Latest Django Interview Questions

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Django interview questions

A mixin is a special kind of multiple inheritances in Python. There are two main situations where mixins are used:

  • You want to provide a lot of optional features for a class.
  • You want to use one particular feature in a lot of different classes.

Read More from https://stackoverflow.com/questions/533631/what-is-a-mixin-and-why-are-they-useful

Yes, Django follows Model-View-Controller (MVC) architectural pattern.

Few caching strategies that are available in Django are as follows:

  • File system caching
  • In-memory caching
  • Using Memcached
  • Database caching

In Django whenever a request is made by a user, it goes through the following steps:

  • Django determines the root URLconf module to use. Ordinarily, this is the value of the ROOT_URLCONF setting, but if the incoming HttpRequest object has a urlconf attribute (set by middleware), its value will be used in place of the ROOT_URLCONF setting.
  • Django loads that Python module and looks for the variable urlpatterns. This should be a Python list of django.urls.path() and/or django.urls.re_path() instances.
  • Django runs through each URL pattern, in order, and stops at the first one that matches the requested URL.
  • Once one of the URL patterns matches, Django imports and calls the given view, which is a simple Python function (or a class-based view). The view gets passed the following arguments:
    • An instance of HttpRequest.
    • If the matched URL pattern returned no named groups, then the matches from the regular expression are provided as positional arguments.
    • The keyword arguments are made up of any named parts matched by the path expression, overridden by any arguments specified in the optional kwargs argument to django.urls.path() or django.urls.re_path().
    • If no URL pattern matches, or if an exception is raised during any point in this process, Django invokes an appropriate error-handling view.
Iterators are used for traversing an object in Python which implements iterator protocol. It consists of two methods __iter__() and next().
In Django, a good use of iterator is when you are processing results that take up a large amount of available memory (lots of small objects or fewer large objects).
For more clarification please read when to use and when to not use iterator() in the Python Django ORM
https://stackoverflow.com/questions/12681653/when-to-use-or-not-use-iterator-in-the-django-orm
According to https://en.wikipedia.org/wiki/Django_(web_framework), Django was created in the fall of 2003, when the web programmers at the Lawrence Journal-World newspaper, Adrian Holovaty and Simon Willison, began using Python to build applications. It was released publicly under a BSD license in July 2005. The framework was named after guitarist Django Reinhardt.
Middleware is a function that acts on or transforms a request/response before/after it passes through the view layer (e.g. adding the user object to the request)
Some usage of middlewares in Django is:
  • It can be used for Session management,
  • User authentication can be done with the help of this.
  • It helps in Cross-site request forgery protection
  • Content Gzipping, etc.
Signal are inbuilt utility in Django. They allow to execute some piece of code based on some action or event is occurred in framework something like a new user register, on delete of a record.
Below is the list of some inbuilt signal in Django.
  • pre_save and post_save.
  • pre_delete and post_delete
  • pre_request and post_request
  • pre_request and post_request

Django closely follows the MVC (Model View Controller) design pattern, however, it does use its own logic in the implementation. Because the “C” is handled by the framework itself and most of the excitement in Django happens in models, templates, and views, Django is often referred to as an MTV framework. In the MTV development pattern:

  • M stands for “Model,” the data access layer. This layer contains anything and everything about the data: how to access it, how to validate it, which behaviors it has, and the relationships between the data.
  • T stands for “Template,” the presentation layer. This layer contains presentation-related decisions: how something should be displayed on a Web page or other type of document.
  • V stands for “View,” the business logic layer. This layer contains the logic that accesses the model and defers to the appropriate template(s). You can think of it as the bridge between models and templates.

Further reading https://djangobook.com/model-view-controller-design-pattern/

Follow the below steps to Install the development version of Django Framework.

    • Check out Django’s main development branch
$ git clone https://github.com/django/django.git
    • Make sure that the Python interpreter can load Django’s code. The most convenient way to do this is to use virtualenv, virtualenvwrapper, and pip.
    • After setting up and activating the virtualenv, run the following command:
$ pip install -e django/

Source:https://docs.djangoproject.com/en/2.0/topics/install/

Basically, we require three main things to set up static files in Django:

1) Set STATIC_ROOT in settings.py

2) Run manage.py collect static

3) Set up a Static Files entry on the PythonAnywhere web tab

Template can create formats like XML,HTML and CSV(which are text-based formats). In general terms template is a simple text file. It is made up of variables that will later be replaced by values after the template is evaluated and has tags which will control template’s logic.

Following points are specified by the Django Field Class type: –

  • It specifies the database column type.
  • It also specifies the default HTML widget which is availed while we render the form field.
  • The requirements of the minimal validation which is used in Django admin is also specified by the field class.
Yes, Django is free open source web framework for Python
You have to set the SESSION_ENGINE settings to “django.contrib.sessions.backends.file” to use file-based session.