I have done the below post_save signal in my project.
from django.db.models.signals import post_save
from django.contrib.auth.models import User
# CORE - SIGNALS
# Core Signals will operate based on post
def after_save_handler_attr_audit_obj(sender, **kwargs):
print User.get_profile()
if hasattr(kwargs['instance'], 'audit_obj'):
if kwargs['created']:
kwargs['instance'].audit_obj.create(operation="INSERT", operation_by=**USER.ID**).save()
else:
kwargs['instance'].audit_obj.create(operation="UPDATE").save()
# Connect the handler with the post save signal - Django 1.2
post_save.connect(after_save_handler_attr_audit_obj, dispatch_uid="core.models.audit.new")
The operation_by column, I want to get the user_id and store it. Any idea how can do that?
Can't be done. The current user is only available via the request, which is not available when using purely model functionality. Access the user in the view somehow.
I was able to do it by inspecting the stack and looking for the view then looking at the local variables for the view to get the request. It feels like a bit of a hack, but it worked.
import inspect, os
#receiver(post_save, sender=MyModel)
def get_user_in_signal(sender, **kwargs):
for entry in reversed(inspect.stack()):
if os.path.dirname(__file__) + '/views.py' == entry[1]:
try:
user = entry[0].f_locals['request'].user
except:
user = None
break
if user:
# do stuff with the user variable
Ignacio is right. Django's model signals are intended to notify other system components about events associated with instances and their respected data, so I guess it's valid that you cannot, say, access request data from a model post_save signal, unless that request data was stored on or associated with the instance.
I guess there are lots of ways to handle it, ranging from worse to better, but I'd say this is a prime example for creating class-based/function-based generic views that will automatically handle this for you.
Have your views that inherit from CreateView, UpdateView or DeleteView additionally inherit from your AuditMixin class if they handle verbs that operate on models that need to be audited. The AuditMixin can then hook into the views that successfully create\update\delete objects and create an entry in the database.
Makes perfect sense, very clean, easily pluggable and gives birth to happy ponies. Flipside? You'll either have to be on the soon-to-be-released Django 1.3 release or you'll have to spend some time fiddlebending the function-based generic views and providing new ones for each auditing operation.
You can do that with the help of middleware. Create get_request.py in your app. Then
from threading import current_thread
from django.utils.deprecation import MiddlewareMixin
_requests = {}
def current_request():
return _requests.get(current_thread().ident, None)
class RequestMiddleware(MiddlewareMixin):
def process_request(self, request):
_requests[current_thread().ident] = request
def process_response(self, request, response):
# when response is ready, request should be flushed
_requests.pop(current_thread().ident, None)
return response
def process_exception(self, request, exception):
# if an exception has happened, request should be flushed too
_requests.pop(current_thread().ident, None)
Then add this middleware to your settings:
MIDDLEWARE = [
....
'<your_app>.get_request.RequestMiddleware',
]
Then add import to your signals:
from django.db.models.signals import post_save
from django.contrib.auth.models import User
from <your_app>.get_request import current_request
# CORE - SIGNALS
# Core Signals will operate based on post
def after_save_handler_attr_audit_obj(sender, **kwargs):
print(Current User, current_request().user)
print User.get_profile()
if hasattr(kwargs['instance'], 'audit_obj'):
if kwargs['created']:
kwargs['instance'].audit_obj.create(operation="INSERT", operation_by=**USER.ID**).save()
else:
kwargs['instance'].audit_obj.create(operation="UPDATE").save()
# Connect the handler with the post save signal - Django 1.2
post_save.connect(after_save_handler_attr_audit_obj, dispatch_uid="core.models.audit.new")
Why not adding a middleware with something like this :
class RequestMiddleware(object):
thread_local = threading.local()
def process_request(self, request):
RequestMiddleware.thread_local.current_user = request.user
and later in your code (specially in a signal in that topic) :
thread_local = RequestMiddleware.thread_local
if hasattr(thread_local, 'current_user'):
user = thread_local.current_user
else:
user = None
For traceability add two attributes to your Model(created_by and updated_by), in "updated_by" save the last user who modified the record. Then in your signal you have the user:
models.py:
class Question(models.Model):
question_text = models.CharField(max_length=200)
pub_date = models.DateTimeField('date published')
created_by = models. (max_length=100)
updated_by = models. (max_length=100)
views.py
p = Question.objects.get(pk=1)
p.question_text = 'some new text'
p.updated_by = request.user
p.save()
signals.py
#receiver(pre_save, sender=Question)
def do_something(sender, instance, **kwargs):
try:
obj = Question.objects.get(pk=instance.pk)
except sender.DoesNotExist:
pass
else:
if not obj.user == instance.user: # Field has changed
# do something
print('change: user, old=%s new=%s' % (obj.user, instance.user))
You could also use django-reversion for this purpose, e.g.
from reversion.signals import post_revision_commit
import reversion
#receiver(post_save)
def post_revision_commit(sender, **kwargs):
if reversion.is_active():
print(reversion.get_user())
Read more on their API https://django-reversion.readthedocs.io/en/stable/api.html#revision-api
You can do a small hack by overriding you model save() method and setting the user on the saved instance as additional parameter. To get the user I used get_current_authenticated_user() from django_currentuser.middleware.ThreadLocalUserMiddleware (see https://pypi.org/project/django-currentuser/).
In your models.py:
from django_currentuser.middleware import get_current_authenticated_user
class YourModel(models.Model):
...
...
def save(self, *args, **kwargs):
# Hack to pass the user to post save signal.
self.current_authenticated_user = get_current_authenticated_user()
super(YourModel, self).save(*args, **kwargs)
In your signals.py:
#receiver(post_save, sender=YourModel)
def your_model_saved(sender, instance, **kwargs):
user = getattr(instance, 'current_authenticated_user', None)
PS: Don't forget to add 'django_currentuser.middleware.ThreadLocalUserMiddleware' to your MIDDLEWARE_CLASSES.
I imagine you would have figured this out, but I had the same problem and I realised that all the instances I create had a reference to the user that creates them (which is what you are looking for)
it's possible i guess.
in models.py
class _M(models.Model):
user = models.ForeignKey(...)
in views.py
def _f(request):
_M.objects.create(user=request.user)
in signals.py
#receiver(post_save, sender=_M)
def _p(sender, instance, created, **kwargs):
user = instance.user
No ?
Request object can be obtained from frame record by inspecting.
import inspect
request = [
frame_record[0].f_locals["request"]
for frame_record in inspect.stack()
if frame_record[3] == "get_response"
][0]
def get_requested_user():
import inspect
for frame_record in inspect.stack():
if frame_record[3] == 'get_response':
request = frame_record[0].f_locals['request']
return request.user
else:
return None
context_processors.py
from django.core.cache import cache
def global_variables(request):
cache.set('user', request.user)
----------------------------------
in you model
from django.db.models.signals import pre_delete
from django.dispatch import receiver
from django.core.cache import cache
from news.models import News
#receiver(pre_delete, sender=News)
def news_delete(sender, instance, **kwargs):
user = cache.get('user')
in settings.py
TEMPLATE_CONTEXT_PROCESSORS = (
'web.context_processors.global_variables',
)
I´ve got a model "Comment" and a signal to take actions when a comment is deleted.
The signal executes when deleting the comment in the admin, but not when deleted through django-rest-framework.
#receiver(post_delete, sender=Comment, dispatch_uid=str(uuid.uuid1())) # I tried also removing dispatch_uid
def comment_post_delete(sender, instance, *args, **kwargs):
I´m not really sure if this is related to django-rest-framework but that´s how my app works.
Other thing to note is that many other signals are working just fine.
All the signals are declared in a separate file signals.py and I import it at the end of models.py with a simple import signals
The only difference with other delete operations is that I´m overriding the "destroy" method of the viewset:
class CommentViewSet(mixins.CreateModelMixin,
mixins.DestroyModelMixin,
mixins.ListModelMixin,
viewsets.GenericViewSet):
serializer_class = CommentSerializer
def destroy(self, request, *args, **kwargs):
# only the comment author or the media owner are allowed to delete
instance = self.get_object()
if request.user != instance.user and request.user != instance.media.owner:
error = {'detail': 'No tienes permiso para borrar este comentario'}
return Response(data=error, status=status.HTTP_403_FORBIDDEN)
return super(CommentViewSet, self).destroy(request, args, kwargs)
post_delete and pre_delete will not be fired if the sender parameter does not match the model you are expecting.
To check the sender, create a receiver without sender parameter:
#receiver(post_delete)
def comment_post_delete(sender, instance, *args, **kwargs):
if sender == Comment:
# do something
Why could a signal get dispatched with a different model if the model being saved was "Comment"?
This can happen when django automatically set a deferred model, so when I was expecting a "Comment" I was getting something like "Comment_deferred_somefield".
