Rails：多步表单上的动态选择未保持选中状态

Posted 2023-05-09

【中文标题】Rails：多步表单上的动态选择未保持选中状态

【英文标题】：Rails: dynamic select on multistep form not keeping selected

【发布时间】：2019-05-25 23:47:44

【问题描述】：

我正在为 Ryan Bates 的Multistep Tutorial #217 使用会话的下订单流程制作多步骤表单。第一步，我有两个选择字段：一个用于国家（土地），一个用于运输服务的动态字段。选择土地后，通过javascript/jQuery将运输服务加载到第二个选择字段中，并通过JS计算总价格。

app/views/orders/_shipping_step.html.erb

<%= f.collection_select(:land_id, Land.all, :id, :name, :prompt => "select a country", :id => 'lands_select') %>
<%= f.select(:shippingservice_id, options_for_select(@shippingservices.collect  |s| [s.name.titleize, s.id, 'data-price' => s.price] , :selected => f.object.shippingservice_id), :prompt => "select a carrier", :id => "shippingservices_select") %>

ajax 脚本

$(document).on("change", "#lands_select", function(event)
  $.ajax(
    url: "/carts/update_shipping/" + event.target.value,
    type: "GET",
  )
);

在多步表单的运输详细信息步骤中，我可以选择一个土地，加载相应的运输选项，我可以选择一个。在进行到付款步骤时，我可以下订单并且一切正常，但如果我想从付款步骤返回到订单步骤来更改某些内容，运输服务选择器会显示land_id = 1 的选项，而土地选择显示选择的国家，例如 id 85。

我将:selected => session[:cart_params] 添加到配送服务选择中，但它似乎不起作用。 :selected => f.object.shippingservice_id 保留优先或标准运输选项，但适用于 Land_id 1。

我怎样才能让它工作？是选择字段还是JS？为什么第二个选择不将选择的土地保留在内存中？

提前谢谢你！

日志：

Started GET "/orders/new" for 127.0.0.1 at Thu Dec 27 22:08:52 +0100 2018
Processing by OrdersController#new as HTML
  Cart Load (0.3ms)  SELECT `carts`.* FROM `carts` WHERE `carts`.`id` = ? LIMIT 1  [["id", 1]]
  Land Load (1.4ms)  SELECT `lands`.* FROM `lands` 
  CartItem Load (0.3ms)  SELECT `cart_items`.* FROM `cart_items` WHERE `cart_items`.`cart_id` = 1
   (0.2ms)  SELECT MAX(`cart_items`.`length`) AS max_id FROM `cart_items` WHERE `cart_items`.`cart_id` = 1
   (0.2ms)  SELECT MAX(`cart_items`.`width`) AS max_id FROM `cart_items` WHERE `cart_items`.`cart_id` = 1
  CACHE (0.0ms)  SELECT `lands`.* FROM `lands` 
  Shippingservice Load (0.6ms)  SELECT `shippingservices`.* FROM `shippingservices` INNER JOIN `zones` ON `zones`.`id` = `shippingservices`.`zone_id` INNER JOIN `lands_zones` ON `lands_zones`.`zone_id` = `zones`.`id` INNER JOIN `lands` ON `lands`.`id` = `lands_zones`.`land_id` WHERE `lands`.`id` = 1 AND (weightmin <= 50 AND weightmax >= 50 AND heightmin <= 3 AND heightmax >= 3 AND shippingservices.shippingcarrier = ‘1’) AND (lengthmax >= 210 AND widthmax >= 149)
  Product Load (0.3ms)  SELECT `products`.* FROM `products` WHERE `products`.`id` = 3 LIMIT 1
  Hero Load (0.2ms)  SELECT `heros`.* FROM `heros` WHERE `heros`.`id` = 18 LIMIT 1
  Rendered orders/_shipping_step.html.erb (13.7ms)
  Rendered orders/new.html.erb within layouts/application (16.2ms)
  Rendered layouts/_header.html.erb (0.1ms)
  Rendered layouts/_footer.html.erb (0.1ms)
Completed 200 OK in 44ms (Views: 23.0ms | ActiveRecord: 3.9ms)

