Django community: Django Q&A RSS
This page, updated regularly, aggregates Django Q&A from the Django community.
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Define a file path for saving uploaded file by users in Django
Consider if we have a form which contains a field to upload a file by users like this : class PoscastForm(forms.ModelForm): class Meta: fields = ("title", "message", "channel", "file", "tag") model = models.Podcast def __ini__(self, *args, **kwargs): user = kwargs.pop("user", None) super().__init__(*args, **kwargs) if user is not None: self.fields["channel"].queryset = ( models.Channel.objects.filter( pk__in = user.channels.value_list('channel__pk') ) ) And the Podcast model: class Podcast(models.Model): title = models.CharField(max_length=255, default='') user = models.ForeignKey(User, related_name="podcasts", on_delete=models.CASCADE, unique=False) created_at = models.DateTimeField(auto_now=True) channel = models.ForeignKey(Channel, related_name="podcasts", null=True, blank=True, on_delete=models.CASCADE) message = models.TextField(blank=True, null=True) message_html = models.TextField(editable=False) tag = models.ForeignKey('podcasts.Tag', related_name="podcasts", null=True, blank=True, on_delete=models.CASCADE) file = models.FileField(blank=True, null=True, default='') So when a user upload his attach file it will save in root directory of my project! How can I change the direction path? The view for this form is look like this : class CreatePodcast(LoginRequiredMixin, SelectRelatedMixin, generic.CreateView): fields = ("title", "message", "channel", "file", "tag") model = models.Podcast def form_valid(self, form): self.object = form.save(commit=False) self.object.user = self.request.user self.object.save() return super().form_valid(form) -
GraphQL/Graphene for backend calls in Django's templates
I just installed Graphene on my Django project and would like to use it also for the back-end, templating. So far, I find just tutorials how to use it only for front-end, no mention about back-end. Should I suppose that it is not a good idea to use it instead of a SQL database? If yes, then why? Is there a downside in the speed in the comparison to a SQL databases like MySQL? What's the best option how to retrieve the data for templates in Python? I mean, best for the performance. Thnx. -
I am getting a double login form with 2 usernames and passwords
I am getting 2 username and password fields on my login page. I tried to make a custom django authentication login page. The first username and password field that appeared on my page is the default login page given by django whereas the second pair is the formatted one which I tried to create using bootstrap. Here are my files: Here is my login.html div class="container"> <form method="POST"> {% csrf_token %} <div class="form-group"> {{form.as_p}} </div> <button type="Submit" class="btn btn-primary"> Log In </button> </form> </div> loginform.py from django import forms from django.contrib.auth.forms import AuthenticationForm class LoginForm(AuthenticationForm): Username = forms.CharField(widget=forms.TextInput(attrs={'class':'form-control'})) Password = forms.CharField(widget=forms.PasswordInput(attrs={'class':'form-control'})) urls.py from django.urls import path from . import views from django.contrib.auth.views import login,logout from .loginform import LoginForm urlpatterns = [ path('', views.HomePageView, name='home'), path('accounts/login', login, {'authentication_form' : LoginForm},name='login'), path('accounts/logout',logout,name='logout') ] -
Django can not save the model inside restless Endpoint
I'm facing with a very strange issue. Basically I've written a JSON interface which a remote server would feed it with log data about a batch. I'm adding each JSON data to BatchStatusLog table, and last log contains extra information about the batch and I'm trying to update the batch with last request. Problem starts here; There are no exception on logs both on local and remote server, everything seems fine. Even I see the log lines after batch.save() but batch could not be updated successfully on database. The strangest one, I've written a small script to mimic server, and it could update the batch!! There is something that I can not see. from restless.views import Endpoint from restless.auth import BasicHttpAuthMixin, login_required from api.authentications import CustomAuthMixin from api.utils import date_with_tz_from_timestamp from splitter.models import Batch, BatchStatusLog class BatchStatusLogEndpoint(Endpoint, BasicHttpAuthMixin): def post(self, request): if request.data is None: return {'is_valid': False, 'message': 'No data'} try: data = request.data['data'] entry = data['status_entry'] batch_id = entry["batch_id"] message = entry["text"] state = entry["state"] item = entry["item"] total_items = entry["numOfItems"] timestamp = entry["timestamp"] except Exception as e: print('EXCEPTION: ' + str(e)) return {'is_valid': False, 'message': 'key {0} is required'.format(str(e))} try: batch = Batch.objects.get(id=batch_id) except Batch.DoesNotExist as e: ... -
firebase storage bucket gives 403 for non authentication required files if files are uploaded via firebase web interface
I have uploaded some static files to the bucket via the web interface of firebase. Here are my security rules: service firebase.storage { match /b/{bucket}/o { match /{allPaths=**} { allow read, write: if request.auth != null; } match /{static=**} { allow read: if request.auth == null } } } If I upload the files via the django admin (using django-storages) I can access the files that are in the static folder without authentication. If I use the firebase webinterface to upload them, I receive a 403. What additional security rule am I missing here? -
How can I only print the the current logged in user data in Django?
