Django: Populate user ID when saving a model - django

Question

I have a model with a created_by field that is linked to the standard Django User model. I need to automatically populate this with the ID of the current User when the model is saved. I can't do this at the Admin layer, as most parts of the site will not use the built-in Admin. Can anyone advise on how I should go about this?

Answer 1

UPDATE 2020-01-02
⚠ The following answer was never updated to the latest Python and Django versions. Since writing this a few years ago packages have been released to solve this problem. Nowadays I highly recommend using django-crum which implements the same technique but has tests and is updated regularly: https://pypi.org/project/django-crum/
The least obstrusive way is to use a CurrentUserMiddleware to store the current user in a thread local object:
current_user.py
from threading import local
_user = local()
class CurrentUserMiddleware(object):
def process_request(self, request):
_user.value = request.user
def get_current_user():
return _user.value
Now you only need to add this middleware to your MIDDLEWARE_CLASSES after the authentication middleware.
settings.py
MIDDLEWARE_CLASSES = (
...
'django.contrib.auth.middleware.AuthenticationMiddleware',
...
'current_user.CurrentUserMiddleware',
...
)
Your model can now use the get_current_user function to access the user without having to pass the request object around.
models.py
from django.db import models
from current_user import get_current_user
class MyModel(models.Model):
created_by = models.ForeignKey('auth.User', default=get_current_user)
Hint:
If you are using Django CMS you do not even need to define your own CurrentUserMiddleware but can use cms.middleware.user.CurrentUserMiddleware and the cms.utils.permissions.get_current_user function to retrieve the current user.

Answer 2

If you want something that will work both in the admin and elsewhere, you should use a custom modelform. The basic idea is to override the __init__ method to take an extra parameter - request - and store it as an attribute of the form, then also override the save method to set the user id before saving to the database.
class MyModelForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
self.request = kwargs.pop('request', None)
return super(MyModelForm, self).__init__(*args, **kwargs)
def save(self, *args, **kwargs):
kwargs['commit']=False
obj = super(MyModelForm, self).save(*args, **kwargs)
if self.request:
obj.user = self.request.user
obj.save()
return obj

Answer 3

Daniel's answer won't work directly for the admin because you need to pass in the request object. You might be able to do this by overriding the get_form method in your ModelAdmin class but it's probably easier to stay away from the form customisation and just override save_model in your ModelAdmin.
def save_model(self, request, obj, form, change):
"""When creating a new object, set the creator field.
"""
if not change:
obj.creator = request.user
obj.save()

Answer 4

This whole approach bugged the heck out of me. I wanted to say it exactly once, so I implemented it in middleware. Just add WhodidMiddleware after your authentication middleware.
If your created_by & modified_by fields are set to editable = False then you will not have to change any of your forms at all.
"""Add user created_by and modified_by foreign key refs to any model automatically.
Almost entirely taken from https://github.com/Atomidata/django-audit-log/blob/master/audit_log/middleware.py"""
from django.db.models import signals
from django.utils.functional import curry
class WhodidMiddleware(object):
def process_request(self, request):
if not request.method in ('GET', 'HEAD', 'OPTIONS', 'TRACE'):
if hasattr(request, 'user') and request.user.is_authenticated():
user = request.user
else:
user = None
mark_whodid = curry(self.mark_whodid, user)
signals.pre_save.connect(mark_whodid, dispatch_uid = (self.__class__, request,), weak = False)
def process_response(self, request, response):
signals.pre_save.disconnect(dispatch_uid = (self.__class__, request,))
return response
def mark_whodid(self, user, sender, instance, **kwargs):
if 'created_by' in instance._meta.fields and not instance.created_by:
instance.created_by = user
if 'modified_by' in instance._meta.fields:
instance.modified_by = user

Answer 5

here's how I do it with generic views:
class MyView(CreateView):
model = MyModel
def form_valid(self, form):
object = form.save(commit=False)
object.owner = self.request.user
object.save()
return super(MyView, self).form_valid(form)

Answer 6

If you are using class based views Daniel's answer needs more. Add the following to ensure that the request object is available for us in your ModelForm object
class BaseCreateView(CreateView):
def get_form_kwargs(self):
"""
Returns the keyword arguments for instanciating the form.
"""
kwargs = {'initial': self.get_initial()}
if self.request.method in ('POST', 'PUT'):
kwargs.update({
'data': self.request.POST,
'files': self.request.FILES,
'request': self.request})
return kwargs
Also, as already mentioned, you need to return the obj at the end of ModelForm.save()

Answer 7

what is the problem with using something like:
class MyModelForm(forms.ModelForm):
class Meta:
model = MyModel
exclude = ['created_by']
def save(self, user):
obj = super().save(commit = False)
obj.created_by = user
obj.save()
return obj
Now call it like myform.save(request.user) in the views.
here is ModelForm's save function, which has only a commit parameter.

Answer 8

For future references, best solution I found about this subject:
https://pypi.python.org/pypi/django-crum/0.6.1
This library consist of some middleware.
After setting up this libary, simply override the save method of model and do the following,
from crum import get_current_user
def save(self, *args, **kwargs):
user = get_current_user()
if not self.pk:
self.created_by = user
else:
self.changed_by = user
super(Foomodel, self).save(*args, **kwargs)
if you create and abstract model and inherit from it for all your model, you get your auto populated created_by and changed_by fields.

Answer 9

Based on bikeshedder's answer, I found a solution since his did not actually work for me.
app/middleware/current_user.py
from threading import local
_user = local()
class CurrentUserMiddleware(object):
def __init__(self, get_response):
self.get_response = get_response
def __call__(self, request):
_user.value = request.user
return self.get_response(request)
def get_current_user():
return _user.value
settings.py
MIDDLEWARE = [
'django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
'common.middleware.current_user.CurrentUserMiddleware',
]
model.py
from common.middleware import current_user
created_by = models.ForeignKey(User, blank=False, related_name='created_by', editable=False, default=current_user.get_current_user)
I'm using python 3.5 and django 1.11.3

Answer 10

From the Django documentation Models and request.user:
" To track the user that created an object using a CreateView, you can
use a custom ModelForm. In the view, ensure that you
don’t include [the user field] in the list of fields to edit, and override
form_valid() to add the user:
from django.contrib.auth.mixins import LoginRequiredMixin
from django.views.generic.edit import CreateView
from myapp.models import Author
class AuthorCreate(LoginRequiredMixin, CreateView):
model = Author
fields = ['name']
def form_valid(self, form):
form.instance.created_by = self.request.user
return super().form_valid(form)

Answer 11

The 'save' method from forms.ModelForm returns the saved instanced.
You should add one last line to MyModelForm:
...
return obj
This change is necessary if you are using create_object or update_object generic views.
They use the saved object to do the redirect.

Answer 12

I don't believe Daniel's answer is the best there is since it changes the default behaviour of a model form by always saving the object.
The code I would use:
forms.py
from django import forms
class MyModelForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
self.user = kwargs.pop('user', None)
super(MyModelForm, self).__init__(*args, **kwargs)
def save(self, commit=True):
obj = super(MyModelForm, self).save(commit=False)
if obj.created_by_id is None:
obj.created_by = self.user
if commit:
obj.save()
return obj

Answer 13

Note sure if you were looking for this, but adding the following
user = models.ForeignKey('auth.User')
to a model will work to add the user id to the model.
In the following, each hierarchy belongs to a user.
class Hierarchy(models.Model):
user = models.ForeignKey('auth.User')
name = models.CharField(max_length=200)
desc = models.CharField(max_length=1500)