django on delete protect. All these steps, including the use of an environment variable for EMAIL_HOST_PASSWORD, and customizing each email are covered in the Django for Beginners. Protect Your Django Web Application From Security Threats be positive to delete the session data for a particular user after his/her log out. You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each example. If you’re using Django REST Framework (DRF), you can validate on a field level inside your serializers. The simplest style of permission would be to allow access to any authenticated user, and deny access to any unauthenticated user. ForeignKey(Album, related_name='tracks') album = models. ; Generate relationship, using cardinality, create suitable fields, OneToOne, ForeingKey and ManyToMany. The framework includes built-in models for Users and Groups (a generic way of applying. How do I set up an SSL Certificate for a Django application? In this tutorial, we'll look at how to secure a containerized Django app running behind an HTTPS Nginx proxy with Let's Encrypt SSL certificates. db import IntegrityError, connections, transaction from django. Yes, it seems that #21734 might be related. The open source option prevents the company from "selling" the code (well, they would look very silly if they tried to do that) and establishes you as the "go to" person for. " Here we will have the detailed explanation of each. DestroyAPIView): queryset = Region. But thats the thing: I'm not doing a rollback. SET_NULL – It assigns NULL to the relational field when a record is deleted, provided null = True is set. PROTECT외래키가 삭제될때 삭제되지 않도록 protected . But sometimes especially in your development environment, you do not want this feature when sending post requests to your web server use curl in the command line, if this feature is enabled, you will get errors. " I've been trying to go to the "Properties" setting and un-check the "Read-only" box but I still cannot save my file in the folder that I want. The basics: Each model is a Python class that subclasses django. Now if I want to delete Tag instance, then also all related Article instances will be deleted. This tutorial assumes you know the basics of Django, including; A basic project layout, How to add a model to Django Admin, Create and apply a database migration. PROTECT, "Protect - Block migrations if records contain removed values"), (models. To delete it you will have to delete all objects that reference it manually. This is a mid-level tutorial for making Django and React work together. One exception is when a CharField has both unique=True and blank=True set. Django has provided a feature that can help you to avoid csrf attacks on your Django application. Every framework has a fingerprint and Django is no exception. PROTECT should prevent deletion of a referenced row even it's attempted through cascading deletion just like ON DELETE RESTRICT does. Actions for the on_delete include: CASCADE. Can someone please tell me what these are and give me a quick example because I can find them documented anywhere : (. This article will tell you how to enable or disable csrf validation in the Django. Again, make sure that the other apps don't make an import from these files. I'm merely looking at a previous version. A slightly less strict style of permission. Transitioning to a secure secret management store such as Vault will greatly improve the security of your application and protect any sensitive data you need to store such as tokens, passwords, certifications, or encryption keys. generic import ProtectedResourceView from django. We can import these exceptions from django. Django: Protect API's using DjangoModelPermissions. The main idea is that your data never actually leaves the database, it’s just marked as deleted. Moreover, we can use admin panel of Django to create, update, delete or retrieve fields of a model and various similar. Django has the build in support for most of the available databases here is the list of most common databases and how to connect them to your django project. The Django Rest Framework Role Filters package provides simple filtering over multiple types of roles. In September 2016, Adam Johnson, Ed Morley, and others gained maintenance responsibility for django-cors-headers from. PROTECT(collector, fields, sub_objs, using)). 