverse
def user_directory_path(instance,filename):
# this file is going to be uploaded to the MEDIA_ROOT /user(id)/filename
return('user_{0}/{1}'.format(instance.user.id,filename))
class tag(models.Model):
title = models.CharField(max_length = 80, verbose_name = 'tag')
slug = models.SlugField(null = False, unique = True)
class Meta:
verbose_name = 'tag'
verbose_name_plural = 'tags'
# for when people click on the tags we can give them a url for that
# def get_absolute_url(self):
# return(reverse('tags', args = [self,slug]))
def __str__(self):
return(self.title)
def save(self,*args, **kwargs):
if not self.slug:
self.slug = slugify(self.title)
return(super().save(*args, **kwargs))
class post(models.Model):
# will create a long id for each post
id = models.UUIDField(primary_key=True, default = uuid.uuid4, editable = False)
image = models.ImageField(upload_to = user_directory_path, verbose_name= 'image', null = True)
caption = models.TextField(max_length = 2000, verbose_name = 'caption')
date = models.DateTimeField(auto_now_add = True)
tags = models.ManyToManyField(tag, related_name='tags')
user = models.ForeignKey(User, on_delete=models.CASCADE)
likes = models.IntegerField()
def get_absolute_url(self):
return reverse('postdetails', args=[str(self.id)])
# def __str__(self):
# return(self.user.username)
class follow(models.Model):
follower = models.ForeignKey(User, on_delete=models.CASCADE, related_name='follower')
following = models.ForeignKey(User, on_delete=models.CASCADE, related_name='following')
class stream(models.Model):
following = models.ForeignKey(User, on_delete=models.CASCADE, related_name='stream_following')
user = models.ForeignKey(User, on_delete=models.CASCADE)
post = models.ForeignKey(post, on_delete=models.CASCADE)
date = models.DateTimeField()
def add_post(sender, instance,*args, **kwargs):
# here we are filtering all the users that are following you
post = instance
user = post.user
followers = follow.objects.all().filter(following=user)
for follower in followers:
streams = stream(post=post, user=follower.follower, date = post.date, following = user)
streams.save()
post_save.connect(stream.add_post, sender=post)
output from print statements
user
<QuerySet []>
[]
I figured it out. It wasn't an issue with the code, but the way that I was creating posts in the admin panel. So because you can only view posts from users that you are following, the posts that I was creating weren't showing up. So I had to create another user, and follow that user, then have the new user post something. Then the post shows up in the page!

How to refer to django foreign key?

I used to use a OneToOneField relation to the User model, but I had to switch to foreign key (because I want to store multiple dates for 1 user). And now I can't seem to figure out how to refer to my data inside my view.
view.py
def get_data(request, *args,**kwargs):
data = {
'weight': request.user.user_profile.weight,
'goal': request.user.user_profile.goal,
'date': request.user.user_profile.created_at,
}
return JsonResponse(data)
models.py
from django.db import models
from django.contrib.auth.models import User
from django.db.models.signals import post_save
from django.dispatch import receiver
from datetime import date
# Create your models here.
class Profile(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='user_profile')
weight = models.FloatField(max_length=20, blank=True, null=True)
height = models.FloatField(max_length=20, blank=True, null=True)
goal = models.FloatField(max_length=20, blank=True, null=True)
created_at = models.DateField(auto_now_add=True)
def __str__(self):
return self.user.username
#receiver(post_save, sender=User)
def save_user_profile(sender, instance, created, **kwargs):
if created:
Profile.objects.create(user=instance)
I think you should keep OneToOne field. If you want multiple dates you can create ForeignKey for the dates.
If you still want ForeignKey Profile-User, you can try to filter the Profile model, to get the particular profile you need, by username, date etc.:
profile = Profile.objects.get(user=request.user, created_at=request.user.date_joined)
data = {
'weight': profile.weight,
'goal': profile.goal,
'date': profile.created_at,
}

Django User Profile - default value depend on chosen User

I want to create Profile extending User model.
from django.db import models
from django.contrib.auth.models import User
from rest_framework.authtoken.models import Token
# Create your models here.
class Profile(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
operatorId = models.CharField(
max_length=50,
default= 'O'+str(user.id), #get user id
blank=False,
unique=True,
)
Want to add operatorId which depends on userId chosen (operator id i O and user.id as a string). How to get current user id? basically, I need to change default every-time I change user. Is it possible?
you should override save method
from django.db import models
from django.contrib.auth.models import User
from rest_framework.authtoken.models import Token
class Profile(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
operatorId = models.CharField(
max_length=50,
blank=False,
unique=True,
)
def save(self, *args, **kwargs):
self.operatorId = 'O'+str(self.user.id) # set operatorId here
super().save(*args, **kwargs)
note that overriding save has a limitation:
Unfortunately, there isn’t a workaround when creating or updating
objects in bulk, since none of save(), pre_save, and post_save are
called.
check django docs for more info

