Django Interview Questions

1. What is the difference between Flask and Django?

Comparison Factor	Django	Flask
Project Type	Supports large projects	Built for smaller projects
Templates, Admin and ORM	Built-in	Requires installation
Ease of Learning	Requires more learning and practice	Easy to learn
Flexibility	Allows complete web development without the need for third-party tools	More flexible as the user can select any third-party tools according to their choice and requirements
Visual Debugging	Does not support Visual Debug	Supports Visual Debug
Type of framework	Batteries included	Simple, lightweight
Bootstrapping-tool	Built-it	Not available

2. What is Django?

Django is a free and open-source web framework written in Python. It is designed to help developers build web applications quickly and easily. Django follows the “batteries-included” philosophy, meaning that it comes with a wide range of tools and features that allow developers to build almost any type of web application without having to install additional libraries.

Some of the key features of Django include:

• A powerful ORM (Object-Relational Mapper) for interacting with databases.
• A template engine for creating HTML, XML, or other markup formats.
• A form handling library for validating and processing user input.
• A caching system for improving the performance of dynamic websites.
• An authentication and authorization system for managing user accounts and permissions.

Django is known for its simplicity, flexibility, and scalability. It has a large and active community of users and developers, and is used by many well-known websites, including Instagram and Pinterest.

3. Name some companies that make use of Django?

There are many well-known companies that make use of Django in their web applications and websites. Some examples include:

• Instagram: Instagram is a popular photo and video sharing platform that was built using Django.
• Pinterest: Pinterest is a social media platform that allows users to discover and save ideas for various topics. It uses Django as its backend framework.
• Disqus: Disqus is a popular commenting platform used by websites and blogs all over the world. It is built using Django.
• Mozilla: The Mozilla Foundation, the non-profit organization behind the Firefox web browser, uses Django to power several of its websites and applications.
• The Washington Post: The Washington Post, a major newspaper based in the United States, uses Django to power its online news platform.

These are just a few examples, and there are many other companies and organizations that use Django in their web applications. Django is a popular choice for web development due to its flexibility, scalability, and large ecosystem of libraries and tools.

4. What are the features of Django? 

• SEO Optimized
• Extremely fast
• Fully loaded framework that comes along with authentications, content administrations, RSS feeds, etc
• Very secure thereby helping developers avoid common security mistakes such as cross-site request forgery (csrf), clickjacking, cross-site scripting, etc
• It is exceptionally scalable which in turn helps meet the heaviest traffic demands
• Immensely versatile which allows you to develop any kind of websites

5. How do you check for the version of Django installed on your system?

To check the version of Django installed on your system, you can use the following steps:

1. Open a terminal or command prompt window.
2. Activate your virtual environment, if you are using one.
3. Type the following command and press Enter:

Copy codepython -m django --version

This will print the version number of Django that is currently installed on your system. If you have multiple versions of Django installed, this command will show the version that is currently being used.

Alternatively, you can check the version of Django by opening a Python interpreter and typing the following:

Copy codeimport django
print(django.get_version())

This will also print the version number of Django that is currently installed on your system.

If you are using Django in a project and have it listed in your requirements.txt or Pipfile, you can also check the version by looking at the file. The version will be listed next to the package name, like this: django==3.1.5.

6. What are the advantages of using Django?

• Django’s stack is loosely coupled with tight cohesion
• The Django apps make use of very less codehttps://datavalley.ai/interview-questions-and-answers-on-continuous-feedback-experimentation/
• Allows quick development of websites
• Follows the DRY or the Don’t Repeat Yourself Principle which means, one concept or a piece of data should live in just one place
• Consistent at low as well as high levels
• Behaviors are not implicitly assumed, they are rather explicitly specified
• SQL statements are not executed too many times and are optimized internally
• Can easily drop into raw SQL whenever required
• Flexibility while using URL’s

7. Explain Django architecture.

Django follows the MVT or Model View Template architecture whcih is based on the MVC or Model View Controller architecture. The main difference between these two is that Django itself takes care of the controller part.

