Rails forms

book.rb

class Book < ActiveRecord::Base
  validates :name, :presence => true
  validates :published_at, :presence => true
end

books_controller.rb

class BooksController < ApplicationController
  def index
    @books = Book.all
    @book = Book.new
  end

  def show
    @book = Book.find params[:id]
  end

  def create
    book = Book.new(book_params)
    if book.save
      # Redirect to the new book's show page
      redirect_to "/books/#{book.id}"
    else
      @book = book
      @books = Book.all
      render 'index'
    end
    
  end

  def edit
    @book = Book.find params[:id]   
  end

  def book_params
    params.require(:book).permit(:name, :published_at)
  end

  def update
  end
  def destroy
  end
end

index.html.erb

<h2>New Book</h2>
<% if @book.errors.any? %>
    <p><%= @book.errors.messages.inspect %></p>
<% end %>

<%= form_tag("/books", method: "post") do %>
  <%= label_tag('book[name]', "Title:") %>
  <%= text_field_tag('book[name]', @book.name) %><br>
  
  <%= label_tag('book[published_at]', "Published:") %>
  <%= date_field_tag('book[published_at]', @book.published_at) %><br>

  <%= submit_tag("submit") %>
<% end %>

<h2>All Books:</h2>

<% @books.each do |book| %>
    <p>
<%= link_to book.name, "/books/#{book.id}" %>
    </p>

<% end %>

routes.rb

Rails.application.routes.draw do
  get '/' => 'books#index'
  get 'books/:id' => 'books#show'
  post '/books' => 'books#create'
end

show.html.erb

<h1><%= @book.name %></h1>
<p>Published at: <%= @book.published_at %></p>