Introduction to JS

• https://jsbin.com
  • Run HTMS, CSS, JS online

What is JavaScript?

• JavaScript is a dynamic, weakly typed programming language which is compiled at runtime.
• It can be executed as part of a webpage in a browser or directly on any machine (“host environment”).
• JavaScript was created to make webpages more dynamic (e.g. change content on a page directly from inside the browser).

Cookies

• Cookies are small strings(max size 4KB) of data that are stored directly in the browser.
• They are a part of the HTTP protocol, defined by the RFC 6265 specification
• Sent to server on ecah request
• Cookies are usually set by a web-server using the response Set-Cookie HTTP-header.
• One cookie must not exceed 4KB, 20+ cookies per site(depends on the browser)

Node Js

Node.js lets you run JavaScript outside the browser, primarily for building back-end services, tools, or full-stack applications.

Node Installation

Check version

node -v

npm -v

nvm -v

Option 1: Install from Official Website

• Go to: https://nodejs.org
• You’ll see two options:
  • LTS (Long-Term Support) – Stable, recommended for most users
  • Current – Latest features, but may be less stable.
• Download and install the LTS version.

This installs both Node.js and npm (Node Package Manager).

Javascript learning path

1. How The Web Works

• Type the URL and press Enter
• The URL gets resolved
• A Request is sent to the server of the website
• The response of the server is parsed
• The page is rendered and displayed

Throttling

API rate limiting is a technique used to control the number of requests a user or client can make to an API within a specific time frame. In Django, you can implement rate limiting using third-party libraries like Django REST Framework’s (DRF) throttling or by integrating specialized libraries like django-ratelimit.

4.1 Using Django REST Framework (DRF) Throttling

DRF provides built-in throttling classes to enforce rate limits.

Period should be one of: (’s’, ‘sec’, ’m’, ‘min’, ‘h’, ‘hour’, ’d’, ‘day’)

Logger

Print statement generally does not work in production so, to get message we use logger

• Troubleshooting made easier
• Runtime information in production
• https://www.youtube.com/watch?v=ziegOuE7M4A&list=PL2NFhrDSOxgXXUMIGOs8lNe2B-f4pXOX-&index=4

What is Logging?

How Logging Works in Django

• Django comes with Python's built-in logging module to leverage system logging.
  1. Loggers
  2. Handlers
  3. Filters
  4. Formatters

Loggers

• Loggers are basically the entry point of the logging system.
• If the log-level is same or exceeds the log-level of the logger, the message is sent to the handler for further processing.

DEBUG:		     10 --> Low-level system information
INFO:		     20 --> General system information
WARNING:	     30 --> Minor problems related information
ERROR/EXCEPTION: 40 --> Major problems related information
CRITICAL:	     50 --> Critical problems related information

dblogger.debug("Test Debug")

dblogger.info("Test Info")

dblogger.warning("Test Warning")
dblogger.warn("Test Warn")  # Depricated

dblogger.error("Test Error")
dblogger.exception("Test Exception")

dblogger.critical("Test Critical")

Handlers

Handlers basically determine what happens to each message in a logger eg: write to a file or console.

𝗖𝗿𝗼𝘀𝘀-𝗢𝗿𝗶𝗴𝗶𝗻 𝗥𝗲𝘀𝗼𝘂𝗿𝗰𝗲 𝗦𝗵𝗮𝗿𝗶𝗻𝗴 (𝗖𝗢𝗥𝗦)

CORS is a security mechanism enforced by web browsers to restrict cross-origin HTTP requests.

CORS is a mechanism implemented by browsers that block websites to request data from some other URL. When a browser makes a request, it adds an origin header to the request message. If it goes to the server of the exact origin, it is allowed by the browser; if it does not, the browser blocks it. gets error like Cross-Origin Request Blocked

Django postgres full text search

• Unlike relational databases, full-text search is not standardized.
• There are several open-source options like ElasticSearch, Solr, and Xapian.
• For general uses
  • We can stick with the full-text search capabilities that many relational (like Postgres, MySQL, SQLite)
  • And non-relational databases (like MongoDB and CouchDB) offer.

Basic Search

• In Django you’ll typically start by performing search queries with contains or icontains for exact matches.
• The Q object can be used as well to add AND (&) or OR (|) logical operators.
• Limitations
  • Only exact match is shown –> similar words excluded
  • Stop word(article) all has same weight
  • complex lookups not possible

from django.db.models import Q

ProductDetail.objects.filter(Q(name__icontains=query))

Quote.objects.filter(Q(name__icontains=query) | Q(quote__icontains=query))

• Eg:
  • query = pony
  • then ponies != pony

The search lookup(Single Field Search)

• To use the search lookup, django.contrib.postgres must be in your INSTALLED_APPS.
• Used for Single Field Search
• Advantage
  • It takes similar words into account
    • ponies, pony

INSTALLED_APPS += ['django.contrib.postgres']

ProductDetail.objects.filter(name__search=query)

SearchVector

• To search against multiple fields and on related models, you can use the SearchVector

Entry.objects.annotate(search=SearchVector('body_text') + SearchVector('blog__tagline')).filter(search=query)

Quote.objects.annotate(search=SearchVector("name", "quote")).filter(search=query)

SearchQuery

SearchQuery translates the terms the user provides into a search query object that the database compares to a search vector. By default, all the words the user provides are passed through the stemming algorithms, and then it looks for matches for all of the resulting terms.

# Topic covered
* Authentication
  * Authentication vs Authorization
  * How authentication is determined
  * Setting the authentication scheme
* Types of Authentication
  * TokenAuthentication
  * SessionAuthentication
  * BasicAuthentication
* Permissions

# Topic covered
* TokenAuthentication
* Django-rest-auth