According to Django, the ‘view’ basically describes the data presented to the user. It does not deal with how the data looks but rather what the data actually is. Views are basically callback functions for the specified URL’s and these callback functions describe which data is presented.

The ‘templates’ on the other hand deal with the presentation of data, thereby, separating the content from its presentation. In Django, views delegate to the templates to present the data.

The ‘controller’ here is Django itself which sends the request to the appropriate view in accordance with the specified URL. This is why Django is referred to as MTV rather than MVC architecture.

8. Give a brief about ‘django-admin’.

django-admin is the command-line utility of Django for administrative tasks. Using the django-admin you can perform a number of tasks some of which are listed out in the following table:

Task	Command
To display the usage information and the list of the commands provided by each application	django-admin help
To display the list of available commands	django-admin help –command
To display the description of a given command and the list of its available options	django-admin help <command>
Determining the version of Django	django-admin version
Creating new migrations based on the changes made in models	django-admin makemigrations
Synchronizing the database state with the current set of models and migrations	django-admin migrate
Starting the development server	django-admin runserver
Sending a test email in order to confirm the email sending through Django is working	django-admin sendtestemail
To start the Python interactive interpreter	django-admin shell
To show all the migrations in your project	django-admin showmigrations

9. How do you connect your Django project to the database?

Django comes with a default database which is SQLite. To connect your project to this database, use the following commands:

1. python manage.py migrate (migrate command looks at the INSTALLED_APPS settings and creates database tables accordingly)
2. python manage.py makemigrations (tells Django you have created/ changed your models)
3. python manage.py sqlmigrate <name of the app followed by the generated id> (sqlmigrate takes the migration names and returns their SQL)

10. What are the various files that are created when you create a Django Project? Explain briefly.

When you create a project using the startproject command, the following files will be created:

File Name	Description
manage.py	A command-line utility that allows you to interact with your Django project
__init__.py	An empty file that tells Python that the current directory should be considered as a Python package
settings.py	Consists of the settings for the current project
urls.py	Contains the URL’s for the current project
wsgi.py	This is an entry-point for the web servers to serve the project you have created

Django Interview Questions

11. What are ‘Models’?

In the context of Django, a modelhttps://datavalley.ai/aws-certified-data-analytics-specialty-aws-data/ is a Python class that defines the structure and behavior of data in a web application. Models are used to represent database tables and the relationships between them.

Models are defined in Django using Python classes that subclass django.db.models.Model. Each model class defines a set of fields, which represent the columns in the database table. The fields are defined as class variables, and each field is an instance of a field type (such as CharField, IntegerField, etc.).

For example, here is a simple model that defines a database table for storing information about books:

Copy codefrom django.db import models

class Book(models.Model):
    title = models.CharField(max_length=200)
    author = models.CharField(max_length=200)
    published_date = models.DateField()

This model defines a database table with three columns: title, author, and published_date. The title and author fields are both CharFields, which are used to store character data (such as strings), and the published_date field is a DateField, which is used to store date values.

Models in Django also provide a number of other features, such as support for relationships between models (e.g., one-to-one, many-to-one, etc.), database migrations, and querying the database using the Django ORM (Object-Relational Mapper).

12. What are ‘views’?

Django views serve the purpose of encapsulation. They encapsulate the logic liable for processing a user’s request and for returning

the response back to the user. Views in Django either return an HttpResponsehttps://datavalley.ai/category/cloud-computing/ or raise an exception such as Http404. HttpResponse contains the objects that consist of the content that is to be rendered to the user. Views can also be used to perform tasks such as read records from the database, delegate to the templates, generate a PDF file, etc.

13. What are ‘templates’?

Django’shttps://datavalley.ai/python-programming-facts-python-interesting-fact/ template layer renders the information to be presented to the user in a designer-friendly format. Using templates, you can generate HTML dynamically. The HTML consists of both static as well as dynamic parts of the content. You can have any number of templates depending on the requirement of your project. It is also fine to have none of them.