选择发货国家：

Started GET "/carts/update_shipping/85" for 127.0.0.1 at Thu Dec 27 22:09:27 +0100 2018
Processing by CartsController#update_shipping as */*
  Parameters: "id"=>"85"
  Cart Load (0.2ms)  SELECT `carts`.* FROM `carts` WHERE `carts`.`id` = ? LIMIT 1  [["id", 1]]
  Land Load (66.9ms)  SELECT `lands`.* FROM `lands` 
  CartItem Load (0.4ms)  SELECT `cart_items`.* FROM `cart_items` WHERE `cart_items`.`cart_id` = 1
   (0.2ms)  SELECT MAX(`cart_items`.`length`) AS max_id FROM `cart_items` WHERE `cart_items`.`cart_id` = 1
   (0.2ms)  SELECT MAX(`cart_items`.`width`) AS max_id FROM `cart_items` WHERE `cart_items`.`cart_id` = 1
  Shippingservice Load (0.6ms)  SELECT `shippingservices`.* FROM `shippingservices` INNER JOIN `zones` ON `zones`.`id` = `shippingservices`.`zone_id` INNER JOIN `lands_zones` ON `lands_zones`.`zone_id` = `zones`.`id` INNER JOIN `lands` ON `lands`.`id` = `lands_zones`.`land_id` WHERE `lands`.`id` = 85 AND (weightmin <= 50 AND weightmax >= 50 AND heightmin <= 3 AND heightmax >= 3 AND shippingservices.shippingcarrier = ‘1’) AND (lengthmax >= 210 AND widthmax >= 149)
  Rendered carts/_shippingservice.html.erb (0.2ms)
  Rendered carts/update_shipping.js.erb (2.9ms)
Completed 200 OK in 87ms (Views: 7.8ms | ActiveRecord: 68.6ms)

进入下一步：

Started POST "/orders" for 127.0.0.1 at Thu Dec 27 22:09:33 +0100 2018
Processing by OrdersController#create as HTML
  Parameters: "order"=>"ship_to_last_name"=>”surname”, "ship_to_address"=>”street”, "ship_to_city"=>”city”, "ship_to_postal_code"=>”postcode”, "phone_number"=>”somenumber”, "shippingservice_id"=>"27", "email"=>”[e-mail]”, "land_id"=>"85", "ship_to_first_name"=>”firstname”, "authenticity_token"=>”somestring”, "utf8"=>"✓", "commit"=>"Continue"
  Cart Load (0.2ms)  SELECT `carts`.* FROM `carts` WHERE `carts`.`id` = ? LIMIT 1  [["id", 1]]
  Land Load (1.5ms)  SELECT `lands`.* FROM `lands` 
  CartItem Load (0.4ms)  SELECT `cart_items`.* FROM `cart_items` WHERE `cart_items`.`cart_id` = 1
   (0.2ms)  SELECT MAX(`cart_items`.`length`) AS max_id FROM `cart_items` WHERE `cart_items`.`cart_id` = 1
   (0.2ms)  SELECT MAX(`cart_items`.`width`) AS max_id FROM `cart_items` WHERE `cart_items`.`cart_id` = 1
  Land Load (0.4ms)  SELECT `lands`.* FROM `lands` WHERE `lands`.`id` = 85 LIMIT 1
  Shippingservice Load (0.3ms)  SELECT `shippingservices`.* FROM `shippingservices` WHERE `shippingservices`.`id` = 27 LIMIT 1
  Product Load (0.3ms)  SELECT `products`.* FROM `products` WHERE `products`.`id` = 3 LIMIT 1
  Hero Load (0.3ms)  SELECT `heros`.* FROM `heros` WHERE `heros`.`id` = 18 LIMIT 1
  Rendered orders/_payment_step.html.erb (7.0ms)
  Rendered orders/new.html.erb within layouts/application (8.9ms)
  Rendered layouts/_header.html.erb (0.1ms)
  Rendered layouts/_footer.html.erb (0.0ms)
Completed 200 OK in 39ms (Views: 13.7ms | ActiveRecord: 4.6ms)

返回发货详情步骤：

Started POST "/orders" for 127.0.0.1 at Thu Dec 27 22:09:35 +0100 2018
Processing by OrdersController#create as HTML
  Parameters: "authenticity_token"=>”somestring”, "utf8"=>"✓", "back_button"=>"Back"
  Cart Load (0.3ms)  SELECT `carts`.* FROM `carts` WHERE `carts`.`id` = ? LIMIT 1  [["id", 1]]
  Land Load (2.4ms)  SELECT `lands`.* FROM `lands` 
  CartItem Load (0.5ms)  SELECT `cart_items`.* FROM `cart_items` WHERE `cart_items`.`cart_id` = 1
   (0.3ms)  SELECT MAX(`cart_items`.`length`) AS max_id FROM `cart_items` WHERE `cart_items`.`cart_id` = 1
   (0.4ms)  SELECT MAX(`cart_items`.`width`) AS max_id FROM `cart_items` WHERE `cart_items`.`cart_id` = 1
  CACHE (0.0ms)  SELECT `lands`.* FROM `lands` 
  Shippingservice Load (0.7ms)  SELECT `shippingservices`.* FROM `shippingservices` INNER JOIN `zones` ON `zones`.`id` = `shippingservices`.`zone_id` INNER JOIN `lands_zones` ON `lands_zones`.`zone_id` = `zones`.`id` INNER JOIN `lands` ON `lands`.`id` = `lands_zones`.`land_id` WHERE `lands`.`id` = 1 AND (weightmin <= 50 AND weightmax >= 50 AND heightmin <= 3 AND heightmax >= 3 AND shippingservices.shippingcarrier = ‘1’) AND (lengthmax >= 210 AND widthmax >= 149)
  Product Load (0.3ms)  SELECT `products`.* FROM `products` WHERE `products`.`id` = 3 LIMIT 1
  Hero Load (0.2ms)  SELECT `heros`.* FROM `heros` WHERE `heros`.`id` = 18 LIMIT 1
  Rendered orders/_shipping_step.html.erb (16.5ms)
  Rendered orders/new.html.erb within layouts/application (18.4ms)
  Rendered layouts/_header.html.erb (0.2ms)
  Rendered layouts/_footer.html.erb (0.1ms)
Completed 200 OK in 109ms (Views: 24.0ms | ActiveRecord: 5.1ms)