from django.db import models from django.contrib import auth from django.urls import reverse from django.contrib.auth.models import User models.py class placement(models.Model): user=models.ForeignKey(User,related_name='placeid', null=True, default=None,on_delete=models.CASCADE) name=models.CharField(max_length=150, blank=True, null=True) ad_space=models.CharField(max_length=100, blank=False, null=False) PID_TYPE = ( ('FN','FORMAT_NATIVE'), ('FNB','FORMAT_NATIVE_BANNER'), ('FI','FORMAT_INTERSTITIAL'), ('FB','FORMAT_BANNER'), ('FMR','FORMAT_MEDIUM,RECT'), ('FRV','FORMAT_REWARDED_VIDEO'), ) format = models.CharField(max_length=3,choices = PID_TYPE,default = 'FN',blank=False, null=False) pid=models.CharField( max_length=50,default='',blank=False, null=False) cpm=models.IntegerField(default=0,blank=False, null=False) ADS_TYPE=( ('FB','FACEBOOK'), ('G','GOOGLE'), ) source=models.CharField(max_length=2,choices=ADS_TYPE,default='FB',blank=False, null=False) comments=models.TextField(default='',blank=False, null=False) objects=models.Manager() def __str__(self): return self.name def get_absolute_url(self): return reverse("dashapp:disp")` views.py class createPlace(LoginRequiredMixin,CreateView): fields=('name','ad_space','format','pid','cpm','source','comments') model=placement template_name='createpl.html' def form_valid(self, form): form.instance.user = User.objects.get(id = self.request.user.id) return super(createPlace, self).form_valid(form) class Idlist(LoginRequiredMixin,ListView): model=placement template_name='placement_list.html' def get_queryset(self): query_set=super().get_queryset() return query_set.filter(placement.objects.filter(user=self.request.user))` Now What query i have to make in Idlist class in Views.py to fetch only the current logged in user related data. And the query that I'm Perfroming in Idlist is giving me error as Exception Type: ValueError Exception Value: too many values to unpack (expected 2) I'm New to to this and any help would be best for me. Please have a look and help a newbie out -
How to avoid Cache error on django 1.11 and redis 3.0
Recently our Redis pack was updated from version 2.10.6 to version 3.0.1. Because of that we start to have a DataError exception, raised when we try to login to django web site. The solution we got was to revert the update and fix the Redis version to 2.10.6, this worked fine, and acording to the Redis docs, this error is expected, as they changed some encoding restrictions: redis-py 3.0 only accepts user data as bytes, strings or numbers (ints, longs and floats). Attempting to specify a key or a value as any other type will raise a DataError exception. My querstion, is that if this is an error with Django 1.11? And, if this is the case, how can we update to Redis 3.0, without getting that raise? -
Best way to count number of records from NDB library
I am developing an application in which I am explicitly using memcache with Google Appengine's NDB library. I want something like this. 1) Get 100 records from datastore and put them in memcache. 2) Now whenever user wants these records I would get these records from memcache instead of datastore. 3) I would invalidate the memcache if there is a new record in datastore and then populate the memcache with 101 records. I am thinking of an approach like I compare the number of records in memcache and datastore and if there is a difference, I would update the memcache. But if we see documentation of NDB, we can only get count by retrieving all the records, and this is not required as datastore query is not being avoided in this way. Any help anyone? Or any different approach I could go with? Thanks in advance. -
Cookie behavior in Django