Django has its own template system called the Django template language (DTL). Regardless of the backend, you can also load and render templates using Django’s standard admin.

14. What is the difference between a Project and an App?

An app is basically a Web Application that is created to do something for example, a database of employee records. A project, on the other hand, is a collection of apps of some particular website. Therefore, a single project can consist of ‘n’ number of apps and a single app can be in multiple projects.

15. What are the different inheritance styles in Django?

Django has three possible inheritance styles:

Inheritance style	Description
Abstract base classes	Used when you want to use the parent class to hold information that you don’t want to type for each child model. Here, the parent class is never used in solitude
Multi-table inheritance	Used when you have to subclass an existing model and want eachmodel to have its own database table
Proxy models	Used if you only want to modify the Python-level behavior of a model, without changing the ‘models’ fields in any way

16. What are static files?

In Django, static files refer to files that are not generated dynamically by the web application, but are instead served as-is to the client. These can include things like images, CSS files, JavaScript files, and other types of media.

In Django, static files are typically stored in a special directory within the project structure called static. This directory can be located at the root level of the project, or it can be nested inside one of the Django app directories.

To use static files in a Django application, you need to set up a static file server. This can be done by configuring the Django STATICFILES_DIRS setting, which specifies the locations of the static files. Django also provides a static template tag, which can be used in templates to refer to static files.

For example, to include an image in a template, you might use the following code:

Copy code<img src="{% static 'images/logo.png' %}" alt="Logo">

This will include the logo.png file from the images directory within the static directory. When the template is rendered, the static template tag will be replaced with the URL of the static file, which will be served by the static file server.

Overall, static files are an important part of any web application, and Django provides a convenient and flexible way to manage and serve them.

17. What are ‘signals’?

Django consists of a signal dispatcher that helps allow decoupled applications to get notified when actions occur elsewhere in the framework. Django provides a set of built-in signals that basically allow senders to notify a set of receivers when some action is executed. Some of the signals are as follows:

Signal	Description
django.db.models.signals.pre_savedjango.db.models.signals.post_save	Sent before or after a model’s save() method is called
django.db.models.signals.pre_deletedjango.db.models.signals.post_delete	Sent before or after a model’s delete() method or queryset’s delete() method is called
django.db.models.signals.m2m_changed	Sent when Django starts or finishes an HTTP request

18. Briefly explain Django Field Class.

‘Field’ is basically an abstract class that actually represents a column in the database table. The Field class, is in turn, a subclass of  RegisterLookupMixin.

In Django, these fields are used to create database tables (db_type()) which are used to map Python types to the database using get_prep_value() and vice versa using from_db_value() method. Therefore, fields are fundamental pieces in different Django APIs such as models and querysets.

19. How to do you create a Django project?

To create a new Django project, you will need to have the Django package installed on your system. You can install Django using pip, the Python package manager, by running the following command:

Copy codepip install django

Once Django is installed, you can create a new project using the django-admin startproject command. Open a terminal or command prompt window, navigate to the directory where you want to create the project, and enter the following command:

Copy codedjango-admin startproject myproject

Replace myproject with the desired name for your project. This will create a new directory with the same name as your project, and generate the basic files and directories needed for a Django project inside it.

The directory structure of the new project will look something like this:

Copy codemyproject/
├── manage.py
└── myproject/
    ├── __init__.py
    ├── asgi.py
    ├── settings.py
    ├── urls.py
    └── wsgi.py

The manage.py script is used to manage the Django project, and the myproject directory contains the main Django settings, URL configurations, and WSGI application.

Once the project is created, you can start the development server by running the following command from the root of the project directory:

Copy codepython manage.py runserver

This will start the development server at http://127.0.0.1:8000/. You can visit this URL in your web browser to see the default Django “Welcome to Django” page.

You can then start building your web application by defining models, creating views and templates, and configuring URLs.