更新

这是我orders_controller.rb的部分

before_filter :initialize_cart

def new
  session[:order_params] ||= 
  @order = Order.new(session[:order_params])
  @order.current_step = session[:order_step]
  @shippingservices = @cart.available_shipping_services.joins(:lands).where(:lands => :id => session[:cart_params])
end

def create
  session[:order_params].deep_merge!(params[:order]) if params[:order]
  @order = Order.new(session[:order_params])
  @shippingservices = @cart.available_shipping_services.joins(:lands).where(:lands => :id => session[:cart_params])
  @order.current_step = session[:order_step]
  if @order.valid?
    if params[:back_button]
      @order.previous_step
    elsif @order.last_step? && params[:commit] == 'Option A'
      …
    elsif @order.last_step? && params[:commit] == 'Option B'
      …
    else
      @order.next_step
    end
    session[:order_step] = @order.current_step
  end
  if @order.new_record?
    render "new"
  else
    # Empty the cart
    @cart.cart_items.destroy_all
    # Reset session
    session[:order_step] = session[:order_params] = nil
  end
end

当我通过 Land.first.id 或 Land.last.id 指定 id 时，查询有效，后退步骤似乎有效。

当使用session[:order_params] 时，我得到ActiveRecord::StatementInvalid in Orders#create 但正确的land_id 存在：

mysql::Error: Unknown column 'id.ship_to_last_name' in 'where clause': SELECT `shippingservices`.* FROM `shippingservices` 
INNER JOIN `zones` ON `zones`.`id` = `shippingservices`.`zone_id` 
INNER JOIN `lands_zones` ON `lands_zones`.`zone_id` = `zones`.`id` 
INNER JOIN `lands` ON `lands`.`id` = `lands_zones`.`land_id` 
WHERE `id`.`ship_to_last_name` = 'Smith' 
AND `id`.`ship_to_address` = 'Somewherestreet' 
AND `id`.`ship_to_city` = 'Nowheretown' 
AND `id`.`ship_to_postal_code` = '99999' 
AND `id`.`phone_number` = 'some number' 
AND `id`.`shippingservice_id` = '34' 
AND `id`.`email` = '[e-mail]' 
AND `id`.`land_id` = '85' 
AND `id`.`ship_to_first_name` = 'John' 
AND (weightmin <= 200 AND weightmax >= 200 AND heightmin <= 12 AND heightmax >= 12 AND shippingservices.shippingcarrier = '1') AND (lengthmax >= 210 AND widthmax >= 149)

【问题讨论】：

你能把OrdersController的代码贴出来吗？在后面的步骤中，Shippingservice Load 正在运行具有WHERE lands.id = 1 的查询。也许这是未定义的@land 变量的后备？

感谢您的回复。从昨天开始，我一直在做这件事。 WHERE lands.id = 1 可能是某种后备。据我所知，params[:id] 应该是不可能的，因为我还没有提交，也没有任何东西写入数据库。我猜想我需要从 orders_params 中提供 id.land_id 值。

您为什么要调用session[:cart_params] 来获取land_id 而不是从session[:order_params] 中获取它？旁注：‘Option A’ 和 B 那些引号很奇怪，需要改成普通引号。

session[:order_params][:land_id] 也许？您应该能够查看会话的结构并从中获取价值

@order.land_id 或者它有什么关系怎么样？然后你将它从新初始化的@order 中拉出来，而不是依赖会话。

【参考方案1】：

@shippingservices = @cart.available_shipping_services.joins(:lands).where(:lands => :id => session[:cart_params])

这未正确使用session[:cart_params] 获取land_id 以便在通过表单返回时设置订单登陆。我们可以改为使用上面定义的@order = Order.new(session[:order_params]) 来获取@order.land_id，而不必依赖任何会话。

如果有可能在没有相应土地的情况下初始化订单，我还会添加一个存在检查。

【讨论】：

感谢您提供非常有用的反馈！