Adding rails intro and modifired project 3

project3.md

@@ -37,27 +37,51 @@ one post can have many comments. Each comment belongs to the user and the post.
 
 ## List of supported endpoints
 
-- Navigating to the `/users` endpoint will list all `users` in your app
-
-- Navigating to the `/users/:id` will show the page with the information
-  about the `user` with the given `id`
+- Navigating to `/login` will provide you with a simple form where you can enter
+  your username.  No password is required.  When you submit the login form a new
+  user should be created if no user matches the username or an exiting user should
+  be logged in if the username exists.  Either way, you should be re-directed to
+  the root of the application `/`.  This should initialized a user session and
+  store the identity of the user in the session.
+
+- Navigating to `/logout` should remove the user information from the session
+
+- Navigating to any page other than `/login` without a user session should result
+  in a re-direct to `/login`
+
+- Navigating to the root of the application `/` when you are logged in will show
+  a list of all the posts from all users in chrolological order with the most
+  recently created post at the top.  Each post should include:
+  - The content of the post
+  - The username of the user who created the post
+  - The number of comments on a post (linkable to `/posts/:id` described below)
+  - The time the post was last updated
+  If the user is not logged in, they should be re-directed to the `/login`
+  - (Not Required) - Consider adding a search filter form input that allows you to
+    filter the list of posts to just those for the specified username
+
+- Navigating to the `/posts/:id` will show the page with the information
+  about the `post` with the given `id` including
+  - The content of the post
+  - The author of the post
+  - The list of comments for the post
+  - A form to add a new comment to a post.  Submitting this form should
+    show keep the browser on the same page but show the newly posted comment
 
   - Returns 404 if the id was not found.
 
-- From the browser, you can create the user
+- From the browser, you can create a post
 
-- From the browser, you can update the user
+- From the browser, you can update a post but only if you are the author
 
-- From the browser, you can delete the user
+- From the browser, you can delete a post but only if you are the author
 
-- There is a validation error for incorrect create or update action
+- From the browser, you can comment on any post
 
-  - E.g. Each user has to have an email and an error is displayed if this
-  required value is not provided
+- There should be a validation error for posts or comments that are attempting to influence the election.
+  Have fun with this.  A simple example might be a validation error for posts that include
+  the words "Trump" or "Harris"
 
-- Users index page (`/users`) shows the list of all the users; for each user
-  it shows the list of all posts that belong to the given user and for each
-  post it shows all the comments that belong to the post.
 
 ## Resources
 

schedule.md

@@ -93,7 +93,7 @@ The following schedule is subject to change, and many slide links are not yet ac
 ### Topics
 
 <!-- - #### Monday: Frontend React Deep Dive by David Acevedo -->
-- Client-side Caching & Content Delivery Networks
+- Rails Intro [slides](/slides/2024f/rails_introduction/index.html)
 - Server-Side Caching
 
 ### Tasks
@@ -108,6 +108,7 @@ The following schedule is subject to change, and many slide links are not yet ac
 
 ### Topics
 
+- Guest Lecture on React (Tu 10/29)
 - Relational Databases
 - Relational Databases and Rails
 - RDBMS Scaling

