In this article, we are going to provide a hands-on guide to implement authentication in Django based web application using Django’s inbuilt authentication system. If you are reading this article it means you are familiar with Django web framework and know the basic development with Django, so we will directly dive into building a web application to demonstrate the use of Django inbuilt authentication app/module. As we are aware that Django functionalities are implemented using the app and so authentication is also available as an app in the default installation of Django (we will discuss this later in details.).

So, what web application we are going to build? For demo purpose, our use case is like this,

“Suppose you are a web developer and want to create a web application which greets registered user with a welcome message once they provide correct username & password. After login user can logout from the system. Without login, any visitor will only get instruction that s/he is not login.”

Note: Again, for demo purpose, the application will not have a user registration system instead we will Django inbuilt function to create users for the application.

Now, we are clear with the idea of web application we are going to build, let get started. So, the major steps can be listed as below:

1. Create a new project (Web application)
2. Add a new app to project (a module)
3. Add authentication to your application

1. Create a new web application

To develop the login-based web application, we must create a project folder first which will all the codes and other related files. In this demo application, I am using conda virtual environment from Anaconda. So, let get started, Open the terminal and run below commands.

a.) Project folder

1. create a project folder

$mkdir DjangoLogin

2. Move to project folder

$cd DjangoLogin

b.) Create a virtual environment using Conda

$conda create -n LoginProject python=3.6

//conda is a command, available if you have installed Anaconda distribution of Python.

c.) Activate the virtual environment and work within it.

$source activate LoginProject

d.) Django Installation

(LoginProject)$ pip install django

// Notice the terminal prompt will have virtual environment name as a prefix

Once you have successfully, install Django in your virtual environment you will get the message as below:

#Successfully installed django-2.2.3 pytz-2019.1 sqlparse-0.3.0

e.) Create a django project

(LoginProject)$ django-admin startproject myloginproject

f.) Run the server and test the installation

(LoginProject)$ cd myloginproject

(LoginProject)$ python manage.py runserver

// This will result in running the server and if you visit the http://127.0.0.1:8000/ in your browser you will see the default django page as below.

2. Create a home page of the project

Once you got running the Django, it is time to change the home page to our own home page. For this purpose, here we are going to create an app (the app is Django way to organize web application,  there can be many apps in a Django project) myhome. This app will have all the required files for our web application.

a.) Create app within Django project

(LoginProject)/myloginproject$ python manage.py startapp myhome

After creating the app, we have to add this to installed_apps sections of settings.py.

In this web application, I am going to use a template to show the contents to the user. Django offers two ways to use the template with the project, first via app-specific templates folder which holds all the templates files and second project-specific global templates folder. In this project, I am going to use the project specific templates scheme. So, for that, we have to create a templates folder within the project template.

b.) Creating templates

(LoginProject)/myloginproject$ mkdir templates

(LoginProject)$/myloginproject/templates$ touch home.html

Note: It is required to make changes in settings.py to enforce global /project-specific templates by adding the path in DIRS as below. Open the settings.py file and add below lines.

'DIRS': [os.path.join(BASE_DIR, 'templates')],

Once you have done with templates settings, let add something to home.html and create a view for the same.

c.) Create template (home.html)

Open home.html and add below code.

<p>
  Welcome to Coding Infinite Homepage.
</p>

d.) Create a view for the app (myhome/views.py)

from django.views.generic import TemplateView

class HomePageView(TemplateView):
    template_name = 'home.html'

Once our view and template are ready it is time to give route to them i.e. adding them to Django routing scheme via urls.py file. Again, the Django project can have project-specific route file or app-specific, it is good practice to have app-specific routes and then add them to the project route file, which keeps things clean and easy to follow. By default, the app doesn’t have the urls.py file so let create that as follow:

e.) Create urls.py and add the route

(LoginProject)$/myloginproject/myhome$ touch urls.py

Add below code to urls.py, which will add our template home to the root path.

from django.urls import path

from .views import HomePageView

urlpatterns = [
    path('', HomePageView.as_view(), name='home'),
]

f.) Add app routes to project route (myloginproject/urls.py)

add below line to the urls.py

path('', include('myhome.urls')),

"""myloginproject2 URL Configuration

The `urlpatterns` list routes URLs to views. For more information please see:
    https://docs.djangoproject.com/en/2.2/topics/http/urls/
Examples:
Function views
    1. Add an import:  from my_app import views
    2. Add a URL to urlpatterns:  path('', views.home, name='home')
Class-based views
    1. Add an import:  from other_app.views import Home
    2. Add a URL to urlpatterns:  path('', Home.as_view(), name='home')
Including another URLconf
    1. Import the include() function: from django.urls import include, path
    2. Add a URL to urlpatterns:  path('blog/', include('blog.urls'))
"""
from django.contrib import admin
from django.urls import path,include


urlpatterns = [
    path('admin/', admin.site.urls),    
    path('', include('myhome.urls')),
]

With this, we are good to go and we have added an app to our project successfully. Run the server and visit the  http://127.0.0.1:8000/ in your browser you will see the content of your home.html template file.