또한 참조 된 객체의 삭제를 방지하고 RestrictedError 를 발생시킵니다. CsrfViewMiddleware' to your list of middleware classes, MIDDLEWARE_CLASSES. Django ORM consists of ease of use abstraction. This intermediate-level tutorial is designed for readers who are already familiar with the fundamental design. $ django-admin startproject crudexample. However, if the client is logged in with a session cookie, the rest of the auth method runs and raises a. Or Django Project admin itself :) > > Please stop arguing with us when we already agree with you. Please help me to get rid of this problem. PROTECT on foreign keys corrupt page tree · Issue #3658. Django provides an authentication and authorization ("permission") system, built on top of the session framework discussed in the previous tutorial, that allows you to verify user credentials and define what actions each user is allowed to perform. Adding required permissions to views. If you want to use something like ManifestStaticFilesStorage then you must instead use: STATICFILES_STORAGE = 'storages. Django Rest Framework custom JWT authentication. In this tutorial we are going to explore the specifics of JWT authentication. Blog applications are a common starter project because they involve create, read, update, and delete (CRUD) operations. PROTECT, related_name='recipes',. fields import ReCaptchaField class ReCAPTCHAForm(forms. Django CRUD (Create Read Update Delete) Example. To protect against brute-force attacks against the authentication system, you may consider deploying a Django plugin or web server module to throttle these requests. A model is the single, definitive source of information about your data. To avoid form submits without a valid captcha we can disable the form button. SET_NULL and make sure the field is nullable or set on_delete=models. It is based on MVT (Model View Template) design pattern. Advance the state of the art in Web development. It takes less time to build application after collecting client requirement. Promote the use of Django among the world-wide Web development community. Make your API ¶ We start where we left the part 1 of the tutorial : you have an authorization server and we want it to provide an API to access some kind of resources. Django Models simplify the database and table creation, adding new data or tuples to tables, deleting, retrieval, and modification. PROTECT, # 删除关联数据,引发错误ProtectedError. Subcategory has a protected (on_delete=models. PROTECT: Forbid the deletion of the referenced object. delete () If you need to delete only a specific subset of objects, you can use filter function to select those rows first, and then use delete () function to delete them. In the end, it would be positive to delete the session data for a particular user after they log out. I'm deploying a Django/React app through Azure app service and have configured my. If you open the ModelAdmin class code . タイトル「Djangoのon_delete doって何の処理をしてるの? PROTECT: これはオブジェクトが削除されるときも、参照されたオブジェクトは削除しない . 0 this argument will be mandatory. With Django models, we can easily set up relationships between tables with the help of foreign keys. In this project, you'll use the Django admin to do the heavy CRUD lifting and focus on providing a GraphQL API for your blog data. If the user isn’t logged in, no CSRF token is needed, because the auth method returns before enforcing the CSRF check. The Django Software Foundation would not be able to operate without the generous financial support of our corporate members. from django import forms from django. If not then use pip3 install django==2. Prior to Django 3 we've managed to customize the delete message when you have (say) PROTECT set. Otherwise, become a superuser to remove a file. filter (store=store) if recommendations. If anyone tries to delete an entry on that look-up table, PROTECT prevents them from deleting it if it is tied to any records. @Simon it may be that this cannot be changed in Django without breaking backwards compatibility, but there's an argument to be made for the other proposed behavior: given multiple cascade paths, depending on which one we take first, the object preventing deletion of the referenced row may be not even exist anymore before the protected path is visited. It provides abstractions with the database, in a mostly database agnostic way. The following are 6 code examples for showing how to use django. Take a look at Django m2m examples, specifically the section that says If we delete a Publication, its Articles won’t be able to access it:. The "write protection" message keeps popping up. python] Django 모델에서 on_delete는 무엇을합니까?. CASCADE,当我删除父条目时,它将删除所有相关条目) 我已经搜索了相同的文档,但找不到以下内容:. Often this is used when a user signs up for the first time, needs to reset a password, and so on. Remove an App from your Django project. ForeignKeyField가 바라보는 값이 삭제될 때 삭제가 되지않도록 ProtectedError를 발생시킨다. CASCADE tells Django to cascade the deleting effect i. CASCADE : ForeignKeyField를 포함하는 모델 인스턴스 (row)도 같이 삭제한다. In this tutorial, we're going to work on the organization of tutorials through the use of foreign keys which will allow us to tie certain elements in a database table to another database table's data. django权限不受尊重,django,django-models,django-permissions,Django,Django Models,Django Permissions. The best way to deal with CORS in REST framework is to add the required response headers in middleware. A much better way to do it is to set your foreign keys to have the attribute: on_delete=models. This blog post brings out the possible threats and will act as an entry point for the reader for . How to Implement Multiple User Types with Django. Protect Your Django Web Application From Security Threats. To prevent this we should specify the use of on_delete=models. To delete or remove a file you need to be owner of a file. This article revolves about how one can use