slides/2024f/rails_introduction/index.html

@@ -0,0 +1,307 @@
+---
+layout: presentation
+title: Introduction to Ruby on Rails
+---
+
+class: center, middle
+
+# {{page.title}}
+
+## CS291A: Scalable Internet Services
+
+---
+
+## History of Ruby on Rails
+
+- Created in 2004 by David Heinemeier Hansson (DHH)
+- Extracted from Basecamp project management tool
+- Released as open-source
+- Major release dates:
+  - 2004: Initial release (0.5)
+  - 2005: Rails 1.0
+  - 2007: Rails 2.0
+  - 2010: Rails 3.0
+  - 2013: Rails 4.0
+  - 2016: Rails 5.0
+  - 2020: Rails 6.0
+  - 2021: Rails 7.0
+
+???
+
+**Speaker Notes:**
+- Emphasize the origin of Rails from practical needs at Basecamp.
+- Highlight how it became popular quickly due to its simplicity and productivity for web applications.
+- Rails versions usually introduce major enhancements, focus on 6 and 7 being recent with performance improvements and modern JavaScript support.
+
+---
+
+## Key Benefits of Ruby on Rails
+
+- **Convention over Configuration (CoC)**
+- **Don’t Repeat Yourself (DRY)**
+- **Built-in Scalability**
+- **Full-stack solution**: Includes everything from front-end to database interaction
+- **Active community**: Constant improvements and large ecosystem
+- **RESTful Architecture**: Favors design of modern web apps
+
+???
+
+**Speaker Notes:**
+- CoC minimizes configuration; most things work "out of the box."
+- DRY ensures you write less code by abstracting common patterns.
+- Rails handles web, database, and background jobs, providing an all-in-one framework.
+
+---
+
+## Ruby on Rails vs. Other Frameworks
+
+| Feature                | Ruby on Rails         | Django              | Express.js       |
+|------------------------|-----------------------|---------------------|------------------|
+| Language               | Ruby                  | Python              | JavaScript (Node)|
+| Philosophy             | CoC, DRY              | Explicit is better  | Minimalist       |
+| Full-stack             | Yes                   | Yes                 | No               |
+| ORM                    | ActiveRecord          | Django ORM          | None (MongoDB popular)|
+| Performance            | High (Recent versions)| High                | High             |
+| Ecosystem              | Large                 | Large               | Moderate         |
+
+???
+
+**Speaker Notes:**
+- Discuss how Rails compares to Django in terms of philosophy—Rails focuses more on conventions, Django on explicit configuration.
+- Express.js is more lightweight, used primarily in Node.js ecosystems where developers want more control over the stack.
+
+---
+
+## Convention over Configuration
+
+- Rails uses **default conventions** to simplify configuration
+  - Default folder structures: `app/models`, `app/views`, `app/controllers`
+  - Convention-based file names, e.g., `UserController` automatically maps to `users` table
+  - Migrations manage database schema changes
+- Opinionated framework: makes assumptions to reduce decision fatigue
+
+???
+
+**Speaker Notes:**
+- Explain that CoC leads to faster development, reducing the number of choices developers need to make.
+- Emphasize that while opinionated, Rails allows flexibility through customization if necessary.
+
+---
+
+## Core Concepts of a Rails Application
+
+### 1. Model-View-Controller (MVC)
+
+- **Model**: Business logic and database interaction (ActiveRecord ORM)
+- **View**: User-facing templates (ERB, Haml, etc.)
+- **Controller**: Manages request-response lifecycle
+
+---
+
+### 2. Models
+
+- Represent database tables as Ruby classes
+- Utilize **ActiveRecord** ORM to abstract SQL interactions
+  - Example: `User.find(1)` instead of `SELECT * FROM users WHERE id = 1`
+
+---
+
+### 3. Views
+
+- Present data to users through templates
+- Can include logic (not recommended) and helpers for DRY
+
+---
+
+### 4. Controllers
+
+- Handle incoming requests and responses
+- Route logic to appropriate actions
+- E.g., `def show` method for displaying user data
+
+---
+
+### 5. Migrations
+
+- Version control for database schema
+- Create, update, or drop tables with simple Ruby commands
+  - Example: `rails generate migration AddEmailToUsers email:string`
