ruby - Rails connect modal with a create action -

it's first post. i'm new in rails , need help. try make online shop. have create button "buy" (with bootstrap) under each of products, activate modal. inside modal button "add cart", , cant make work. want through create action in line_items_controller add line_item cart. modal works fine button "add cart" no. think problem path give button.

my code:

cart.rb

class cart < activerecord::base   has_many :line_items, dependent: :destroy 

line_item.rb

class lineitem < activerecord::base   belongs_to :product       belongs_to :cart 

product.rb

class product < activerecord::base   has_many :line_items 

line_items_controller.rb

class lineitemscontroller < applicationcontroller   include currentcart   before_action :set_cart, only: [:create]   before_action :set_line_item, only: [:show, :edit, :update, :destroy]         def create             @product = product.find(params[:product_id])             @line_item = create_line_items(@product)             respond_to |format|               if @line_item.save                 format.html { redirect_to @line_item.cart, notice: 'line item created.' }                 format.json { render :show, status: :created, location: @line_item }               else                 format.html { render :new }                 format.json { render json: @line_item.errors, status: :unprocessable_entity }               end             end           end        private         def set_line_item           @line_item = lineitem.find(params[:id])         end          def line_item_params           params.require(:line_item).permit(:product_id, :cart_id)         end 

app/controllers/concerns/current_cart.rb

module currentcart   extend activesupport::concern    def create_line_items(product)      @cart.line_items.build(product: product)   end  private    def set_cart      @cart = cart.find(session[:cart_id])     rescue activerecord::recordnotfound     @cart = cart.create     session[:cart_id] = @cart.id   end end 

the modal in application.html.erb

<div class="modal fade" id="buymodal" role="dialog">     <div class="modal-dialog">         <div class="modal-content">             <div class="modal-body">                 <p>are sure want buy this?</p>                  <%= button_to 'add cart', line_items_path(product_id: @product), :class => "btn btn-success glyphicon glyphicon-plus", data: {dismiss: "modal"} %>             </div>         </div>     </div> </div> 

and button 'buy' trigger modal.

views/products/index.html.erb

<%= link_to 'buy', '#', class: "btn btn-success active", data: { toggle: "modal", target: "#buymodal"}  %> 

i appreciate help!

the problem seems me method type. try use ':method => :post' button_to tag.

<%= button_to 'add cart', line_items_path(product_id: @product), :method => :post, :class => "btn btn-success glyphicon glyphicon-plus", data: {dismiss: "modal"} %>