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Django along with Python is one of the most in-demand skills and surely amongst some of the trickiest ones. So if you want to prepare yourself to perform the best in the upcoming Django interview, here are the top 50 commonly asked Django Interview Questions and Answers.
Q1. What is the difference between Flask and Django?
Q2. What is Django?
Q3. Do you know any companies that use Django?
Q4. What are the features of Django?
Q5. How do you check for the version of Django installed on your system?
Q6. What are the advantages of using Django?
Q7. Explain Django’s architecture.
Q8. Give a brief about the Django admin.
Q9. How do you connect your Django Project to the database?
Q10. What are the various files that are created when you create a Django Project? Explain briefly.
|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|
Django is a web development framework that was developed in a fast-paced newsroom. It is a free and open-source framework that was named after Django Reinhardt who was a jazz guitarist from the 1930s. Django is maintained by a non-profit organization called the Django Software Foundation. The main goal of Django is to enable Web Development quickly and with ease.
Some of the companies that make use of Django are Instagram, DISCUS, Mozilla Firefox, YouTube, Pinterest, Reddit, etc.
To check for the version of Django installed on your system, you can open the command prompt and enter the following command:
You can also try to import Django and use the get_version() method as follows:
import django print(django.get_version())
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.
To display the usage information and the list of the commands provided by each application
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
Creating new migrations based on the changes made in models
Synchronizing the database state with the current set of models and migrations
Starting the development server
Sending a test email in order to confirm the email sending through Django is working
To start the Python interactive interpreter
To show all the migrations in your project
Django comes with a default database which is SQLite. To connect your project to this database, use the following commands:
When you create a project using the startproject command, the following files will be created:
A command-line utility that allows you to interact with your Django project
An empty file that tells Python that the current directory should be considered as a Python package
Consists of the settings for the current project
Contains the URL’s for the current project
This is an entry-point for the web servers to serve the project you have created
Models are a single and definitive source for information about your data. It consists of all the essential fields and behaviors of the data you have stored. Often, each model will map to a single specific database table.
In Django, models serve as the abstraction layer that is used for structuring and manipulating your data. Django models are a subclass of the django.db.models.Model class and the attributes in the models represent database fields.
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 HttpResponse 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.
Django’s 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.
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.
Django has three possible inheritance styles:
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
Used when you have to subclass an existing model and want each
model to have its own database table
Used if you only want to modify the Python-level behavior of a model, without changing the ‘models’ fields in any way
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:
Sent before or after a model’s save() method is called
Sent before or after a model’s delete() method or queryset’s delete() method is called
Sent when Django starts or finishes an HTTP request
‘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.
To create a Django project, cd into the directory where you would like to create your project and type the following command:
NOTE: Here, xyz is the name of the project. You can give any name that you desire.
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.
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.
Context in Django is a dictionary mapping template variable name given to Python objects. This is the conventional name, but you can give any other name of your choice if you wish to do it.
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.
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:
Memory-based cache server which is the fastest and most efficient
Cache values are stored as separate files in a serialized order
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
Cache data will be stored in the database and works very well if you have a fast and well-indexed database server
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.
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.
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.
In order to view all the items from your database, you can make use of the ‘all()’ function in your interactive shell as follows:
To filter out some element from your database, you either use the get() method or the filter method as follows:
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:
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.
In order to make use of file-based sessions, you will need to set the SESSION_ENGINE setting to “django.contrib.sessions.backends.
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.
Django uses its own exceptions as well as those present in Python. Django core exceptions are present in django.core.exceptions class some of which are mentioned in the table below:
Raised when you try to use your models before the app loading process (initializes the ORM) is completed.
This is the base class for DoesNotExist exceptions
This exception may be raised if a query won’t return any result
This exception is raised by a model’s _meta.get_field() function in case the requested field does not exist
This is raised by a query if multiple objects are returned and only one object was expected
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.
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.
Django is not a CMS (content-management-system) . It is just a Web framework, a tool that allows you to build websites.
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.
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.
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.
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.
from django.http import HttpResponse def hello_world(request): html = " <h1>Hello World!</h1> " return HttpResponse(html)
Q42. 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.
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.
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().
Inconsistent row counts are a result of missing Foreign Key values or if the Foreign Key field is set to null=False. If the ForeignKey points 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.
No. Django only supports single-column Primary Keys.
First, make sure that your DEBUG setting is set to True. Then, type the following commands:
from django.db import connection connection.queries
No. The model/ database layer is actually decoupled from the rest of the framework.
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.
With this, we have reached the end of this article on Django Interview Questions. I hope you are clear with all that has been shared with you in this article. Make sure you practice as much as possible and revert your experience.
Got a question for us? Please mention it in the comments section of this “Django Interview Questions” blog and we will get back to you as soon as possible.
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