+
+???
+
+**Speaker Notes:**
+- Break down the MVC architecture and emphasize how each piece interacts.
+- Mention that the model uses ActiveRecord, and migrations manage schema changes.
+- Give examples of each concept and how it ties into building a real-world application.
+
+---
+
+## Rails Application Structure
+
+- **app/**: Core components (models, views, controllers)
+- **db/**: Database files and migrations
+- **config/**: Application configurations, routes
+- **lib/**: Custom libraries and reusable code
+- **public/**: Static files (images, JS, CSS)
+
+???
+
+**Speaker Notes:**
+- Walk through the folder structure of a typical Rails application.
+- Focus on how conventions organize files and directories to make them predictable and easy to navigate.
+
+---
+
+## Rails Command Line Interface (CLI)
+
+- **`rails new app_name`**: Create a new Rails application
+- **`rails generate scaffold ModelName`**: Generate MVC components
+- **`rails db:migrate`**: Run pending migrations
+- **`rails server`**: Start the development server
+- **`rails console`**: Interactive Ruby console for testing
+- **`rails routes`**: Display application routes
+- **`rails dbconsole`**: Access the database console
+- **`rails test`**: Run test suite
+
+---
+
+## Rails Validations
+
+- Ensure data integrity and consistency
+- Built-in helpers for common validations
+  - Presence, uniqueness, format, length, etc.
+
+```ruby
+class User < ApplicationRecord
+  validates :email, presence: true, uniqueness: true
+end
+```
+
+???
+
+**Speaker Notes:**
+- Explain how validations ensure data quality and prevent invalid data from entering the database.
+
+---
+
+## Rails Associations
+
+- Define relationships between models
+- Common associations:
+  - `has_many`, `belongs_to`, `has_one`, `has_and_belongs_to_many`
+
+```ruby
+class User < ApplicationRecord
+  has_many :posts
+end
+
+class Post < ApplicationRecord
+  belongs_to :user
+end
+```
+
+???
+
+**Speaker Notes:**
+- Discuss how associations simplify querying and managing relationships between models.
+
+---
+
+## Rails Routing
+
+- Maps URLs to controller actions
+- RESTful routes: `GET`, `POST`, `PUT`, `DELETE`
+- Define routes in `config/routes.rb`
+
+```ruby
+Rails.application.routes.draw do
+  resources :users
+end
+```
+
+
+???
+
+**Speaker Notes:**
+- Explain how routing connects URLs to controller actions and RESTful conventions simplify API design.
+
+---
+
+## Rails Testing
+
+- **Minitest**: Default testing framework
+- **RSpec**: Popular alternative for BDD
+- **Fixtures**: Sample data for testing
+- **Factories**: Generate test data dynamically
+- **System tests**: End-to-end testing with Capybara
+
+---
+
+## Rails Controller Test Example
+
+Test that the `users#index` action returns the users list:
+```ruby
+class UsersControllerTest < ActionDispatch::IntegrationTest
+  test "should get index" do
+    get users_url
+    assert_response :success
+    assert_select "h1", "Users"
+    assert_select "li", User.count
+    assert_select "li", User.first.name
+  end
+end
+```
+
+or if it is a API endoint:
+```ruby
+class UsersControllerTest < ActionDispatch::IntegrationTest
+  test "should get index" do
+    get users_url, as: :json
+    assert_response :success
+    assert_equal User.count, JSON.parse(response.body).size
+    assert_equal User.first.name, JSON.parse(response.body).first["name"]
+  end
+end
+```
+---
+
+## Cookies and Sessions
+
+- **Cookies**: Store small pieces of data on the client side
+- **Sessions**: Store user data on the server side
+- Rails provides helpers for managing cookies and sessions
+
+```ruby
+# Set a cookie
+cookies[:user_id] = current_user.id
+
+# Access session data
+session[:user_id]
+```
+
+---
+
+## Before Action Callbacks
+
+- Run code before controller actions
+- Common uses:
+  - Authenticate users
+  - Set instance variables
+  - Redirect if conditions are not met
+
+```ruby
+class PostsController < ApplicationController
+  before_action :authenticate_user!
+
+    def index
+      @posts = Post.all
+    end
+
+  private
+
+  def authenticate_user!
+    @curent_user = User.find(session[:user_id])
+    redirect_to login_path unless @current_user
+  end
+end
+```