Rails Decal Fall 2017 Lab 2: Associations
Overview
Welcome to Lab 02 of the Rails Decal! In this lab, you will get practice with:
- Associations
- Migrations
- Routes
- MVC
Getting Started
Feel free to clone this app and get started from there. Remember to run bundle install. Alternatively, you may also start the app from scratch by doing:
rails new lab2
cd lab2
Models
Step 1 Let's begin by creating two models with the following attributes:
Trainer
name: a string containing the name of the trainer
age: an integer that contains the age of the trainer
Pokemon
name: a string containing the name of the pokemon
attack: an integer representing the attack points of the pokemon
Finally, run rails db:migrate to create your tables.
Step 2
Oh wait! I forgot that pokemon should also have a health column :( Luckily, we have migrations that can help us.
Generate a migration that adds a integer column to the pokemons table that represents the health points of a pokemon.
Hint: Is there a single command you can run in your terminal to generate this for you?
Associations
Let's create the association between pokemon(s) and trainers!
Create the migration that will add the foreign key, trainer_id column to the pokemons table.
Run rails db:migrate and play around in the rails console to create some trainers and their pokemon!
Model-View-Controller
Step 1
Create a trainers controller that contains an index method that will allow you to fetch all trainers from your database.
Hint: This method should contain one line.
Step 2
Create a route to '/' (localhost:3000) for this index method.
The view is provided for you in app/views/trainers/index.html.erb if you cloned this repo. Do however take a look the code in the view file to see how things are getting displayed.
Step 3
You should now be able to run rails server and immediately see a list view of all trainers and their pokemon! Congrats!
Seed File
Often times, it isn't very efficient to run rails console in order to create data models when you don't have a form to create them in your web app.
Another way we can quickly populate our database with default values is through a seed file, located in db/seeds.rb. Take a look at the file to see what it does.
Finally, to seed your database, run rails db:seed and refresh the page to see the new data.