Django | Difference between a project and an app

The project covers the entire application, while an app is a module or application within the project that deals with one dedicated requirement.

So, a project consists of several apps, while an app feature is in multiple projects.

Django | Model 

A model is a Python class in Django that is derived from the django.db.models.Model class. A model is used in Django to represent a table in a database. It is used to interact with and get results from the database tables of our application.
 

Django |  Loosely Coupled Framework

Django is called a loosely coupled framework because of its MVT architecture, which is a variant of the MVC architecture. It helps in separating the server code from the client-related code.

Django’s models and views take care of the code that needs to be run on the server like getting records from the database, etc., and the templates are mostly HTML and CSS that just need data from models passed by the views to render them.

Since these components are independent of each other, Django is called a loosely coupled framework.

Django | ORM

ORM stands for Object-relational Mapper. Instead of interacting with the database by writing raw SQL queries and converting the data returned from the query into a Python object, ORM allows us to interact with the database using objects of our model class. So, we just interact with our models and ORM converts these changes into SQL queries based on the database we are using, e.g., SQLite.
 

Django | Disadvantages 

Django has the following disadvantages:

• Django's modules are bulky.
• It is completely based on Django ORM.
• Components are deployed together.
• We must know the full system to work with it.

Django | Session Framework

Using the session framework, you can easily store and retrieve arbitrary data based on the pre-site-visitors. It stores data on the server side and takes care of the process of sending and receiving cookies. These cookies just consist of a session ID, not the actual data itself unless you explicitly use a cookie-based backend.

Django | Cookie 

A cookie is a small piece of information that is stored in the client's browser. It is used to store a user’s data in a file permanently (or for a specified time). Cookie has its expiry date and time and gets removed automatically when it gets expired. Django provides in-built methods to set and fetch cookies.

Here the methods to set and get cookie values are

• Set_cookie: this method is used to set the values of the cookie
• Get_cookie: this method is used to get the values of the cookie

Django | Middleware 

Middleware is something that executes between the request and response. In simple words, you can say it acts as a bridge between the request and response. Similarly In Django when a request is made it moves through middleware to views and data is passed through middleware as a response.

Django | NoSQL

NoSQL basically stands for “not only SQL”. This is considered an alternative to the traditional RDBMS or 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.

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.

Using the query method we can print SQL query from the queryset

post = Post.objects.all()

print(post.query)

Django | Check Version 

To check for the version of Django installed on your system, you can open the command prompt and enter the following command:

python -m django –version

You can also try to import Django and use the get_version() method as follows:

import django

print(django.get_version())

Django | Meta Class

A Meta class is simply an inner class that provides metadata about the outer class in Django. It defines such things as available permissions, associated database table name, singular and plural versions of the name, etc.

Django | Request/Response Cycle

Whenever a request is received by the Django server. The Request is processed by various middlewares and is passed to the URL Router. Then, the server looks for a matching URL in the urlpatterns defined for the project. If no matching URL is found, then a response with 404 Page Not Found status code is returned. If a URL matches,  then the corresponding code in the view file associated with the URL is executed to build and send a response.
. 
The response is given in the form of HttpResponse. The response is not limited to that. The Response can be PDF, JSON, or CSV. It provides built-in support to provide responses of various types.

Django | Features 

Features available in Django are

• Optimized for SEO
• Extremely fast
• A loaded framework that features authentications, content administrations and RSS feeds
• Exceptionally scalable to meet the heaviest traffic demand
• Highly secure
• Versatility, enabling you to create many different types of websites
• Admin Interface
• Object-relational mapping (ORM)
• Testing Framework
• Fantastic Documentation

Some of the more well-known companies that make use of Django are:’

• Instagram
• Mozilla Firefox
• Reddit
• YouTube
• Disqus
• Bitbucket
• Spotify
• NASA
• Pinterest
• Eventbrite, etc.

List the inheritance styles in Django

There are three possible inheritance styles in Django, and they are:

• Abstract Base Classes: This is used when we want to make the parent class hold the information which we don’t want to repeat again in the child class. Abstract Base Classes does not create any database table. It just makes changes in the database table created by the derived class.   
• Multi-table Inheritance: This is used when we want to subclass an existing model and there must be a database table designed for each model on its own. It means Multi-table Inheritance creates a database table for each derived class and base class
• Proxy models: This is used to modify the Python level behavior of the model, without modifying the model’s fields. It does not make any changes to the database.

Django | Set up Database

We need to edit the setting.py file present in the project, which contains all the settings related to the project.

By default Django comes with an SQLite database; The  SQLite database is available in the project after running the migrations commands:

python manage.py makemigrations
python manage.py migrate

SQLite database is available as a file on your system. Moreover, the name should be as a fully absolute or exact path along with the file name of the particular file.

The setting for SQLite database is already configured in the Django project, here is the sample code:

DATABASES = {
     'default': {
          'ENGINE' : 'django.db.backends.sqlite3',
          'NAME' : os.path.join(BASE_DIR, 'db.sqlite3'),
     }
}

if your database choice is different then you need to follow certain keys in the DATABASE like default items to match database connection settings.

• Engines: These are some engines for different databases:
  • ‘django.db.backends.postgresql_psycopg2’,
  • ‘django.db.backends.sqlite3’,
  • ‘django.db.backends.oracle’,
  • ‘django.db.backends.mysql’, and so on.
• Name: This represents the name of your own database. 
• if we are not using SQLite database then additional settings such as password, user, and the host must be added.

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'HOST': 'DB_HOST',
        'NAME': 'DB_NAME',
        'USER': 'DB_USER',
        'PASSWORD': 'DB_PASS',
    }
}

Django follows a Model-View -Template (MVT) architecture which is a variant of the MVC architecture. 

• Model: Logical data structure behind the entire app and signified by a database. A model is used in Django to represent a table in a database
• View: It's a user interface. What you see when you visit a website is called a user interface.
• Template: Deals with the presentation of data. Represented by HTML/CSS/Javascript files.

Compared to other frameworks, Django offers more code reusability. As Django is a combination of apps, copying those apps from one directory to another with some tweaks to the settings.py file won't need much time to write new applications from scratch.

That is why Django is the rapid development framework, and this kind of code reusability is not allowed in any other framework.

In Django, static files are the files that serve the purpose of additional purposes such as images, CSS, or JavaScript files. Static files managed by “django.contrib.staticfiles”. There are 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