I've been doing some research on cookies in Django for some time now. However, I don't understand the following. The default setting in django for the SESSION_COOKIE_DOMAIN is None so the domain attribute will be empty. Django sets the session cookie in the session middleware: response.set_cookie( # ... domain=settings.SESSION_COOKIE_DOMAIN, ) The set_cookie function from the response object has the following relevant part if the domain is None which is the default setting in Django: if domain is not None: self.cookies[key]['domain'] = domain Therefore, I assume that the domain in the cookie header is omitted. I've read this great article about cookies and user2864740 made a nice conclusion about it: "When no domain is set in the cookie, the cookie should only match the exact host name of the request. No sub domains, no partial matches. This means simply not including the domain attribute – it is not valid to set an empty domain attribute." 1.) Why does the cookie still work if it's not valid to leave the domain attribute empty or did I missunderstood something here? 2.) Let's assume I own the domain example.com I don't modify the default settings from django so SESSION_COOKIE_DOMAIN is None If I inspect ... -
Defining initial field value in def __init__
I'm struggling to figure out why I'm not able to populate the jurisdiction field with the value indicated in my def init in forms.py. Is there a problem with the way that I'm setting the initial value of this field? I should not that the only thing that doesn't work related to this form is the setting of the initial value. All other functionality works, which is why I haven't included the rest of the code associated with this form. def __init__(self, *args, **kwargs): self.taxtype = kwargs.pop('taxtype',None) self.jurisdiction = kwargs.pop('jurisdiction',None) super(TaxEditForm, self).__init__(*args, **kwargs) if self.taxtype == 1: self.fields['jurisdiction'].choices = [(t.id, t) for t in State.objects.all()] self.fields['jurisdiction'].queryset = State.objects.all() self.fields['jurisdiction'].initial = State.objects.get(name=self.jurisdiction) Thanks! -
Installing Django==2.1.1 from requirements.txt
I am attempting to install from requirements.txt and I get the following exception Could not find a version that satisfies the requirement Django==2.1.1 (from -r requirements.txt (line 12)) (from versions: 1.1.3, 1.1.4, 1.2, 1.2.1, 1.2.2, 1.2.3, 1.2.4, 1.2.5, 1.2.6, 1.2.7, 1.3, 1.3.1, 1.3.2, 1.3.3, 1.3.4, 1.3.5, 1.3.6, 1.3.7, 1.4, 1.4.1, 1.4.2, 1.4.3, 1.4.4, 1.4.5, 1.4.6, 1.4.7, 1.4.8, 1.4.9, 1.4.10, 1.4.11, 1.4.12, 1.4.13, 1.4.14, 1.4.15, 1.4.16, 1.4.17, 1.4.18, 1.4.19, 1.4.20, 1.4.21, 1.4.22, 1.5, 1.5.1, 1.5.2, 1.5.3, 1.5.4, 1.5.5, 1.5.6, 1.5.7, 1.5.8, 1.5.9, 1.5.10, 1.5.11, 1.5.12, 1.6, 1.6.1, 1.6.2, 1.6.3, 1.6.4, 1.6.5, 1.6.6, 1.6.7, 1.6.8, 1.6.9, 1.6.10, 1.6.11, 1.7, 1.7.1, 1.7.2, 1.7.3, 1.7.4, 1.7.5, 1.7.6, 1.7.7, 1.7.8, 1.7.9, 1.7.10, 1.7.11, 1.8a1, 1.8b1, 1.8b2, 1.8rc1, 1.8, 1.8.1, 1.8.2, 1.8.3, 1.8.4, 1.8.5, 1.8.6, 1.8.7, 1.8.8, 1.8.9, 1.8.10, 1.8.11, 1.8.12, 1.8.13, 1.8.14, 1.8.15, 1.8.16, 1.8.17, 1.8.18, 1.8.19, 1.9a1, 1.9b1, 1.9rc1, 1.9rc2, 1.9, 1.9.1, 1.9.2, 1.9.3, 1.9.4, 1.9.5, 1.9.6, 1.9.7, 1.9.8, 1.9.9, 1.9.10, 1.9.11, 1.9.12, 1.9.13, 1.10a1, 1.10b1, 1.10rc1, 1.10, 1.10.1, 1.10.2, 1.10.3, 1.10.4, 1.10.5, 1.10.6, 1.10.7, 1.10.8, 1.11a1, 1.11b1, 1.11rc1, 1.11, 1.11.1, 1.11.2, 1.11.3, 1.11.4, 1.11.5, 1.11.6, 1.11.7, 1.11.8, 1.11.9, 1.11.10, 1.11.11, 1.11.12, 1.11.13, 1.11.14, 1.11.15, 1.11.16, 2.0a1, 2.0b1, 2.0rc1, 2.0, 2.0.1, 2.0.2, 2.0.3, 2.0.4, 2.0.5, 2.0.6, 2.0.7, 2.0.8, 2.0.9) No matching distribution found for ... -
Firebase Messageing for Notification using pyfcm
print(dietitian.dtoken) # recieving registration id here. push_service = FCMNotification(api_key="API-KEY") # registration_id = (dietitian.dtoken) registration_id = json.dumps(dietitian.dtoken) message_title = "xyz" message_body = "Hi " result = push_service.notify_single_device(registration_id=registration_id, message_title=message_title, message_body=message_body) print(result) For this i am getting InvalidRegistration {'multicast_ids': [6833421978764843449], 'success': 0, 'failure': 1, 'canonical_ids': 0, 'results': [{'error': 'InvalidRegistration'}], 'topic_message_id': None} I want to know whether I am sending RegistrationId right or not. I am saving idToken from firebase of users, is it the registrationid or is it something else? -
How to find Only the logged in user content in django?