3. Add Authentication to the app

Once you have successfully running app, it is time to add authentication to your app. You would have observed that anyone than visit the URL and can view the content but we want the only visitor with login credentials can see the contents after properly login to the system. So, let build login and logout to our existing app.

Building login and logout is a complex process and there are chances of mistakes, so Django comes with authentication app (as explained earlier, Django project are organized through app and app can be used to extend the functionalities.). So, there is an authentication app by default to every Django project (django.contrib.auth).

So, this auth app have almost everything we need to implement authentication to our application, we just have to attach authentication to our existing app by following below steps:

a.) Creating login page

We have to create a login template to have the login form. Django follows some default naming convention like, it will look for a login.html in registration folder with templates folder. So, let create the folder and template file.

(LoginProject)$/myloginproject/templates$ mkdir registration

(LoginProject)$/myloginproject/templates$ cd registration

(LoginProject)$/myloginproject/templates/registration$ touch login.html

b.) Template extension

Django offers ways to reuse an already existing template to extend the new template file. So, for our demo application, we will have a base.html which will be extended by all other templates.

(LoginProject)$/myloginproject/templates$ touch base.html

c.) Add content to templates/base.html, templates/home.html and registration/login.html

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>{% block title %}Coding Infinite: Tutorial for Web Login using Django{% endblock %}</title>
</head>
<body>
  <main>
    {% block content %}
    {% endblock %}
  </main>
</body>
</html>

{% extends 'base.html' %}

{% block title %}Login{% endblock %}

{% block content %}
<div style="text-align:center"><h2>Login</h2></div>


<div style="text-align:center">

  <form method="post" id="form_login">
    {% csrf_token %}
    {{ form.as_p }}
    <button type="submit">Login</button>
  </form></div>
{% endblock %}

{% extends 'base.html' %}

{% block title %}Home{% endblock %}

{% block content %}
{% if user.is_authenticated %}
  <div style="text-align:center">Hi {{ user.username }}! Welocme to Coding Infinite!!</div>
  <p><a href="proxy.php?url={% url 'logout' %}">logout</a></p>
{% else %}
  <p>You are not logged in</p>
  <a href="proxy.php?url={% url 'login' %}">login</a>
{% endif %}
{% endblock %}

The code in both files are self-explained, much of them are HTML and basic Django. In the login.html, following lines are important.

    {% csrf_token %} —- This is for security and prevent cross-site forgery attack.

    {{ form.as_p }}    —-  This is the default form class from django and auth app render as per login requirements.

We have changed a lot in home.html, to add login and a logout link. The login link will call login template and logout will end the session.

d.) Add auth app to project route (urls.py)

Auth app is default in Django but the path is not included in the route so we have to add auth path to project’s urls.py.

path('accounts/', include('django.contrib.auth.urls')),

With this, we have added authentication to our system. Let’s run and check the output.

Clicking on login will bring you the login form but do you have created a user? No, giving any login credential will result in an error such as “no such table: auth_user”. So, what is this error, many app needs database table to work and Django has the table created by default but we need to activate those table and we can do that will migrate command with manange.py.

e.) Creating default database tables

(LoginProject)$/myloginproject$ python manange.py migrate

After successful migration, again run the server and test the application. This time you will not get the previous error but wrong credentials message  (“Please enter a correct username and password. Note that both fields may be case-sensitive.”) will be shown for any login credentials. Why so?

Because we have not created any user for our authentication system. This can be done via a registration link but for demo purpose, we will use the default user creation process comes with Django.

f.) Create user

(LoginProject)$/myloginproject$ python manage.py createsuperuser

This will prompt the user to give username, email, password and after successfully giving all details a user will be created and we can login with the same credentials. Now, can run the test server and test the page. This will again give an error, page not found (404) as below:

So, what is this error? This is an error because we have not specified the landing page after login which should be our home template. So, we have to specify landing page for login and logout.

g.) Adding landing page

Add below two lines at the bottom of settings.py of project.

LOGIN_REDIRECT_URL = 'home'

LOGOUT_REDIRECT_URL = 'home'

Now, with this is our web login demo is ready and will work smoothly. Go and test your application.

 Below is the video for showing the working of the demo application.

Note: For writing this article, I took help from this tutorial and thanks for the same.