Django models to store data in the database conveniently. PROTECT) fk relationship to Category, and Item has a protected fk relationship to Subcategory. recommendations = Recommendation. Giving your users the ability to delete objects from your database is a risky proposition — some types of objects are low risk, but others, . django model - on_delete=models. For real-world applications, it is necessary to filter the queryset to retrieve the relevant results based on the need. CASCADE , that model will be deleted by Django when the parent model is soft deleted. Please refer to the below sample image. In short, Django Models is the SQL of Database one uses with Django. It is a good idea to limit the accessibility of your caching system and database using a. This tutorial builds on Dockerizing Django with Postgres, Gunicorn, and Nginx. We use JWT to handle the authentication hand-off between the front and backends. db import models class Car(models. The more powerful your Django admin is, the safer it should be. Welcome to part 9 of the web development with Python and Django tutorial series. I have something like the code below to save a record in the database: n = MyData. ForeignKey('Manufacturer',on_delete=models. In Django, we can use class-based views to generate forms without defining one in forms. In the current versions this argument is not required, but it will be required in Django 2. PROTECT is the direct opposite of cascade option, here if there is impact on the actual object then all instances of the data on the referenced object are not deleted. However, in regards of using signals for deleting unused media files, the comparison (with advantages and disadvantages) will be left for the end of this article. This is a brief explanation of how authentication is handled in DRF, and how it incorporates CSRF protection. First we need to ensure the django. With this configuration in place, you should be able to send real emails from your Django app. In our case this doesn't make sense - imagine the bank "deleting your money" when you close an account. Click Yes in the warning message window. django models - PageChooserBlockでon_delete = PROTECTを使用できますか? このプロジェクトでは、リンクとして無制限のページを追加できるページが必要です。 コードは次のようになります。. Giving your users the ability to delete objects from your database is a risky proposition — some types of objects are low risk, but others, no matter how much you warn them of the risks of deleting things, will lead to customer requests. This will delete referenced objects as the original object is deleted. ForeignKey (ChatSession, related_name = 'members', on_delete = models. Ideally we should go through all our (non nullable) foreign key fields and check that. can create/update users but cannot delete users). It is implemented via a piece of middleware and can be enabled by using the following code. 单行Django中的查询中介模型,django,Django,我有两个模型。它们是默认的djangousermodel和另一个如下所示的模型: class Recipe(models. ForeignKey (User, on_delete = models. djangoの外部キーで指定するon_deleteのパラメータ(PROTECT, SET_NULL, SET_DEFAULT, RESTRICT)まとめ. Here is an example to delete all posts with future published date value. To create a Django application that performs CRUD operations, follow the following steps. PythonをベースとしたWebフレームワーク『Django』のチュートリアルサイトです。入門から応用まで、レベル別のチュートリアルで学習することができ . Associating Snippets with Users. Serializer): title = serializers. This tutorial shows how to configure Django to load and serve up static and user uploaded media files, public and private, via an Amazon S3 bucket. CASCADE외래키가 바라보는 값이 삭제될때 외래키를 포함하는 모델 인스턴스(row)도 삭제된다. Sometimes open source is better; you get paid for your time to work on the code rather than trying to sell it as a product - which then you have to try and protect. The first step to start using these is to create a new file inside of our register app called forms. 1 command to install Django to your local computer. The fast and maintainable way: _raw_delete () The second fastest way to bulk delete entries in the database with Django is to use the private method _raw_delete. CASCADE) This will cause Car objects to be deleted from the model when its owner deleted from Person model. The default functionality of the argument is shown as following: class Car (model. Here are the different ways to delete objects in Django. Once a site is identified as a Django site, an attacker will most likely try /admin. The following login_required example is one that surprised me a bit because I had not previously seen login_required applied on the parameter to the url function. Next, if you are removing an entire app, you can now remove all the files in that app (models. The author selected the COVID-19 Relief Fund to receive a donation as part of the Write for DOnations program. 