Django automatic deferring can happen for example when the query is using Model.objects.only('field1', 'field2', 'etc') and there are some missing fields in the only() method
In my sample, signal function was created in models.py.Instead of this,i think it is possible to do using custom signals concept.
my models.py for signals function is
class Book(models.Model):
[..........]
def send_update(sender, instance, created, **kwargs):
if instance.author_name:
message = "Book is updated"
subject = "Updates"
send_mail(subject, message, your_email,
[instance.email,])
post_save.connect(send_update, sender=Book)
views.py is
if request.POST:
form = BookForm(request.POST)
if form.is_valid():
cd = form.cleaned_data
form.save()
return redirect('/index/')
return render_to_response('addbook.html',{ 'form':form },context_instance=RequestContext(request))
Instead of this how can we create a custom signals using signals.py file to send the mail.
I am trying to learn this in practical,an example will help me to do that.
Thanks
signals.py
from django.db.models.signals import post_save
from app.models import Book
def send_update(sender, instance, created, **kwargs):
if instance.author_name:
message = "Book is updated"
subject = "Updates"
send_mail(subject, message, your_email,
[instance.email,])
post_save.connect(send_update, sender=Book)
Register the signals by importing it in the app's __init__.py file. This will allow to import models from signals.py.
__init__.py
import signals
Define your signal and receiver in signals.py:
from django.dispatch import Signal
post_update = Signal(providing_args = ['instance'])
def send_update(...):
....
post_update.connect(send_update, sender = Book)
In views.py, send the signal right after you save the form:
instance = form.save()
post_update.send(sender = Book, instance = instance)
I want to send out an email when a model instance is saved. To do this I listen out for the post_save signal:
#models.py
#receiver(post_save, sender=MyModel, dispatch_uid="something")
def send_email(sender, **kwargs):
instance = kwargs['instance']
email = ModelsEmailMessage(instance)
email.send()
In my view I process the form and append subscribers to the object:
#views.py
object = form.save()
object.subscribers.add(*users)
My problem is that the form save triggers the post_save signal before the users have been added.
But if I do this:
object = form.save(commit=False)
then I can't add m2m instances to an object that has no id.
Heyulp!
Most likely you will have to write your own signal to send email.
Event though you are implemented that tries to send email when object is saved, but that is not what you want. You want to send email when object is saved and has some subscribers added after processing some view. i.e. its 2 step operation.
so i'm making a generic "accounts" page in django. I've used the django-registration plugin, and currently have a (djang-standard) User object, as well as a UserProfile and UserProfileForm object.
This is a question of style, or best-practices, i suppose. Is what i'm planning "right" or is there a "better/recommended/standard way" to do this?
What i'm planning on doing is creating the UserProfile from the request.user ie:
form = UserProfileForm(instance=User)
(and sending that form to the view), and in the UserProfileForm:
class UserProfileForm(forms.ModelForm):
class Meta:
model = UserProfile
def __init__(self,*args,**kwargs):
super(UserProfileForm, self).__init__(*args, **kwargs)
if kwargs.has_key('instance'):
self.user = kwargs['instance']
where my UserProfile is pretty much like so:
class UserProfile(models.Model):
user = models.OneToOneField(User)
points = models.IntegerField(default=0) #how is the user going with scores?
and where User is of the django.contrib.auth.models variety.
Ok! The handling of the editing and saving will either be done via the mixin django stuff or, more likely because i haven't read up on mixins my own user-defined view that handles post and gets. But ignoring that - because i'm sure i should be using the mixins - is the above "right?" or are there suggestions?
cheers!
Take a look at user profiles on the django docs, the basics are listed there. You should also take a look at using a form in a view.
Some specific feedback:
You got the UserProfile model right, but you have to create an instance of one every time a new user is added (either through the admin interface or programmatically in one of your views). You do this by registering to the User post_save signal:
def create_user_profile(sender, instance, created, **kwargs):
if created:
UserProfile.objects.create(user=instance)
post_save.connect(create_user_profile, sender=User)
You should init the ModelForm with an instance of the UserProfile, not User. You can always get the current user profile with request.user.get_profile() (if you define AUTH_PROFILE_MODULE in settings.py). Your view might look something like this:
def editprofile(request):
user_profile = request.user.get_profile()
if request.method == 'POST':
form = UserProfileForm(request.POST, instance=user_profile)
if form.is_valid():
form.save()
return HttpResponseRedirect('/accounts/profile')
else:
form = UserProfileForm(instance=user_profile)
# ...
No need for the init override in your ModelForm. You will be calling it with a UserProfile instance, anyway. If you want to create a new user, just call the User constructor:
user = User()
user.save()
form = UserProfileForm(instance = user.get_profile())
# ...