Django: How to create a record in different app/model post saving the data in current model

Following are my apps and respective models:
Project name: django03
app: home
home/model.py
from __future__ import unicode_literals
from django.db import models
from django.conf import settings
# Create your models here.
User = settings.AUTH_USER_MODEL
HOME_TYPE = (
('1','1'),
('2','2'),
('3','3'),
)
class Home(models.Model):
home_owner = models.ForeignKey(User,null=False, verbose_name='Owner')
hometype= models.CharField(max_length=100, null=False, default=1,
choices=HOME_TYPE, verbose_name='Home Type')
licenseid= models.CharField(max_length=200, null=False, unique=True,
verbose_name='License ID')
archive = models.BooleanField(default=False)
def __str__(self):
return self.licenseid
app: furniture
furniture/model.py
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.conf import settings
from django.db import models
# Create your models here.
User = settings.AUTH_USER_MODEL
FURNITURE_DATA_IMPORT_SOURCE= (
('0', '0'),
('1', '1'),
('2', '2'),
)
class Furniture(models.Model):
furniture_owner = models.ForeignKey(User, verbose_name='User')
furniture_imported_via = models.CharField(max_length=200, default="0", null=False, choices=FURNITURE_DATA_IMPORT_SOURCE, verbose_name='Source of import')
furniture_title = models.CharField(max_length=100, null=False, verbose_name='Furniture title')
furniture_description = models.TextField(max_length=250, verbose_name='Furniture description')
archive = models.BooleanField(default=False)
def __str__(self):
return self.furniture_title
app:mappings
mappings/model.py
from __future__ import unicode_literals
from django.db import models
from home.models import Home
from furniture.models import Furniture
class HomeFurnitureMapping(models.Model):
home = models.OneToOneField(
Home,
on_delete=models.CASCADE,
null=False,
unique=True,
verbose_name='Home'
)
furniture = models.OneToOneField(
Furniture,
on_delete=models.CASCADE,
null=False,
unique=True,
verbose_name='Furniture'
)
app: furnitureupdates
furnitureupdates/model.py
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import models
from mappings.models import HomeFurnitureMapping
# Create your models here.
class FurnitureUpdate(models.Model):
mapping_id = models.OneToOneField(
HomeFurnitureMapping,
on_delete=models.CASCADE,
null=False,
unique=True,
verbose_name='Mapping ID'
)
update_status = models.IntegerField(null=False, default=1)
update_date = models.DateField(auto_now_add=True, null=False, verbose_name='Update date')
update_time = models.TimeField(auto_now_add=True, null=False, verbose_name='Update time')
def __str__(self):
return self.mapping_id
My questions are:
How to create/update a record in "FurnitureUpdate" table after I save/update "Furniture" form from admin panel?
How to create/update a record in "FurnitureUpdate" table after I save/update "HomeFurnitureMapping" form from admin panel
And can this functionality to update "FurnitureUpdate" table be retained if I use django-excel like bulk data upload packages?
Update:
I tried django signals, by adding method in "HomeFurnitureMapping" class:
# method for updating
def update_on_home_furniture_mapping(sender, instance, **kwargs):
print ('ENTERED')
print(instance.id)
m_id = instance.id
from updates.models import FurnitureUpdate
FurnitureUpdate.objects.create(mapping_id = m_id)
print ('Furniture Update created!')
# register the signal
post_save.connect(update_on_tag_product_mapping, sender= HomeFurnitureMapping)
But I get the following error on form submission in admin panel.
Error: "FurnitureUpdate.mapping_id" must be a "HomeFurnitureMapping" instance.
your last error fix by remove id:
replace
FurnitureUpdate.objects.create(mapping_id = m_id)
to
FurnitureUpdate.objects.create(mapping_id = instance)
by default in the db django added _id to the name of columns, and in your case columns inside database looks like COLUMN_NAME_id_id double id at the end, so if you want send foreign key as integer you need use double _id_id, but for single _id you need send an instance.