삭제하려면 수동으로 참조하는 모든 객체를 삭제해야합니다. Django ships with some nice helpers for doing that, called decorators. Django ORM is one of the best tools of Django and plays very essential role to perform database related tasks. This intermediate-level tutorial is designed for readers who are already familiar with the fundamental design of Django. The idea behind this implementation is: Django wraps the standard database exceptions. Built by experienced developers, Django takes care of much of the hassle of web development, so you can focus on writing your app without needing to reinvent the wheel. PROTECT" setting correctly then the database should merely prevent a model instance from being deleted in situations where that instance is the target of a foreignkey from another model instance. wagtail (project website) is a fantastic Django-based CMS with code that is open source under the BSD 3-Clause "New" or "Revised" License. Protect the intellectual property and the framework's long-term viability. 从上面外键 (ForeignKey)和一对一 (OneToOneField)的参数中可以看出,都有on_delete参数,而 django 升级到2. Our product analyses large datasets every day and as our number of user grew over the last few months, we've had to optimise our algorithm that generates and saves recommendations to our database. on_delete: Record 삭제 시 규칙 - CASCADE: FK로 참조하는 다른 모델의 Record도 삭제 - PROTECT: ProtectedError를 발생시키며 삭제 방지. To make it harder to gain access we can change the “recommended” URL to something harder to guess. hernando county library Likes. How to Delete Objects in Django. CASCADE which, when deleting an object A, it also deletes all related objects B, C, which have A as foreign key. ForeignKeyField (TestModel, on_delete = models. Before beginning, you will need an AWS account. You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each. 110% Complete JWT Authentication with Django & React - 2020. Given below shows the creation of Django on_delete Argument: Select Protect followed by Restrict Editing on the following screen. The next step is to create views (API endpoints) that would be used by our Vue app to manipulate data on the server. Was faced with an optimisation problem today at work. In this tutorial, you protected your system by making the following adjustments in Django Admin: You protected against permission escalation by preventing users from editing their own permissions. Click on Close and save the table in the designer. ) Alternatively, you can use the decorator csrf_protect() on particular views you want to protect (see below). django : 모델에 on_delete 제약 조건이 다른 두 개의 외래 키가있을 때. in trying to delete the album, which is protected because of the related song. Django Rest Framework does provide a ModelViewSet which by default allows handling of POST, PUT, PATCH, and DELETE requests, but since we don't need to handle DELETE requests, we can use the. hard_delete, as above, actually removes the objects from your database, but does this on a QuerySet instead of an individual. > To unsubscribe from this group and stop receiving emails from it, send an email to django-users. One such parameter is the on_delete. Django models' foreign keys require you to set an on_delete function. It also prevents Django from deleting your record just because it deleted an entry on a look-up table. Django admin site will raise exceptions when we try to save objects with non-acceptable values. This was my first time using Python in a production setting and it was a good way to jump straight into the deep end. This is the first in a three-part series that also covers signup and password reset for a complete user authentication flow in your future Django projects. This framework uses a famous tag line: The web framework for. In this tutorial, we will learn how to show custom validation exceptions on Django admin. import bleach from rest_framework import serializers class BookSerializer (serializers. StartUML extension to auto generate Django Models Features. 5 Common Security Issues Facing Millions of Websites on the Internet; Django's Security Patches & Feature Updates; How To Shore Up Your . Django is a popular web framework that allows you to quickly build websites & applications. getenv('SECRET_KEY')) Enter fullscreen mode. A bad way to do it would be to catch the exception in a while loop that keeps deleting protected objects until an exception isn't raised. A Django third-party package named Django-session-csrf is of vital importance in such situations. – Angular Client sends HTTP Requests and retrieve HTTP Responses using HttpClient Module, shows data on the components. 2019年1月23日 by 9nmatsumoto Leave a Comment. But you can trigger this when you just submit the intermediate page that states that you cannot delete protected item. forms import UserCreationForm from django. Remove the remnant ContentTypes. Something like: class ContentItemOrderPostAdmin(admin. The default is CASCADE - when the user is deleted the related account is deleted as well. If authentication_classes isn't defined for a view, or it's an empty list, SessionAuthentication is run by default. And secondly, if I understand the "models. ForeignKey ('Person', on_delete=models. PROTECT SET_NULL:外键会被设为NULL,前提是字段允许null和blank on_delete=models. If you have sufficient rights, you can remove a file. Django database integrity: ForeignKey on_delete options. Adding endpoints for our User models. Django models simplify the tasks and organize tables into