Learning Django

Django is a Python-based free and open-source web framework, which follows the model-template-view (MTV) architectural pattern. Django's primary goal is to ease the creation of complex, database-driven websites. The framework emphasizes reusability and "pluggability" of components, less code, low coupling, rapid development, and the principle of don't repeat yourself. Python is used throughout, even for settings files and data models.

A guide to set up Django in a virtual environment

Create a folder: django-learn
cd django-learn
(Skip if already installed) Install Python's virtual environment: sudo apt install virtualenv and also sudo apt install python3-dev
Create a virtual environment in Python: virtualenv -p python3 env

Virtual environment env created for the directory django-learn
Activate env: source env/bin/activate

(env) must appear just prior to the bash prompt
Install Django for your virtual environment: pip3 install django
Create Django project folders: django-admin startproject demoproj

A single project can have multiple apps
cd demoproj

Inside the demoproj directory
Create a Django web app: python3 manage.py startapp demoapp
cd demoapp
Start the app: python manage.py runserver

Go to the localhost:8000. If you get to see the page with a green rocket then the Django app is running successfully

Day 1

Create a view in demoapp/views.py
We need to add path in demoproj/urls.py for each view we create
Create static and templates within demoapp directory
Put html files inside the templates folder
static folder has images and css folders that contains images and css files respectively
Open demoproj/settings.py and add your app name 'demoapp' to the INSTALLED_APPS list and also add this line [os.path.join(BASE_DIR, 'templates')] to TEMPLATES DIRS

Day 2

Style test3.html using an external CSS static/css/style.css
Style home.html using an external CSS static/css/home.css
Put javascript files inside static/js
Create a model in demoapp/models.py
- A model is the single, definitive source of information about your data. It contains the essential fields and behaviors of the data you’re storing.
- Generally, each model maps to a single database table.
- Each attribute of the model represents a database field.
- With all of this, Django gives you an automatically-generated database-access API.
- Django’s models provide an Object-relational Mapping (ORM) to the underlying database. ORM is a powerful programming technique that makes working with data and relational databases much easier.
- Refer docs.djangoproject.com
- Refer djangobook.com
Migrations are Django’s way of propagating changes you make to your models (adding a field, deleting a model, etc.) into your database schema.
- Create new migrations based on the changes you have made to your models: python manage.py makemigrations
- Apply and unapply migrations: python manage.py migrate
- Refer docs.djangoproject.com
Go to localhost:8000/admin for Django admin
To create a user: python manage.py createsuperuser
Register your newly created model with the admin
- Refer to Registering models with admin

Day 3

To view the Student model in the form of a table in a browser, we create a html table in a file: showstudents.html
To create a new entry for a student, we create a html form in createstudent.html
- To work with forms we need to create a python file: demoapp/form.py
- Refer Working with forms
- {% csrf_token %} provides cross site request forgery protection. Read this to know more
- Each data entry in our model has a unique id which is an auto-incremented value. We need to use it whenever we have to uniquely identify each row data.
To delete an entry, we simply write a function in views.py to do that.
To edit an entry, we create a form: editstudent.html, fetch the existing data (GET), modify it and submit the changes (POST).
- GET: Parameters remain in browser history because they are part of the URL
- POST: Parameters are not saved in browser history.
- Read this to learn more about their difference.

Day 4

Generating a csv file:
- getcsv method static generates a csv file
- getcsv_db method generates a csv file dynamically. It fetches data from the Student model.
- Refer Outputting CSV with Django
Generating a pdf file:
- pip3 install reportlab, we need it to output pdf.
- getpdf method static generates a pdf file.
- getpdf_db method generates a pdf file dynamically. It fetches data from the Student model.
- getpdf_nice method generates a pdf file with a well-formatted table that contains data from the Student model.
- Refer Outputting PDFs with Django

Day 5

Creating HTML templates:
- base.html includes header.html and footer.html
- index.html and about.html extends the template base.html
Added two methods in views.py to work with session:
- setsession sets session
- getsession fetches session
Added two methods in views.py to work with cookies:
- setcookie and getcookie
Read this to know that difference between session and cookie

To send email via Django, we need this library

    from django.core.mail import send_mail

and also add these few lines in settings.py

    EMAIL_USE_TLS = True
    EMAIL_HOST = 'smtp.mail.yahoo.com'
    EMAIL_PORT = 465
    EMAIL_HOST_USER = 'edummy17@yahoo.com'
    EMAIL_HOST_PASSWORD = 'Kolkata@0101'

Day 6

Authentication in Django
- Creating User account registration page, detailed instructions here

My setup:

Ubuntu 18.04.3 LTS
Python 3.6.8
pip 19.2.2
virtualenv 16.7.0

thecoducer/django-learn