Django Interview Questions

20. What is mixin?

Mixin is a type of multiple inheritance wherein you can combine behaviors and attributes of more than one parent class. Mixins provide an excellent way to reuse code from multiple classes.

For example, generic class-based views consist of a mixin called TemplateResponseMixin whose purpose is to define render_to_response() method. When this is combined with a class present in the View, the result will be a TemplateView class.

One drawback of using these mixins is that it becomes difficult to analyze what a child class is doing and which methods to override in case of its code being too scattered between multiple classes.

21. What are ‘sessions’?

Sessions are fully supported in Django. Using the session framework, you can easily store and retrieve arbitrary data based on the per-site-visitors.

This framework basically stores data on the server-side and takes care of sending and receiving cookies. These cookies consist of a session ID but not the actual data itself unless you explicitly use a cookie-based backend.

22. What do you mean by context?

In Django, the term “context” refers to a dictionary-like object that is used to pass data from the view to the template in a web application. The context is populated with data by the view, and the template can then use the context to access and display this data.

For example, consider a view that displays a list of articles from a database. The view might retrieve the articles from the database and store them in a context variable called articles. The view could then render a template that loops through the articles and displays them to the user.

Here is an example of a view function that populates the context with data:

Copy codedef article_list(request):
    articles = Article.objects.all()
    context = {'articles': articles}
    return render(request, 'articles.html', context)

And here is an example of a template that uses the context data to display a list of articles:

Copy code{% for article in articles %}
  <h2>{{ article.title }}</h2>
  <p>{{ article.body }}</p>
{% endfor %}

In this example, the view retrieves a list of articles from the database and stores them in the context variable articles. The template then uses the for loop to iterate over the articles and display their title and body attributes.

Overall, the context is an important feature of Django that allows views to pass data to templates and enables templates to access and display that data.

23. When can you use iterators in Django ORM?

Iterators in Python are basically containers that consist of a countable number of elements. Any object that is an iterator implements two methods which are, the __init__() and the __next__()  methods.

When you are making use of iterators in Django, the best situation to do it is when you have to process results that will require a large amount of memory space. To do this, you can make use of the iterator() method which basically evaluates a QuerySet and returns the corresponding iterator over the results.

24. Explain the caching strategies of Django?

Caching basically means to save the output of an expensive calculation in order to avoid performing the same calculation again. Django provides a robust cache system which in turn helps you save dynamic web pages so that they don’t have to be evaluated over and over again for each request. Some of the caching strategies of Django are listed down in the following table:

Strategy	Description
Memcached	Memory-based cache server which is the fastest and most efficient
Filesystem caching	Cache values are stored as separate files in a serialized order
Local-memory caching	This is actually the default cache in case you have not specified any other. This type of cache is per-process and thread-safe as well
Database caching	Cache data will be stored in the database and works very well if you have a fast and well-indexed database server

25. Explain the use of Middlewares in Django.

You may come across numerous Django Interview Questions, where you will find this question. Middleware is a framework that is light and low-level plugin system for altering Django’s input and output globally. It is basically a framework of hooks into the request/ response processing of Django. Each component in middleware has some particular task.

For example, the AuthenticationMiddleware is used to associate users with requests using sessions. Django provides many other middlewares such as cache middleware to enable site-wide cache, common middleware that performs many tasks such as forbidding access to user agents, URL rewriting, etc, GZip middleware which is used to compress the content for browsers, etc.

26. What is the significance of manage.py file in Django?

The manage.py file is automatically generated whenever you create a project. This is basically a command-line utility that helps you to interact with your Django project in various ways.

It does the same things as django-admin but along with that, it also sets the DJANGO_SETTINGS_MODULE environment variable in order to point to your project’s settings. Usually, it is better to make use of manage.py rather than the django-admin in case you are working on a single project.

27. Explain the use of ‘migrate’ command in Django?

In Django, migrations are used to propagate changes made to the models. The migrate command is basically used to apply or unapply migrations changes made to the models.