models. def delete(self, request, image_id, format=None): PROTECT, null=True, blank=True). PROTECT) When I delete an order related to a customer it will. Wagtail does not allow simple database CASCADE because it will corrupt its tree storage. The following are 30 code examples for showing how to use django. models import User class RegisterForm(UserCreationForm): email = forms. CASCADE : ForeignKeyField를 포함하는 모델 인스턴스(row)도 같이 삭제한다. This is the application architecture we’re gonna build: – Django exports REST Apis using Django Rest Framework & interacts with Database using Django Model. The PROTECT argument of the ForeignKey on_delete option prevents the referenced object from being deleted if it already has an object . get_fields (): try : # check if there is a relationship with at least one related object related = rel. Authentication and CSRF Protection in Django Rest Framework. A skilled developer, an attacker or even a tech savvy user can identify a Django site by looking at things. Create a new secret, django_settings, with the value of the. A user added to a Group with a set. What this line does is make the os (operating system) get the. Django는 SQL 제약 조건인 ON DELETE CASCADE의 동작을 에뮬레이션 하고 ForeignKey를 포함한 객체를 삭제한다. It assumes you understand how to containerize a Django app along with Postgres, Nginx, and Gunicorn. From the terminal you can run: sudo rm -r /my/locked/directory as the instruction will prompt any warning message during the execution and you will be able to check what are you deleting. PROTECT, 어떠한 요소를 삭제 할 때 그 삭제하는 대상과 관계가 있는 요소가 함께 삭제되지 않도록 . - Angular Client sends HTTP Requests and retrieve HTTP Responses using HttpClient Module, shows data on the components. The pieces: delete — bulk deleting a QuerySet bypasses an individual object's delete method, which is why this is needed here as well. The cross-site request forgery (CSRF) is one of them. That makes it easy to deal with database exceptions in Python at a certain level. PROTECT (see docs here) where it makes sense. Sometimes, we need a bit more control. This is the application architecture we're gonna build: - Django exports REST Apis using Django Rest Framework & interacts with Database using Django Model. ] 을 유지하여 ForeignKeyField가 바라보는 값이 삭제될 때 해당 요소를 처리하는 방법을 지정 해 준다. Before we jump in, here are the docs on Django QuerySets. models import ContentType # List of deleted apps DEL_APPS = ["app-you-deleted", "second-app. on_deleteというのは、modelのForeignKeyで外部キーを作成する際に指定し、接続先のテーブルのレコードが削除された場合に、 接続元の. 不少小伙伴在做migration的时候发现,现在on_delete以及不再支持默认,必须要显式申明。on_delete有以下选项: CASCADE:联级删除 on_delete=models. To associate an image to a model in Django, we need to define an ImageField in the corresponding model, setting some optional configurations:. staticfiles is added as a part of INSTALLED APPS in SETTINGS. Das PROTECT-Argument der Option ForeignKey on_delete verhindert, dass das referenzierte Objekt gelöscht wird, wenn . Just tested with current code, and I cannot reproduce your bug. Django on_delete · CASCADE – the object that references the deleted object gets deleted itself · PROTECT – Prevents the deletion of the referenced object by . Auto-generate Django Model Class. Step 1: pip install pipenv pipenv shell pipenv install django. When you have to choose the permissions of the group, the box will show permissions that refer to the deleted models. Form): captcha = ReCaptchaField() That's it! Bonus: Enable submit button after captcha has been processed. djangoのmodelで使用するon_deleteってなんぞ?. django model get field verbose name. There is a related issue: #1602, but it's. SQL (Structured Query Language) is complex and involves a lot of different queries for creating, deleting, updating or any other stuff related to database. Modeling polymorphism in relational databases is a challenging task. In this article I present 5 ways to protect the Django Admin from human errors and attackers. We have used Django signals before and wrote about it on this blog. Recently I faced a problem when restricting access to a user based on the group that the user belongs to. This was followed by a prompt stating that the database contained non-null value types but did not have a default value set. PROTECT : Forbid the deletion of the referenced object. To delete it you will have to delete all objects that reference. py, you will retrieve the key as follows: # settings. Want to know how to protect source code? > You received this message because you are subscribed to the Google Groups "Django users" group. When trying to delete a Category that has Subcategories, the Django admin displays a readable, understandable message explaining that the model instance has related models, so it can't be deleted. Vault supports dynamic secrets, versioning, audit logs, and extensibility via identity plugins. All the static files will be served to the webpage using a url, and this url will have this /static/ appended to it. In most cases, it's redundant to have two possible values for "no data;" the Django convention is to use the empty string, not NULL. ManyToManyField is a subclass of django. py and write the following: from django. django rest framework urls django rest framework urls. This is true for ForeignKey, OneToOne, and ManyToMany fields. Generally, each model maps to a single database table. PROTECT) # Disallow lookup deletion & do not delete this rec. The framework includes built-in models for Users and Groups (a generic way of applying permissions to more than one user at a time), permissions. ; Auto-generate attributes with the suitable type, using standard Djando Model Field, provided by Django ORM. Many popular security attacks exist on the web. A session is a mechanism to store information on the server side during the interaction with the web application. 