irb does not have access to my models (NameError: uninitialized constant) - ruby

Question

I am receiving this error when trying to create a new 'Pin' in IRB. For example:
irb(main):001:0> #pin = Pin.first
NameError: uninitialized constant Pin
OR
irb(main):001:0> #pin = Pin.new
NameError: uninitialized constant Pin
I must of changed something as it was working before. Unfortunately, I cannot find the error
Here is my pins controller:
class PinsController < ApplicationController
before_action :authenticate_user!, except: [:index, :show]
before_action :correct_user, only: [:edit, :update, :destroy]
before_action :set_pin, only: [:show, :edit, :update, :destroy]
def index
#pins = Pin.all
end
def show
#pin = Pin.find params[:id]
end
def new
#pin = Pin.new
end
def edit
end
def create
#pin = Pin.new(pin_params)
if #pin.save
redirect_to #pin, notice: 'Pin was successfully created.'
else
render action: 'new'
end
end
def update
if #pin.update(pin_params)
redirect_to #pin, notice: 'Pin was successfully updated.'
else
render action: 'edit'
end
end
def destroy
#pin.destroy
redirect_to pins_url
end
private
# Use callbacks to share common setup or constraints between actions.
def set_pin
#pin = Pin.find(params[:id])
end
def correct_user
#pin = current_user.pins.find(params[:id])
redirect_to pins_path, notice: "Not allowed!" if #pin.nil?
end
# Never trust parameters from the scary internet, only allow the white list through.
def pin_params
params.require(:pin).permit(:description)
end
end
Here is are my associations, pin.rb
class Pin < ApplicationRecord
belongs_to :user
end
And my associations for User.rb:
class User < ApplicationRecord
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
has_many :pins
end
and my routes
Rails.application.routes.draw do
resources :pins
devise_for :users
root "pages#home"
get "about" => "pages#about"
end

Answer 1

irb does not automatically load your Rails environment, which is why it does not have access to your models (or helpers, or database, or anything else). However, the "rails console" is an irb session that does load all of your Rails classes, database connections, etc.
To start the rails console:
rails c
Which is shorthand for:
rails console
This starts the rails console for your development environment. You can make it connect to your test environment:
rails c RAILS_ENV=test
or to your production environment:
rails c RAILS_ENV=production