This command basically synchronizes the current set of models and migrations with the database state. You can use this command with or without parameters. In case you do not specify any parameter, all apps will have all their migrations running.

28. How to view and filter items from the database?

In order to view all the items from your database, you can make use of the ‘all()’ function in your interactive shell as follows:

• XYZ.objects.all()     where XYZ is some class that you have created in your models

To filter out some element from your database, you either use the get() method or the filter method as follows:

• XYZ.objects.filter(pk=1)
• XYZ.objects.get(id=1)

29. Explain how a request is processed in Django?

In case some user requests a page from some Django powered site, the system follows an algorithm that determines which Python code needs to be executed. Here are the steps that sum up the algorithm:

1. Django first determines which root URLconf or URL configuration module is to be used
2. Then, that particular Python module is loaded and then Django looks for the variable urlpatterns
3. These URL patterns are then run by Django, and it stops at the first match of the requested URL
4. Once that is done, the Django then imports and calls the given view
5. In case none of the URLs match the requested URL, Django invokes an error-handling view

Django Interview Questions

30. How did Django come into existence?

Django basically grew from a very practical need. World Online developers namely Adrian Holovaty and Simon Willison started using Python to develop its websites. As they went on building intensive, richly interactive sites, they began to pull out a generic Web development framework that allowed them to build Web applications more and more quickly. In summer 2005, World Online decided to open-source the resulting software, which is, Django.

31. How to use file-based sessions?

In Django, file-based sessions allow you to store session data on the server as files, rather than in a database or other storage backend. To use file-based sessions, you will need to set the SESSION_ENGINE setting in your Django settings file to "django.contrib.sessions.backends.file".

For example, to configure file-based sessions in Django, you might add the following lines to your settings file:

Copy codeSESSION_ENGINE = "django.contrib.sessions.backends.file"
SESSION_FILE_PATH = "/path/to/session/files"

The SESSION_FILE_PATH setting specifies the directory where the session files will be stored. You will need to create this directory and make sure it is writable by the Django process.

Once file-based sessions are configured, you can use the request.session object in your views to access and manipulate session data. For example, to store data in the session, you can use the following code:

Copy coderequest.session['key'] = 'value'

To retrieve data from the session, you can use the following code:

Copy codevalue = request.session['key']

You can also use the request.session object to delete data from the session or to clear the entire session.

Overall, file-based sessions are a simple and lightweight way to store session data in Django. They may not be suitable for large or high-traffic applications, but can be a good choice for smaller or simpler projects.

32. Explain the Django URLs in brief?

Django allows you to design your own URLs however you like. The aim is to maintain a clean URL scheme without any framework limitations. In order to create URLs for your app, you will need to create a Python module informally called the URLconf or URL configuration which is pure Python code and is also a mapping between the URL path expressions to the Python methods.

The length of this mapping can be as long or short as required and can also reference other mappings. When processing a request, the requested URL is matched with the URLs present in the urls.py file and the corresponding view is retrieved. For more details about this, you can refer to the answer to Q29.

33. Give the exception classes present in Django.

Django uses its own exceptions as well as those present in Python. Django core exceptions are present in django.core.exceptionsclass some of which are mentioned in the table below:

Exception	Description
AppRegistryNotReady	Raised when you try to use your models before the app loading process (initializes the ORM) is completed.
ObjectDoesNotExist	This is the base class for DoesNotExist exceptions
EmptyResultSet	This exception may be raised if a query won’t return any result
FieldDoesNotExist	This exception is raised by a model’s _meta.get_field() function in case the requested field does not exist
MultipleObjectsReturned	This is raised by a query if multiple objects are returned and only one object was expected

34. Is Django stable?

Yes, Django is quite stable. Many companies like Instagram, Discus, Pinterest, and Mozilla have been using Django for a duration of many years now. Not just this, Websites that are built using Django have weathered traffic spikes of over 50 thousand hits per second.

