20201110161157_create_pets.rb

class CreatePets < ActiveRecord::Migration[6.0]
  def change
    create_table :pets do |t|
      t.string :address
      t.string :species
      t.date :found_on

      t.timestamps
    end
  end
end

20201110161759_add_address_to_pets.rb

class AddAddressToPets < ActiveRecord::Migration[6.0]
  def change
    add_column :pets, :name, :string
  end
end

_form.html.erb

<%= form_for(animal) do |f| %>
  <%= f.label :name %>
  <%= f.text_field :name %>
  <br>
  <%= f.label :address %>
  <%= f.text_field :address %>
  <br>
  <%= f.label :species %>
  <%= f.collection_select :species, Pet::SPECIES, :to_s, :to_s %>
  <br>
  <%= f.label :found_on %>
  <%= f.date_select :found_on %>
  <br>
  <%= f.submit %>
<% end %>

application_controller.rb

class ApplicationController < ActionController::Base
end

application_record.rb

class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true
end

edit.html.erb

<%= render "form", animal: @pet %>

index.html.erb

<ul>
  <% @pets.each do |pet| %>
    <li>
      <%= link_to pet.name, pet_path(pet) %>

      <% if pet.species == "dog" %>
        | 🐶
      <% elsif pet.species == "cat" %>
        | 😸
      <% end %>

      <% if pet.found_on && pet.address %>
       | <%= pet.found_on %> at <%= pet.address %>
      <% end %>

      | <%= link_to "👨‍👩‍👦", pet_path(pet), method: :delete %>

    </li>
  <% end %>
</ul>

new.html.erb

<%= render "form", animal: @pet %>

pet.rb

class Pet < ApplicationRecord
  SPECIES = ["dog", "cat", "bird", "dolphin"]
  validates :name, presence: true
  validates :species, inclusion: { in: SPECIES }
end

pets_controller.rb

class PetsController < ApplicationController
  before_action :set_pet, only: [:show, :edit, :update, :destroy]

  def index
    @pets = Pet.all
  end

  def show
  end

  def new
    @pet = Pet.new
  end

  def create
    @pet = Pet.new(pet_params)
    @pet.save
    redirect_to root_path
  end

  def edit
  end

  def update
    @pet.update(pet_params)
    redirect_to pet_path(@pet)
  end

  def destroy
    @pet.destroy
    redirect_to root_path
  end

  private

  def set_pet
    @pet = Pet.find(params["id"])
  end

  def pet_params
    params.require(:pet).permit(:name, :species, :address, :found_on)
  end
end

routes.rb

Rails.application.routes.draw do
  root to: "pets#index"
  resources :pets
end

show.html.erb

<h2> <%= @pet.name %> </h2>

<% if @pet.species == "dog" %>
🐶
<% end %>

<% if @pet.found_on && @pet.address %>
  <%= @pet.found_on %> at <%= @pet.address %>
<% end %>