动态生成的带有茧轨道的嵌套形式

Question

我有一个带有cocoon的嵌套表单，但是在尝试从JavaScript计算总价格时遇到问题。当我检查我的视图源页面时，从字段中生成的属性没有值属性。如果我使用@invoice.line_items.build，则计算总价格，但看不到茧的动态字段。谢谢，等待我能尽快得到的任何帮助。

class InvoicesController < ApplicationController
before_action :set_invoice,:set_line_item, only: [:show, :edit, :update, :destroy]
def index
@invoices = Invoice.all
end
def show
end
def new
@invoice = Invoice.new
@invoice.line_items.build
end
# GET /invoices/1/edit
def edit
end
def create
@invoice = Invoice.new(invoice_params)
respond_to do |format|
if @invoice.save
format.html { redirect_to @invoice, notice: 'Invoice was successfully created.' }
format.json { render :show, status: :created, location: @invoice }
else
format.html { render :new }
format.json { render json: @invoice.errors, status: :unprocessable_entity }
end
end
end
def update
respond_to do |format|
if @invoice.update(invoice_params)
format.html { redirect_to @invoice, notice: 'Invoice was successfully updated.' }
format.json { render :show, status: :ok, location: @invoice }
else
format.html { render :edit }
format.json { render json: @invoice.errors, status: :unprocessable_entity }
end
end
end
def destroy
@invoice.destroy
respond_to do |format|
format.html { redirect_to invoices_url, notice: 'Invoice was successfully destroyed.' }
format.json { head :no_content }
end
end

private
# Use callbacks to share common setup or constraints between actions.
def set_invoice
@invoice = Invoice.find(params[:id])
end
def set_line_item
@line_item = LineItem.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.    
def invoice_params
params.require(:invoice).permit(:amount, :date, :currency, {line_items_attributes: 
[:id,:quantity,:net_amount, :description, :unit_cost]})
end
end

---

<tbody class='line_items'>
<%= f.fields_for :line_items do |builder| %>
<%= render 'line_item_fields', :f => builder %>
<% end %> 
</tbody>
</table>
<%= link_to_add_association 'add item', f, :line_items, class: "btn btn- 
primary",data: {"association-insertion-node" => "tbody.line_items", "association-insertion-method" => "append"} %>
<%= f.submit  class:"btn btn-primary" %>

---

<tr class="nested-fields">
<div class="container">
<div class="row row-cols-5">
<div class="col"> <td><%= f.text_field :description, class: "form-control item_desc" %></td></div><br/>
<div class="col"> <td><%= f.text_field :quantity,  class: "form-control quantity" %></td></div><br/>
<div class="col"> <td><%= f.text_field :unit_cost, class: "form-control unit_cost"%></td></div><br/>
<div class="col"> <td class="price_td"><%= f.text_field  :net_amount, class: "form-control price", :readonly => true %></span> <span class= "subtotal_currency"></span></td></div><br/>
<div class="col"> <td><%= link_to_remove_association 'Delete', f, class: 'remove_record btn btn-danger' %></td></div>
</div>
</div>

这是JavaScript

function update_price(){ 
var row = $(this).parents('.nested-fields');
var price = row.find('.unit_cost').val() * row.find('.quantity').val();
price = price.toFixed(2);
isNaN(price) ? row.find('.price').val('is not a number') : 
row.find('.price').val(price);
update_subtotal();
}

Answer 1

使用以下代码附加事件：

$('.unit_cost').blur(update_price); 
$('.quantity').blur(update_price); 

但是，这只会在运行此命令时将事件处理程序绑定到页面上的元素，并且有更好的实现相同目的的方法：

$(document).on('blur', '.unit_cost, .quantity', update_price)

我将事件附加到顶级document(因此这甚至是turbolinks兼容的，但您也可以使用封闭form或div(，我们响应blur事件，但前提是触发元素具有类.unit_cost或.quantity。