Django accessing ManyToMany fields from post_save signal

I have a Django model and I want to modify the object permissions on or just after save. I have tried a few solutions and the post_save signal seemed the best candidate for what I want to do:
class Project(models.Model):
title = models.CharField(max_length=755, default='default')
assigned_to = models.ManyToManyField(
User, default=None, blank=True, null=True
)
created_by = models.ForeignKey(
User,
related_name="%(app_label)s_%(class)s_related"
)
#receiver(post_save, sender=Project)
def assign_project_perms(sender, instance, **kwargs):
print("instance title: "+str(instance.title))
print("instance assigned_to: "+str(instance.assigned_to.all()))
In this case, when a Project is created, the signal fires and I see the title, but an empty list for the assigned_to field.
How can I access the saved assigned_to data following save?
You're not going to. M2Ms are saved after instances are saved and thus there won't be any record at all of the m2m updates. Further issues (even if you solve that) are that you're still in a transaction and querying the DB won't get you m2m with proper states anyways.
The solution is to hook into the m2m_changed signal instead of post_save.
https://docs.djangoproject.com/en/dev/ref/signals/#m2m-changed
Your sender then would be Project.assigned_to.through
If your m2m can be empty (blank=True) you are in a little trouble with m2m_changed, because m2m_changed doesn't fire if m2m wasn't set. You can solve this issue by using post_save and m2m_changed at the same time. But there is one big disadvantage with this method - your code will be executed twice if m2m field isn't empty.
So, you can use transaction's on_commit (Django 1.9+)
Django provides the on_commit() function to register callback
functions that should be executed after a transaction is successfully
committed.
from django.db import transaction
def on_transaction_commit(func):
def inner(*args, **kwargs):
transaction.on_commit(lambda: func(*args, **kwargs))
return inner
#receiver(post_save, sender=SomeModel)
#on_transaction_commit
def my_ultimate_func(sender, **kwargs):
# Do things here
Important note: this approach works only if your code calls save().
post_save signal doesn't fire at all in cases when you call only instance.m2m.add() or instance.m2m.set().
Use transaction on commit!
from django.db import transaction
#receiver(post_save, sender=Project)
def assign_project_perms(sender, instance, **kwargs):
transaction.on_commit(lambda: print("instance assigned_to: "+str(instance.assigned_to.all())))
here is an example about how to use signal with many to many field (post like and post comments models),
and in my example i have :
like model (Intermediary table for User and Post tables) : the user can add 1 record only in Intermediary table for each post , which means (unique_together = ['user_like', 'post_like']) for this type of many to many relations you can use 'm2m_changed' signals ,
comment model (Intermediary table for User and Post tables): the user can add many records in Intermediary table for each post , (without unique_together ), for this i just use 'post_save, post_delete' signals , but you can use also 'pre_save, pre_delete' if you like ,
and here is both usage example :
from django.db import models
from django.contrib.auth.models import User
from django.db.models.signals import post_save, post_delete, m2m_changed
from django.dispatch import receiver
class Post(models.Model):
post_user = models.ForeignKey(User,related_name='post_user_related', on_delete=models.CASCADE)
post_title = models.CharField(max_length=100)
post_description = models.TextField()
post_image = models.ImageField(upload_to='post_dir', null=True, blank=True)
post_created_date = models.DateTimeField(auto_now_add=True)
post_updated_date = models.DateTimeField(auto_now=True)
post_comments = models.ManyToManyField(
User,
through="Comments",
related_name="post_comments"
)
p_like = models.ManyToManyField(
User, blank=True,
through="LikeIntermediary",
related_name="post_like_rel"
)
class LikeIntermediary(models.Model):
user_like = models.ForeignKey(User ,related_name="related_user_like", on_delete=models.CASCADE)
post_like = models.ForeignKey(Post ,related_name="related_post_like", on_delete=models.CASCADE)
created = models.DateTimeField(auto_now_add=True)
def __str__(self):
return f"{self.user_like} - {self.post_like} "
class Meta:
unique_together = ['user_like', 'post_like']
#receiver(m2m_changed, sender=LikeIntermediary)
def like_updated_channels(sender, instance, **kwargs):
print('this m2m_changed receiver is called, the instance is post id', instance.id)
class Comments(models.Model):
cmt_user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="related_comments_user")
cmt_post = models.ForeignKey(Post, on_delete=models.CASCADE, related_name="related_comments_post")
cmt_created_date = models.DateTimeField(auto_now_add=True)
cmt_comment_body = models.TextField()
cmt_created = models.DateTimeField(auto_now_add=True)
cmt_updated = models.DateTimeField(auto_now=True)
#receiver(post_save, sender=Comments)
def comments_updated_channels(sender, instance, created, **kwargs):
print('this post_save receiver is called, the instance post id', instance.cmt_post.id)
#receiver(post_delete, sender=Comments)
def comments_deleted_channels(sender, instance, **kwargs):
print('this post_save receiver is called, the instance post id', instance.cmt_post.id)
notes :
the instance with 'm2m_changed' it is a post object .
the instance with 'post_save and post_delete' it is a comment object
this is just an example , and change it based on your case/requirements.
i hope this helpful