Django Interview Questions

35. Does the Django framework scale?

Yes. Hardware is much cheaper when compared to the development time and this is why Django is designed to make full use of any amount of hardware that you can provide it. Django makes use of a “shared-nothing” architecture meaning you can add hardware at any level i.e database servers, caching servers or Web/ application servers.

36. Is Django a CMS?

Django is not a CMS (content-management-system) . It is just a Web framework, a tool that allows you to build websites.

37. What Python version should be used with Django?

The following table gives you the details of the versions of Python that you can use for Django:

Python 3 is actually the most recommended because it is fast, has more features and is better supported. In the case of Python 2.7, Django 1.1 can be used along with it but only till the year 2020.

38. Does Django support NoSQL?

NoSQL basically stands for “not only SQL”. This is considered as an alternative to the traditional RDBMS or the relational Databases.  Officially, Django does not support NoSQL databases. However, there are third-party projects, such as Django non-rel, that allow NoSQL functionality in Django. Currently, you can use MongoDB and Google App Engine.

39. How can you customize the functionality of the Django admin interface?

There are a number of ways to do this. You can piggyback on top of an add/ change form that is automatically generated by Django, you can add JavaScript modules using the js parameter. This parameter is basically a list of URLs that point to the JavaScript modules that are to be included in your project within a <script> tag. In case you want to do more rather than just playing around with from, you can exclusively write views for the admin.

40. Is Django better than Flask?

Django is a framework that allows you to build large projects. On the other hand, Flask is used to build smaller websites but flask is much easier to learn and use compared to Django. Django is a full-fledged framework and no third-party packages are required. Flask is more of a lightweight framework that allows you to install third-party tools as and how you like. So, the answer to this question basically depends on the user’s need and in case the need is very heavy, the answer is definitely, Django.

Django Interview Questions

41. Give an example of a Django view.

A view in Django either returns an HttpResponse or raises an exception such as Http404. HttpResponse contains the objects that consist of the content that is to be rendered to the user.

EXAMPLE:

1234567

from django.http import HttpResponsedef hello_world(request):    html = "<h1>Hello World!</h1>"    return HttpResponse(html)

42. What should be done in case you get a message saying “Please enter the correct username and password” even after entering the right details to log in to the admin section?

In case you have entered the right details and still not able to login to the admin site, cross verify if the user account has is_active and is_staff attributes set to True. The admin site allows only those users for whom these values are set to True.

43. What should be done in case you are not able to log in even after entering the right details and you get no error message?

In this case, the login cookie is not being set rightly. This happens if the domain of the cookie sent out by Django does not match the domain in your browser. For this, you must change the SESSION_COOKIE_DOMAIN setting to match that of your browser.

44. How can you limit admin access so that the objects can only be edited by those users who have created them?

Django’s ModelAdmin class provides customization hooks using which, you can control the visibility and editability of objects in the admin. To do this, you can use the get_queryset() and has_change_permission().

45. What to do when you don’t see all objects appearing on the admin site?

Inconsistent row counts are a result of missing Foreign Key values or if the Foreign Key field is set to null=False. If the ForeignKeypoints to a record that does not exist and if that foreign is present in the list_display method, the record will not be shown the admin changelist.

46. What do you mean by the csrf_token?

The csrf_token is used for protection against Cross-Site Request Forgeries. This kind of attack takes place when a malicious website consists of a link, some JavaScript or a form whose aim is to perform some action on your website by using the login credentials of a genuine user.

47. Does Django support multiple-column Primary Keys?

No. Django only supports single-column Primary Keys.

48. How can you see the raw SQL queries that Django is running?

First, make sure that your DEBUG setting is set to True. Then, type the following commands:

12	fromdjango.db importconnectionconnection.queries

49. Is it mandatory to use the model/ database layer?

No. The model/ database layer is actually decoupled from the rest of the framework.

50. How to make a variable available to all the templates?

You can make use of the RequestContext in case all your templates require the same objects, such as, in the case of menus. This method takes an HttpRequest as its first parameter and it automatically populates the context with a few variables, according to the engine’s

context_processors configuration option.