<%= form_tag do %> <% @products.each do |product| %> <%= fields_for "products[]", product do |form| %> <%= image_tag product.avatar %> <%= form.number_field :stock_inc, value: 0, class: 'form-control' %> <% end %> <% end %> <%= submit_tag "Insert stock", class: 'btn btn-primary' %> <% end %>