Many to Many Multi Select and Polymorphic Select in Rails 4

• The Many to Many Multi Select is in lion_tamers/_form.html.erb and can be viewed from localhost:3000/lion_tamers/new, but you need to seed your DB first - or create a few lions first, then create your lion tamer.

• The trick is to have :lion_ids => [] as a param in your lion_tamers_controller. Having :lion_ids as a param is a mistake and won't work, because the multi select is submitting the values as an array.

• The Polymorphic Select can be viewed from localhost:3000/cat_toys/new, but like above it'll be better if you make some lions and panthers first or seed your DB. The fun stuff is in the cat_toys_controller.rb file to make the polymorphic select work.

• however, if you want to be really fancy then leverage the global id gem for a polymorphic select, which will be built into rails 4.2 (we're using 4.1.9 now) http://stefan.haflidason.com/simpler-polymorphic-selects-in-rails-4-with-global-id/

ZooMS RAILS (Zoo Management System)

• This is an assignment
• Screencasts here:
  1. Going over models, schema, routes, lions, leading into lion_tamers http://screencast.com/t/Bk5Fqi60

Step 0 - SETUP

• rails new zooms --database=postgresql

• Go into the folder

• bundle install to install all the gems (pry-rails)

• rake db:create to create the server

• Your data model is this:

• a lions table and a lion.rb model:

  • columns: birthdate (date), name (string), about (text), weight (integer), health (integer), health_notes (text)

• a lion_tamers table and a lion_tamer.rb model:

  • name (string), experience (integer), living (boolean)

• a joining table for lions and lion_tamers

  • you can use this for rails to automatically make it for you :)
    • rails generate migration CreateJoinTableLionTamerLion lion_tamer lion

• run the migrations

bonus HARD

• what if one table can belong to many tables - how do we do this? You use a technique called polymorphism. Let's do this. I had the opportunity of being the first one to introduce this into MediaMath back in 2013.

• read about polymorphism here:

  • http://guides.rubyonrails.org/association_basics.html#polymorphic-associations

• make a panthers table and a panther.rb file

  • columns: name, claw_length (integer)

• make a cat_toys table and a cat_toy.rb file

• we'll make it so a panther can have a cat toy or a lion can have a cat toy. Sound simple, but it's not. We need to have a string column that stores the type of object (Lion or Panther) that owns that cat_toy in the cat_toys table and a foreign_id column that stores the id of that Panther/Lion that owns that cat_toy.

• run this cmd in your terminal to make a polymorphic association among the panthers, lions and cat_toys tables rails generate migration AddToyableToCatToys toyable:references{polymorphic}

• run the migrations

Step 1 - MODELS

• A lion_tamer has a many to many relationship with lions

bonus

• make a polymorphic relationship among lions, panthers and cat_toys so that

• In panther.rb

  • has_many :cat_toys, :as => :toyable, dependent: :destroy

• In lion.rb

  • has_many :cat_toys, :as => :toyable, dependent: :destroy

• In cat_toy.rb

  • belongs_to :toyable, :polymorphic => true

Validations

• add validations for every column of the lions and lion_tamers tables

bonus

• add validations for every column of the pantehrs and cat_toys tables

SEED

• throw stuff into your seed file and then run

• rake db:seed to populate our tables.

• OR

  • open up your rails console by doing: rails c
    • and do Lion.create({...})
      • the ... has the columns and values
    • and do LionTamer.create({...})
    • etc ...

• bonus: do the seeding for panthers and cat_toys

CHECK TO SEE IF ITS ALL GOOD

• check your schema.rb file if it's all good
• go into the rails console to see if everything's good like this: rails c

STEP 4 - ROUTES

• use restful routes for everything (resources :lions)

• bonus: do the routes for panthers and cat_toys

CHECK TO SEE IF ITS ALL GOOD

• rake routes

STEP 5 - CONTROLLERS

• make your controllers

• bonus: do the controllers for panthers and cat_toys

STEP 6 - VIEWS

Your views will be similar to David's solution for the museumr app

• make sure the show pages show all the column data

• make sure the index pages show all the records

• make sure the forms let you edit every column

• make sure you use partials for the forms

• on the lion_tamers form

  • let the user select the lions that the lion_tamer works with

<div class="field">
  <%= f.label :lion_ids %><br>
  <%= f.select :lion_ids, @lions.collect{|d| [ "#{d.name}", d.id ]}, { :selected => @lion_tamer.lions.pluck(:id) }, { :multiple => true, :class => 'select2'} %>
</div>

• make sure you have @lions = Lion.all in your new and edit actions of your lion_tamers_controller.rb

• make sure you can edit, delete and make a new record on all the index views

MINOR BONUS

• use select2 on the multi selects

• Put this in your gemfile, and run bundle install gem "select2-rails"

• in your application.css file replace it with this:

/*
 * This is a manifest file that'll be compiled into application.css, which will include all the files
 * listed below.
 *
 * Any CSS and SCSS file within this directory, lib/assets/stylesheets, vendor/assets/stylesheets,
 * or vendor/assets/stylesheets of plugins, if any, can be referenced here using a relative path.
 *
 * You're free to add application-wide styles to this file and they'll appear at the bottom of the
 * compiled file so the styles you add here take precedence over styles defined in any styles
 * defined in the other CSS/SCSS files in this directory. It is generally better to create a new
 * file per style scope.
 *
 *= require select2
 *= require_tree .
 *= require_self
 */

• in your application.js file replace it with this:

// This is a manifest file that'll be compiled into application.js, which will include all the files
// listed below.
//
// Any JavaScript/Coffee file within this directory, lib/assets/javascripts, vendor/assets/javascripts,
// or vendor/assets/javascripts of plugins, if any, can be referenced here using a relative path.
//
// It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
// compiled file.
//
// Read Sprockets README (https://github.com/sstephenson/sprockets#sprockets-directives) for details
// about supported directives.
//
//= require jquery
//= require jquery_ujs
//= require turbolinks
//= require select2
//= require_tree .

• make a new file in your javascripts folder called select_two.js and paste this in:

var ready;
ready = function() {
	$('.select2').select2();
};


$(document).ready(ready);
$(document).on('page:load', ready);

• now your multi selects will look sweeeeet as long as you have the select2 class on them.

Bonus - hard

• Make the form for cat_toys is made so that you can choose whether a lion or panther owns the particular cat_toy. You'll have to do some research and playing around to figure this out. There are many different ways to make this happen.

• show the cat toys that a lion owns on the show page

• show the cat toys that a panther owns on the show page

• show all the lions' cat toys on the lions index

• show all the panthers' cat toys on the panthers index

• on a cat_toy show page, show the lion or panther that owns it

• on the cat_toys index page, show the lion or panther that owns it for all the cat_toys.