associations-cr-cm.md

Banking Challenge Create a new rails application and database

$ rails new credit_card_challenge_app -d postgresql -T
$ cd credit_score_app
$ rails db:create

Setup

Create a model for owner

    $ rails g model Owner name:string address:string 
    $ rails db:migrate

add some owners in rails

    $ rails c
    $ Owner.create name:"Bob Marley", address:"420 blaze way"
    $ Owner.create name:"pinochio", address:"666 wooden nose rd"
    $ Owner.create name:"John Daily", address:"626 golf course cr"

Create a model for credit card

    A credit card has a number, an expiration date, and an owner
        $ rails g model Card number:integer exp:string owner_id:integer 
        $ rails db:migrate

An owner has a name and address, and can have multiple credit cards

    in app-model-owner : 
        class Owner < ApplicationRecord
        has_many :cards
        end
    in app-model-card : 
        class Card < ApplicationRecord
        belongs_to :owner
        end
        $ bobby = Owner.fist
        $ bobby.cards.create number:"666555", exp:"54/88"
        $ woody = Owner.find 2
        $ woody.cards.create number:"8675309", exp:"22/99"
        $ bobby.cards.create number:"222555", exp:"51/88"
        johnny = Owner.last
        $ johnny.cards.create number:"42042069", exp:"06/20"
        $ bobby.cards.create number:"2654", exp:"25/88"
        $ bobby.cards.create number:"2255555", exp:"51/98"
        $ bobby.cards <!-- used to check how many cards bobby has -->  

Challenges Create three owners and save them in the database in rails console. done

done Create a credit card in the database for each owner done Add two more credit cards to one of the owners Stretch Challenge Add a credit limit to each card $ rails generate migration add_limit_2_cards in migrate-new migrate area class AddLimit2Cards < ActiveRecord::Migration[7.0] def change add_column :cards, :limit, :integer end end Find the total credit extended to the owner with multiple credit cards rails c $ bobby = Owner.first rails c $ bobby.cards.sum(:limit) *to change one of bob marley card limits rails c $ bobby.cards.where(id:3).update limit:4000 *tested with rails c $ bobby.cards.sum(:limit) output: