For my project, I need to create an ‘add to cart’ button that adds the item to cart and directs the user to the cart page (localhost:3030/cart). I have a button created but it is not functioning. I need help. I’m very new to rails so I don’t know much of how to navtigate through it all. I only know the little that I was taught in a couple months in a semester.

Cart Model

class Cart < ApplicationRecord
  has_many :items

  def add_item(prebuilt_id)
    items.find_or_create_by(prebuilt_id: prebuilt_id)
  end

end

Item Model

class Item < ApplicationRecord
  belongs_to :cart
  belongs_to :prebuilt
end

Cart Controller

class CartController < ApplicationController
  def index
    @cart = Prebuilt.all
    render :index
  end

  def show
    @cart = current_cart
   end

   def add_to_cart
    current_cart.add_item(params[:prebuilt_id])
    redirect_to cart_path(current_cart.id)
    flash[:success] = 'Item successfully updated!'
  end

end

Item Controller

class Item < ApplicationRecord
  belongs_to :cart
  belongs_to :prebuilt
end

Prebuilt Controller

class PrebuiltsController < ApplicationController
    before_action :authenticate_user!, except: [:index]
    def index
        @prebuilts = Prebuilt.all
        render :index
    end

    def show
        @prebuilt = Prebuilt.find(params[:id])
        render :show
    end

end

Cart Page

<% content_for(:html_title) { 'Junior Jets | Cart' } %>

<h1 style="font-family:'Courier New'"><b>YOUR CART</b></h1>

<div class="cart">

<style>
  #right {
    text-align: right;
    background-color: #ffffff;
  }
</style>

<table id="line_items">
  <tr>
    <th>Product</th>
    <th>Qty</th>
    <th class="price">Unit Price</th>
    <th class="price">Full Price</th>
  </tr>

  <% for item in @cart %>
    <tr class="<%= cycle :odd, :even %>
       <td><%=h item.name %></td>
    </tr>
   <% end %>
  </tr>
</table>


  <div id="right">
  <div class="totals">
    <div class="totals-item">
      <label>Subtotal</label>
      <div class="totals-value" id="cart-subtotal">71.97</div>
    </div>
    <div class="totals-item">
      <label>Tax (10%)</label>
      <div class="totals-value" id="cart-tax">3.60</div>
    </div>
    <div class="totals-item">
      <label>Shipping</label>
      <div class="totals-value" id="cart-shipping">15.00</div>
    </div>
    <div class="totals-item totals-item-total">
      <label>Grand Total</label>
      <div class="totals-value" id="cart-total">90.57</div>
    </div>
  </div>
  <a href="http://localhost:3000/checkout">
  <button>Checkout</button>
  </a>
  </div>

</div>

Prebuilt Page aka Product Page

<h1>Jets</h1>

<h3> Artistic Jet
<%= image_tag 'artisticplane.jpg',
  class: 'float-start w-50 l-50 rounded-circle shadow-lg d-block mx-auto',
  style: 'max-width: 16rem;',
  loading: 'lazy'
%>
</h3>

<hr>

<h3> Barbie Jet
<%= image_tag 'barbieplane.jpg',
  class: 'float-start w-10 l-10 rounded-circle shadow-lg d-block mx-auto',
  style: 'max-width: 16rem;', loading: 'lazy'
%>
</h3>

<hr>

<h3> Prehistoric Jet
<%= image_tag 'prehistoricplane.jpg',
  class: 'float-start w-50 l-50 rounded-circle shadow-lg d-block mx-auto',
  style: 'max-width: 16rem;',
  loading: 'lazy'
%>
</h3>

<hr>

<h3> Tractor-Themed Jet
<%= image_tag 'tractorplane.jpg',
  class: 'float-start w-50 l-50 rounded-circle shadow-lg d-block mx-auto',
  style: 'max-width: 16rem;',
  loading: 'lazy'
%>
</h3>


<table class="table table-striped table-hover">

  <thead class="table-dark">
    <tr>
      <th>Name</th>
      <th>Description</th>
      <th>Manufacturer</th>
      <th>Color</th>
      <th>Size</th>
      <th>Price</th>
      <th></th>
    </tr>
  </thead>

  <tbody>
    <% @prebuilts.each do |prebuilt| %>
      <tr>
        <td><%= prebuilt.name %></td>
        <td><%= prebuilt.description %></td>
        <td><%= prebuilt.description %></td>
        <td><%= prebuilt.manufacturer %></td>
        <td><%= prebuilt.color %></td>
        <td><%= prebuilt.size %></td>
        <td><%= prebuilt.price %></td>
        <td class="text-nowrap">
          <%= link_to 'show', prebuilt_path(prebuilt), class: 'btn btn-sm btn-outline-secondary' %>
          <td><%= button_to 'add to cart', add_to_cart_path(prebuilt_id: prebuilt), method: :post %></td>
        </td>
      </tr>
    <% end %>
  </tbody>

</table>


<p>
  <%= link_to 'New Jet', new_jet_path, class: 'btn btn-secondary' %>
</p>

Routes

  get 'cart', to: 'cart#index', as: 'cart';

  post '/add_to_cart/:prebuilt_id' => 'cart#add_to_cart', :as => 'add_to_cart'

  get 'checkout', to: 'pages#checkout', as: 'checkout';

  get 'confirm', to: 'pages#confirm', as: 'confirm';

get 'prebuilts', to: 'prebuilts#index', as: 'prebuilts'
  get 'prebuilts/:id', to: 'prebuilts#show', as: 'prebuilt'

Seeds.rb

prebuilt1 = Prebuilt.create!(
  name: "Alfred's Artistic Jet",
  description: "Designed by Alfred",
  manufacturer: "Boeing",
  color: "Mixed",
  size: "Large",
  price: 2999999
)

prebuilt2 = Prebuilt.create!(
  name: "Brittany's Barbie Jet",
  description: "Designed by Brittany",
  manufacturer: "Boeing",
  color: "Pink",
  size: "Large",
  price: 4499999
)

prebuilt3 = Prebuilt.create!(
  name: "Peter's Prehistoric Jet",
  description: "Designed by Peter",
  manufacturer: "Airbus",
  color: "Blue",
  size: "Small",
  price: 7999999
)

prebuilt4 = Prebuilt.create!(
  name: "Tianna's Tractor-Themed Jet",
  description: "Designed by Tianna",
  manufacturer: "Airbus",
  color: "Mixed",
  size: "Large",
  price: 1999999
)