Question

See Update’s 1 & 2 below for Solution

I’ve been following the tutorial on creating a shopping cart from the book “Agile Web Development with Rails”..They have the chapter I’ve been following here: http://media.pragprog.com/titles/rails4/cart.pdf

In the book they have you create a line_item that get’s passed to a cart and stored in the session by using this line <%= button_to ‘Add to Cart’, line_items_path(product_id: product) %> This in my case would obviously be changed to <%= button_to ”, line_items_path(gear_id: gear), id: ‘rent_it’ %>

If I want to change this so it’s a form that also accepts other parameters how would I do this?

Below is my code that I’ve used and attempted to accomplish this but so far unsuccessfully.
With the below code I get and error that can’t find gear without ‘id’. I’m new to rails and programming in general so I appreciate the help.

UPDATE 1 (I updated my View below as well)

I can now see from my server logs that I’m passing the ID of the Gear in the form. Which is what I was originally trying to do.

Processing by LineItemsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"0QnJShABOV+avPx0AJHxuMmskfwtwFlkpMa6cBhTU3s=", "line_item"=>{"rentstart"=>"", "rentend"=>"", "gear_id"=>"13"}, "commit"=>""}
  Cart Load (0.4ms)  SELECT `carts`.* FROM `carts` WHERE `carts`.`id` = 18 LIMIT 1
Completed 500 Internal Server Error in 2ms

ActiveRecord::RecordNotFound (Couldn't find Gear without an ID):
  app/controllers/line_items_controller.rb:44:in `create'

I’m still getting the error Couldn’t find Gear without an ID. Which are the 2 lines below:

    gear = Gear.find(params[:gear_id])
    @line_item = @cart.add_gear(gear.id)

What am I missing?

Line Item’s Controller

  def create
    @cart = current_cart
    gear = Gear.find(params[:gear_id])
    @line_item = @cart.add_gear(gear.id)

    respond_to do |format|
      if @line_item.save
        format.html { redirect_to @line_item.cart }
        format.json { render json: @line_item, status: :created, location: @line_item }
      else
        format.html { render action: "new" }
        format.json { render json: @line_item.errors, status: :unprocessable_entity }
      end
    end
  end

Cart Model

class Cart < ActiveRecord::Base
  has_many :line_items, dependent: :destroy

  def add_gear(gear_id)
    current_item = line_items.find_by_gear_id(gear_id)
    if current_item
      current_item.quantity += 1
    else
      current_item = line_items.build(params[:line_item])
    end
    current_item
  end

  def total_price
    line_items.to_a.sum { |item| item.total_price }
  end

end

View from Gear Show Page

<div class="gearside_date_main">
        <h3>Rental Date</h3>
        <script>
        $(function() {
            var dates = $( "#rentstart, #rentend" ).datepicker({
                defaultDate: "+1w",
                changeMonth: true,
                numberOfMonths: 1,
                onSelect: function( selectedDate ) {
                    var option = this.id == "rentstart" ? "minDate" : "maxDate",
                        instance = $( this ).data( "datepicker" ),
                        date = $.datepicker.parseDate(
                            instance.settings.dateFormat ||
                            $.datepicker._defaults.dateFormat,
                            selectedDate, instance.settings );
                    dates.not( this ).datepicker( "option", option, date );
                }
            });
        });
        </script>


    <%= form_for LineItem.new do |f| %>
        <%= f.text_field :rentstart, id: 'rentstart'  %>
        <%= f.text_field :rentend, id: 'rentend'  %>
        <%= f.hidden_field :gear_id, :value => @gear.id %>
        <%= f.submit "", id: 'rent_it' %>
    <% end %>
        <% end %>
    </div>

UPDATE 2

I finally got it working after Murifox’s comments. I didn’t completely understand how the syntax is structured when passing a hash. So after much trial and error it is working. I’m including my updated code below to see the changes that I made. I know when I see answers I’m always looking for the change. I hope this helps someone else….

The View (Gear Show Page

<%= form_for LineItem.new do |f| %>
    <%= f.text_field :rentstart, id: 'rentstart'  %>
<%= f.text_field :rentend, id: 'rentend'  %>
<%= f.hidden_field :gear_id, :value => @gear.id %>
    <%= f.submit "", id: 'rent_it' %>
<% end %>

The Controller (Create Action)

  def create
    @cart = current_cart
    gear = Gear.find(params[:line_item][:gear_id])
    lineitem = params[:line_item]
    @line_item = @cart.add_gear(lineitem, gear.id)

    respond_to do |format|
      if @line_item.save
        format.html { redirect_to @line_item.cart }
        format.json { render json: @line_item, status: :created, location: @line_item }
      else
        format.html { render action: "new" }
        format.json { render json: @line_item.errors, status: :unprocessable_entity }
      end
    end
  end

The Cart Model

  def add_gear(lineitem, gear_id)
    current_item = line_items.find_by_gear_id(gear_id)
    if current_item
      current_item.quantity += 1
    else
      current_item = line_items.build(lineitem)
    end
    current_item
  end

Answer 1

Try using

gear = Gear.find(params[:line_item][:gear_id])