Ruby on rails 当尝试创建新实例时，它将'；s正在丢失执行此操作所需的关联参数

轨道5.1.6

我有一个应用程序，上面列出了产品，你可以在订单中添加一定数量的产品。好吧，这就是我的想法。所以，现在我有一个表单来获取数量，还获取产品id和订单id，通过order_items表将它们关联起来，order_items表也保存了数量。看起来表单正在抓取order\u id并在order\u items参数中进行设置。在这种情况下，5。db中不存在id为5的订单。当参数传递给.new时，它传递的是一个空白id？我错过了什么

ActiveRecord:：RecordNotFound（找不到id为的订单）： 表格雇员再培训局

<% @products.each do |product| %>
<div class="col s4">

  <h4><%= link_to product.name, product_path(product) %></h4>

  <%= form_for @order_item do |f| %>
    <%= f.hidden_field :order_id, value: @order.id %>
    <%= f.hidden_field :product_id, value: product.id %>
    <%= f.number_field :quantity, placeholder: "quantity" %>

    <span class="waves-effect waves-light btn"><%= f.submit "Add to order" %></span>

  <% end %>
</div>

终点站

Started POST "/order_items" for 127.0.0.1 at 2018-06-06 16:50:31 -0700
Processing by OrderItemsController#create as JS
Parameters: {"utf8"=>"✓", "order_item"=>{"order_id"=>"5", 
"product_id"=>"2", "quantity"=>""}, "commit"=>"Add to order"}
Order Load (0.2ms)  SELECT  "orders".* FROM "orders" WHERE 
"orders"."id" = $1 LIMIT $2  [["id", nil], ["LIMIT", 1]]
Completed 404 Not Found in 2ms (ActiveRecord: 0.2ms)

ActiveRecord::RecordNotFound (Couldn't find Order with 'id'=):

app/controllers/order_items_controller.rb:4:in `create'

在这里：

您正在通过

参数[：id]

进行查找。但是你看

Parameters: {"utf8"=>"✓", "order_item"=>{"order_id"=>"5", "product_id"=>"2", "quantity"=>""}, "commit"=>"Add to order"}

无

参数[：id]

。但是，您确实有

参数[：order\u item][：order\u id]

。也许你打算用这个

此外，您还可以简化

创建
操作：

def create
  @order_item = OrderItem.new(item_params)
  if @order_item.save
    flash[:notice] = "Your order has been added!"
    redirect_to orders_path
  else
    render :new
  end
end

假设您的参数中有所有的
order\u项
属性：

"order_item"=>{"order_id"=>"5", "product_id"=>"2", "quantity"=>""}

没有真正的需要去寻找
@订单
（除非你对事物感到紧张）
 您的：创建操作至少有三个问题：

1） 表单中的一个隐藏字段将order_id作为参数传入，您应该使用它来查找顺序，如下所示：

@order = Order.find(params[:order_item][:order_id])

2） 在：create操作中对
@order
实例调用save两次

3） 实际上，您正在对
@order
实例变量调用save，但在任何时候都不保存
@item
实例变量。保存
@order
时是否保存
@item

因此，我将尝试以下方法：

def create
  @order = Order.find(params[:order_item][:order_id])

  # how come you don't save this? You instantiate it but don't appear to call save at any point.
  @item = @order.order_items.new(item_params)

  # remove the following line, which I've commented out:
  # @order.save

  # Consider whether you wish to save @order or @item, or both
  if @order.save
    flash[:notice] = "Your order has been added!"
    redirect_to orders_path
  else
    render :new
  end
end

希望有帮助，祝你好运

@order = Order.find(params[:order_item][:order_id])

def create
  @order = Order.find(params[:order_item][:order_id])

  # how come you don't save this? You instantiate it but don't appear to call save at any point.
  @item = @order.order_items.new(item_params)

  # remove the following line, which I've commented out:
  # @order.save

  # Consider whether you wish to save @order or @item, or both
  if @order.save
    flash[:notice] = "Your order has been added!"
    redirect_to orders_path
  else
    render :new
  end
end