Here’re some more Articles, you might be interested:

— Top 5 Python Web Frameworks to Learn

— Developing Chat Application in Python with Source Code

— Data Visualization in Python Using Simple Line Chart

The post Web Login Page Tutorial using Django Authentication System | Python appeared first on Coding Infinite.

The web application has two parts, client side and server side. The client side is mainly HTML, CSS and Javascript and considered a way to present information to the user. The server-side part of the application has all the business logic and often has a complex part of the application. Server-side web development is done in many languages like Java, .Net, PHP, Ruby on Rails, Javascript etc., Python is also capturing the share of server-side development with its various web frameworks.

Developing server side in the programming language without any framework is very tedious as the developer has to write code for every repeating thing, to recuse developer and fasten the web development most of the programming has web framework. A web framework is a pre-written code for doing repeating tasks of web development and provide the abstract form for writing a web application. For example, user authentication is a pre-built feature of web framework and almost all web framework provide an abstract layer on using databases. So, web framework helps web developer to develop web application faster and more efficient with well-written modules and functionalities. Python is open source programming and many of its web frameworks are also opensource and free for example Flask, Django, web2py, bottle etc.

In this article, the top 5 Python web frameworks are discussed with sample example and other related information which will help the developer to choose the right framework for their work. Web frameworks can be grouped into two categories: Full-stack framework (many modules) and Micro-framework (thin with limited features).

1. Django

Django is a full stack web framework suitable for a large and complex project. It helps in rapid and clean development of a web project. Django is free and opensource and built & maintain by a ton of experienced web developers. According to Django documentation, some of the listed features of Django are, ridiculously fast, reassuringly secure, exceedingly scalable, and incredibly versatile.

2. Web2py

Web2py is another full-stack framework for rapid development of fast, scalable, secure and portable database-driven web-based applications.

3. Flask

Flask is a micro-framework which has Werkzeug, Jinja 2 as the core engine. It is BSD license. It is very light and suitable for a small project. Flask is also very useful for API (Application Programming Interface) development.

Here’s the sample Code:

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

4. Bottle

The Bottle is a fast, simple and lightweight micro web-framework. It is distributed as a single file module and has no dependencies other than the Python Standard Library. It is good for fast prototyping and personal website.

Here’s the sample Code for Bottle:

from bottle import route, run, template

@route('/hello/<name>')
def index(name):
    return template('<b>Hello {{name}}</b>!', name=name)

run(host='localhost', port=8080)

5. CherryPy

CherryPy is a minimalist Python Web Framework. It has features like reliability, easy to run multiple HTTP servers, flexible plugin system, built-in tools for caching, encoding, sessions, authentication, static content, swappable and customizable, built-in profiling, coverage, and testing support.

Here’s the Example Code:

import cherrypy

class HelloWorld(object):
    @cherrypy.expose
    def index(self):
        return "Hello World!"

cherrypy.quickstart(HelloWorld())

Characteristics Comparison

Here’s a little comparison between all 5 frameworks listed above.

How to choose?

We have listed only 5 Best web-framework of Python but there are so many out there. So, the genuine question would be “how to choose which framework to use?”. Giving a direct answer would be biased so apart from the above information, we have also decided some metrics regarding these frameworks which are based on GitHub, stack-overflow and naukri.com. Github and stack-overflow is developer playground so they offer few options like giving stars to project hosted on GitHub and asking question-related to CS and IT concepts on stack-overflow. On the other hands naurki.com list job opening related to technologies and required skills. We have taken four metrics out of these sites, all the metric are not very robust but could help to understand about these web-frameworks. (Note: All the value are collected from public search as on 19 June 2019.

a) Github Star: Total stars given to project by users.

b) Github releases: How many releases each project has, this reflect the active project and mature projects.

c) Stack-overflow questions: How many questions are asked for a particular topic.

d) Posted-jobs: How many job posting is there related to technologies or skills.

From the above data, one can easily understand that Django is popular in full-stack web-framework and Flask is popular in micro-framework. Other web-frameworks are also gaining popularity and can be the best choice for learning and contributing to the project or build Application on the top of these web-frameworks.

There are so many other web-frameworks based on Python like TurboGears, pyramid etc. In-depth how-to and working of these web-frameworks can be read from the website and we have also plan to publish a detailed article on these in future. Keep checking this space for the update.

Thank you for being here and keep reading…

Here’re some more Articles you might be interested:

— Here Are The Ten Best Programming Languages to learn

— Some Keeps to avoid bugs while Programming

— 10 Simple Rules For Best Programming Practices

The post Top 5 Python Web Frameworks to Learn in 2019 appeared first on Coding Infinite.