`class User(auth.models.User,auth.models.PermissionsMixin): def __str__(self): return '@{}'.format(self.username) class placement(models.Model): name=models.CharField(max_length=150, blank=True, null=True) ad_space=models.CharField(max_length=100, blank=False, null=False) PID_TYPE = ( ('FN','FORMAT_NATIVE'), ('FNB','FORMAT_NATIVE_BANNER'), ('FI','FORMAT_INTERSTITIAL'), ('FB','FORMAT_BANNER'), ('FMR','FORMAT_MEDIUM,RECT'), ('FRV','FORMAT_REWARDED_VIDEO'), ) format = models.CharField(max_length=3,choices = PID_TYPE,default = 'FN',blank=False, null=False) pid=models.CharField( max_length=50,default='',blank=False, null=False) cpm=models.IntegerField(default=0,blank=False, null=False) ADS_TYPE=( ('FB','FACEBOOK'), ('G','GOOGLE'), ) source=models.CharField(max_length=2,choices=ADS_TYPE,default='FB',blank=False, null=False) comments=models.TextField(default='',blank=False, null=False) objects=models.Manager() def __str__(self): return self.name def get_absolute_url(self): return reverse("dashapp:disp")` Now what should i do to only get only the logged in user content to be displayed on the template.As currently all the stored data is being fetched . That is logged out user for data is being displayed. I'm Basically a beginner so i dont have any advance idea about this. Full explanation are needed. -
Loop Through List in Django Template
I have a json file 'data' which is a list of dictionaries. One of the keys in every dictionary is 'title' whose value is a a list of titles. How do I display just the first 'title' in this list for every dictionary? The json is as follows: [{'title':['title1','title2,..],'other data':'xyz',...,}...{'title n':['title n1','title n2,..],'other data n1':'xyz n2',...,} This is my views.py: def bill_status(request): data = Status.objects.all() context = {'data':data} return render(request,'billstatus.html',context) In my template I am rendering this as: {% for datum in data %} <h3>{{datum.title}}</h3> {% endfor %} However, the output in html is the entire list for every dictionary: ['title1','title2,..] How do I just output 'title1' rather than the entire list? -
Django - Multiple user types management
I have three user types (differentiated with a non-null user_type field) inherited from the in-built User model. Should I supply a default value for user_type since the ‘createsuperuser’ command fails otherwise? Will this be a problem as by default, an admin’s user_type will be given but the is_superuser will still be False? An article suggested having all account types under the inherited User model. I have separate sign up pages. Should I have separate login pages too? What’s considered a good practice in the industry? Currently I’m using ‘domain//home’ like URLs. I think urls like ‘.domain.com’ are much cleaner. How can this be implemented in django? P.s: Django 2.0, Python 3.6, A beginner. -
How to download a file when a django function is called by javascript instead of navigation to the url?
