Music Inventory

This inventory system application will let record labels track their Bands, Albums and Tracks. Additionally we'll offer user accounts so users can comment on our inventory.

Learning Goals

• Be able to build User Authorization
• Know how to nest routes
• Be able to link between different views using a tags and rails URL helpers
• Be able to trigger controller actions from views using forms and links
• Know how to check that a current user exists before displaying content
• This project will not use form_for

Warm Up: Authentication

User model will have prerequisites of authentication. Email addresses are in lieu of usernames; in the bonus phase, emails will be sending confirmation emails and other stuff.

users table: store an email, password_digest and session_token. Add database constraints (require all fields), and indices to ensure uniqueness of emails and speed up the lookup by session_token.

• Methods to deal with the session token: User::generate_session_token, User#reset_session_token! and User#ensure_session_token.

• User#password=(password) method which actually sets the password_digest attribute using BCrypt, and a User#is_password?(password) method to check the users' password when they log in

  • In #password=, I will use self.password_digest=. (self.___= calls a setter method defined for us by ActiveRecord, which is the state that is saved by self.save. While @___ makes a new instance variable, unrelated to self.save)

• In the User model, there will be an after_initialize callback to set the session_token before validation if it's not present.

• I need a User::find_by_credentials(email, password) method.

I will next need a UsersController and SessionsController.

• I need methods on UsersController to allow new users to sign up.

  • They will be immediately logged in after signing up!

• The SessionsController handles all Authorization actions, so I won't make a model for this.

  • As usual, I will make Controller actions and routes for logging in and out. The session will be a singular resource!
  • SessionsController#create will re-set appropriate user session_token and session[:session_token]
  • For testing, I will redirect them to a UsersController#show page until a proper view template is created.

Don't Repeat Yourself! I will write some methods in the abstract class ApplicationController. There will be appropriate methods for views as helper methods, syntactically as helper_method :current_user.

• #current_user returns the current user.
• #logged_in? returns boolean indicating if the user is signed in.
• #log_in_user!(user) resets the users session token and cookie.

User Routes

    session POST   /session(.:format)                     sessions#create
            DELETE /session(.:format)                     sessions#destroy
new_session GET    /session/new(.:format)                 sessions#new
      users POST   /users(.:format)                       users#create
   new_user GET    /users/new(.:format)                   users#new
       user GET    /users/:id(.:format)                   users#show

I will create login/signup views and edit application.html.erb layout so that a logged in user is displayed a "sign-out" button and a logged-out user is displayed links to sign-up or sign-in pages. After that, it will be time to add some styling!

Basic Styling

• I will need a header with the title of the Music Inventory Application with a cool font in my application.html.erb
• flex in CSS should display logged-in/logged-out status on the right side of my header.
• I should make my <a> elements look more like buttons, which usually involves changing background_color and border-radius.
• I need to have proper spacing and line alignment for my session forms.

Phase 1: Bands, Albums, and Tracks

We cannot fully implement user features without building out core features of our inventory system.

When following the Model View Controller Software Architecture, it is best to build out one set of features and resources at a time.

• Database Migrations (Schema)
• Model definition (Ruby class with validations, associations, and helper methods)
• Routes (URL Path)
• Controllers Actions (Business Logic)
• Views (User Interface should match up with Controller Actions rendering them)

Bands

• In the Migration CreateBands, I will create a bands table with a name (required) column with server timestamps.
• I will create a Band model with a validation to ensure name is not null (value actually exists).
• Representational State Transfer REST API:

bands     GET    /bands(.:format)                       bands#index
          POST   /bands(.:format)                       bands#create
new_band  GET    /bands/new(.:format)                   bands#new
edit_band GET    /bands/:id/edit(.:format)              bands#edit
band      GET    /bands/:id(.:format)                   bands#show
          PATCH  /bands/:id(.:format)                   bands#update
          PUT    /bands/:id(.:format)                   bands#update
          DELETE /bands/:id(.:format)                   bands#destroy

• I can create a reusable form template _form.html.erb for the different pages rendered by BandsController. Depending on the BandController action, a ternary operator checking band.persisted? will change the form's action and method override to the correct URL path and HTTP Request method.
• For each BandsController action, I will first write the action, test it, then create the html.erb view that will be rendered.
• config.action_controller.default_protect_from_forgery = false would disable the CSRF Protection in config/application.rb, which is meant to prevent phishing from fraudlent or fake copy sites. After testing the API endpoints manually one by one, we will need to re-enable CSRF protection before production!

Albums

I will follow the same design pattern as previously used with Bands, starting with the database migration.

Album Model:

• Not be called Record, because it will conflict with ActiveRecord's record_id.
• belongs_to a band, which will need a has_many association to band
• Contains a title and year
• States whether it is a live or studio album
  • Boolean with a default value
• Representational State Transfer REST API:

new_band_album GET    /bands/:band_id/albums/new(.:format)   albums#new
        albums POST   /albums(.:format)                      albums#create
    edit_album GET    /albums/:id/edit(.:format)             albums#edit
         album GET    /albums/:id(.:format)                  albums#show
               PATCH  /albums/:id(.:format)                  albums#update
               PUT    /albums/:id(.:format)                  albums#update
               DELETE /albums/:id(.:format)                  albums#destroy

Tracks

The same workflow for Bands and Albums will be used for Tracks.

Track Model:

• Belongs to an album, with corresponding model associations to Band and Album
• Has properties of string title, ord integer (track number), and optional text lyrics
• Boolean property of bonus, with false being a regular track
• Representational State Transfer REST API:

new_album_track GET    /albums/:album_id/tracks/new(.:format) tracks#new
         tracks POST   /tracks(.:format)                      tracks#create
     edit_track GET    /tracks/:id/edit(.:format)             tracks#edit
          track GET    /tracks/:id(.:format)                  tracks#show
                PATCH  /tracks/:id(.:format)                  tracks#update
                PUT    /tracks/:id(.:format)                  tracks#update
                DELETE /tracks/:id(.:format)                  tracks#destroy

License Information

    Music Inventory - Inventory System for Record Labels
    Copyright (C) 2020  Mark Calvelo

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.