3 for one of my projects and I need to get the ID of a record just saved in the database. Django : what does on_delete=models. Django also offers a variety of security-oriented settings that can help you seamlessly prepare your project for production. 我对Django非常熟悉,但是最近发现模型中存在on_delete=models. Form): captcha = ReCaptchaField() That’s it! Bonus: Enable submit button after captcha has been processed. signals module of the Django project. pre_delete is a callable within the django. on_delete method is used to tell Django what behavior to adopt when the referenced object is deleted. WAS IST Modelle schützen in Django? SCHÜTZEN. The developer needs to be sure that all unsafe views (POST, UPDATE, PUT, Delete) are protected by the builtin Django CSRF protection because as I mentioned above DRF disables them by default. Developing a Django application can be a quick and clean experience, because its approach is flexible and scalable. 0使用外键 (ForeignKey)和一对一 (OneToOneField)的时候,必须添加on_delete参数,不然就会报错。. Next, we need to ensure the static url is being set to '/static/'. They've been building Bento, a program analysis toolkit that can find . If I wanted to do this in the normal Django admin I would make use of an inlines to specify prerequisites. ForeignKey(Album, related_name='tracks', on_delete=models. any attempt to delete an Album record will be blocked) on_delete = models. ForeignKey(Cliente,related_name="cliente",on_delete=models. in the client-side the developer should take care of: In the client-side, every request will contain refresh token in the cookies automatically (be sure. Those flags are used in the Django Admin app, the is_staff flag designates if the user can log in the Django Admin pages. The warning gives the following hint: Set on_delete=models. Adding the decorator to a view limits access only to the logged in users. The following are 14 code examples for showing how to use django. A Django model is the built-in feature that Django uses to create tables, their fields, and various constraints. CASCADE PROTECT:不可删除,抛出ProtectedError错误 on_delete=models. PROTECT (collector, fields, sub_objs, using)). 6x环境 练习Django中的一对多关系,使用Foreign关键字创建多对一的关系,Foreign(外键所在类对象的名字) 比如:书籍和作者的关系 一位作者可以创作多本书籍,models. Hi all, I appreciate this question does get asked, however, I feel like this is a bit different to the usual statics not being found question. Permissions are used to grant or deny access for different classes of users to different parts of the API. The relevant code is django/db/models/deletion. A way to persist in Django the order of a list of items, A way to allow a user to reorder an HTML list via drag and drop, A way to detect changes and save the new order into Django. Here's a more concrete example. CharField(max_length=100) duration = models. Foreign Keys On_Delete Option In Django Models. Please remove write-protected or use another disk to save. Here, we set the members field to use the CheckboxSelectMultiple widget instead of the default multiple choice field. models import signals, sql class ProtectedError(IntegrityError): def __init__(self, msg, protected_objects): self. Add a on_delete RESTRICT handler to allow cascading. Blog; Topics; Subscribe; Fastest way to bulk delete in Django published: 22 Aug 2017. It is not specific to django, this is an SQL standard. Contribute to aprilkrg/django_code_along development by creating an account on GitHub. Django OAuth Toolkit provides a set of generic class based view you can use to add OAuth behaviour to your views. a toolset for creating/deleting/activating/etc. The file should contain the following: from django import forms from django. At delete, the Django collector crawls the relationships and buckets each object found into different lists depending on the on_delete configuration for that specific relationship. 0以降のバージョンで、モデルを作成する際に、 on_deleteというパラメータを指定することが必須になった。. Django Login and Logout Tutorial. That's not the default behaviour. Each Snapshot will have a list of all the records affected by the delete that created it. This is a Django security requirement, designed to prevent HTTP Host header attacks. display data from database in django. What is Soft Deletion? Sometimes, you want to delete something from your database without Tagged with python, django. Django emulates the behavior of the SQL constraint ON DELETE CASCADE and also deletes the object containing the ForeignKey.