I have a page where several buttons process different functions like sending a sms (via API), sends a file by email, or downloads a PDF file. Button actions dont use forms, but uses ajax requests via javascript. I used to create a pdf file using javascript (jspdf), but have written code which generates a pdf file by python on the server. Now I need to allow download when the button is clicked. Server code snippet: with NamedTemporaryFile(mode='w+b') as temp: from django.http import FileResponse doc = SimpleDocTemplate(temp.name, pagesize=A4, rightMargin=20, leftMargin=20, topMargin=20, bottomMargin=20, allowSplitting=1, title="Prescription", author="MyOPIP.com") doc.build(elements) print(f'Generated {temp.name}') return FileResponse(open(temp.name, 'rb'), content_type='application/pdf') The above code is supposed to download a pdf file, if called by navigating to the url. On my javascript side, I tried to determine what I'm receiving: $.ajax({ url: `/clinic/${cliniclabel}/prescription/download/patient/${patient_id}`, dataType: "html", data: data, type: 'POST', success: function (data) { console.log("Received data from server..type is ", typeof(data)) console.log(data) } }); And I get: Received data from server..type is string userjs/main.js:2067 %PDF-1.4 %���� ReportLab Generated PDF document http://www.reportlab.com 1 0 obj << /F1 2 0 R /F2 5 0 R >> endobj 2 0 obj.... Apparently django sends this as a file stream. How can I get the file ... -
Django with Channels 2.1.1 Error During WebSocket handshake 404
I am working on a project using Django and Channels 2.1.1. Everything is working splendidly on my home PC but when I deploy to AWS I get the error: 'WebSocket connection to 'ws://IP/ws/lobby/' failed: Error during WebSocket handshake: Unexpected response code: 404 ' which originates from the line in my HTML where I establish the chat socket : var chatSocket = new WebSocket( 'ws://' + window.location.host + '/ws/' + roomName + '/' ); I am using nginx and gunicorn to run my Django application on the host machine. When I went to the Channels 2 tutorial it has a section for testing communication between the channels layer and Redis using the Django Shell which I tested and works. My full code can be seen at https://github.com/Rob-Fox/Chat2 Thank you -
Django Order by on 'related_name' after filtering last record
This is how the sample model looks like models.py class Foo(models.Model): name = models.CharField(max_length=16) class Bar(models.Model): foo = models.ForeignKey(Foo, related_name="get_bars") name = models.CharField(max_length=16) timestamp = models.DateTimeField(auto_now_add=True) Sample Data hello_foo hello_bar Objective: Find all foos sorted by its timestamp in the last connected bar record. (foo is connected to bar with one to many relationship) What I tried I know how to filter foo based on bar foos = hello.models.Foo.objects.filter(get_bars__name="foo1-bar1") I can also order foo based on bar name foos = hello.models.Foo.objects.order_by("-get_bars__name") But how do I use this to perform order by on latest bar record? Sample plain SQL I would write it like this: select foo.name, bar.last_ts from hello_foo as foo inner join (select foo_id, max(timestamp) as last_ts from hello_bar group by foo_id) as bar on foo.id = bar.foo_id order by bar.last_ts desc I am using django 1.11 and python3 -
Why does Django add 'IS NOT NULL' to SQL clause?
I have model: class Profile: ... phone = models.CharField(max_length=50, blank=True, null=True) ... When I run queryset: Profile.objects.exclude(phone='', phone__isnull=True).values('phone') It create SQL code: SELECT "user_profile_profile"."phone" FROM "user_profile_profile" WHERE NOT ("user_profile_profile"."phone" IS NULL AND "user_profile_profile"."phone" = '' AND "user_profile_profile"."phone" IS NOT NULL); args=('',) And it is wrong because it return all phone include phone=None and phone=''. -
DJNAGO add spatial database postgred/postgis error
i try to add a postgresql/postgis in my django app without success. 1.i install GDAL via gohlke. 2.install psycopg2 3.install postgres/postgis database and create a new database if i try to use manage.py for migrate then show me error : django.core.exceptions.ImproperlyConfigured: Could not find the GDAL library (tried "gdal201", "gdal20", "gdal111", "gdal110", "gdal19"). Is GDAL installed? If it is, try setting GDAL_LIBRARY_PATH in your settings. ok i define in settings.py :GDAL_LIBRARY_PATH='C:/Python27/Lib/site-packages/osgeo' And now if i try to use again manage.py then i take this error : Failed to get real commands on module "un2": python process died with code 1: Traceback (most recent call last): File "C:\Program Files\JetBrains\PyCharm 2017.1.5\helpers\pycharm\_jb_manage_tasks_provider.py", line 25, in <module> django.setup() File "C:\Python27\lib\site-packages\django\__init__.py", line 27, in setup apps.populate(settings.INSTALLED_APPS) File "C:\Python27\lib\site-packages\django\apps\registry.py", line 108, in populate app_config.import_models() File "C:\Python27\lib\site-packages\django\apps\config.py", line 202, in import_models self.models_module = import_module(models_module_name) File "C:\Python27\lib\importlib\__init__.py", line 37, in import_module __import__(name) File "C:\Python27\lib\site-packages\django\contrib\auth\models.py", line 4, in <module> from django.contrib.auth.base_user import AbstractBaseUser, BaseUserManager File "C:\Python27\lib\site-packages\django\contrib\auth\base_user.py", line 52, in <module> class AbstractBaseUser(models.Model): File "C:\Python27\lib\site-packages\django\db\models\base.py", line 124, in __new__ new_class.add_to_class('_meta', Options(meta, app_label)) File "C:\Python27\lib\site-packages\django\db\models\base.py", line 325, in add_to_class value.contribute_to_class(cls, name) File "C:\Python27\lib\site-packages\django\db\models\options.py", line 214, in contribute_to_class self.db_table = truncate_name(self.db_table, connection.ops.max_name_length()) File "C:\Python27\lib\site-packages\django\db\__init__.py", line 33, in __getattr__ return getattr(connections[DEFAULT_DB_ALIAS], item) File ... -
Django admin page
I am relatively new to programming and would like to create a note sharing app with django. Is it possible to customize admin page for multiple type of users(super, regular, ordinary(read only) etc) and use it as a base for my application? and if yes, then how? -
how to pass many values through the same variable in Django template
I have a customized search form which has many inputs. Each input comes under specific category. This is about searching for a car. Hence, as a user, you can search for specific car condition, color, size and so on. each category(e.g condition) has many options that you can select from. You can select many conditions. The question is: How can I pass many values (e.g user can select car condition to be new, like new, good) through the same variable (e.g variable name is condition)? also, is it possible to pass all values from different category(e.g car condition, car color, car size) through only one variable(e.g variable name condition)? the last question: what is the best practice to do that? I mean assign each value to different variable or many values with the same category to the same variable or assign all values from different categories to only one variable, if this is possible how can many values be extracted in Django view function? for only one value it can be done by: condition = request.GET.get('condition') Here is portion of the form: <form method="GET" action="{% url 'some url' %}" data-action="" name="options_search" enctype="multipart/form-data" formnovalidate > <ul class="att-list"> <li class="checkbox "> <label> ... -
OpenCV Python, Django and HTML / HTML5?
I am a beginner in OpenCV, Python and Django. I have played around in webcam video capturing and saving the video using OpenCV and python. My question will be, and if someone can provide me simple illustration or code where I can integrate the video capturing and loading of the save video captured into a HTML or web page? I wanted this to be a webpage application where rendered via html or html5? Not sure if it make sense but will be like a dashboard where I can capture, and record the webcam video recordings. Or links to an example will be very helpful. Thanks guys! -
datetime.datetime.strptime('2018-12-16', "%Y-%m-%d").date() doesn't work in my Django query
I can get a queryset by executing on my python console: ClusterHosts.objects.filter(cluster=cluster_id). filter(create_date__gte=datetime.date.today()). filter(create_date__lte=datetime.date.today()). count() I get 49 as the result. But in my serializer I get passed a string for start_date and end_date which both equal '2018-12-16'. So I convert that string to a date like so: sd = datetime.datetime.strptime(start_date, '%Y-%m-%d').date() ed = datetime.datetime.strptime(end_date, '%Y-%m-%d').date() qs = ClusterHosts.objects.filter(cluster=cluster.id). filter(create_date__gte=sd). filter(create_date__lte=ed) But I get an empty query set. What am I doing wrong? -
Python/Django - How to annotate a QuerySet with a value determined by another query
Django 1.11, python 2.7, postgresql I have a set of models that look like this: class Book(Model): released_at=DateTimeField() class BookPrice(Model): price = DecimalField() created_at = DateTimeField() Assuming multiple entries for Book and BookPrice (created at different points in time), I want to get a QuerySet of Book annotated with the BookPrice.price value that was current at the time the Book was released. Something like: books = Book.objects.annotate( old_price=Subquery(BookPrice.objects.filter( created_at__lt=OuterRef('released_at') ) .order_by('created_at') .last() .price ) ) When I try something like this, I get an error: This queryset contains a reference to an outer query and may only be used in a subquery. I could get the data with a for loop easily enough, but I'm trying to prepare a large chunk of data for a CSV download and I don't want to iterate through every book if I can help it.
