Question

我有一个Customers表和一个Orders表。每个客户都有多个订单。当我做Customers.all.as_json(:include => :orders)时，我得到所有订单，但我只是想得到计数

我尝试了Customers.all.as_json(:include => {:orders => {:only => [], :methods => [:custom_method_to_get_order_count}})虽然它获得了正确的计数，但我有一个对象数组，它等于count。

输出错误！：（

[
  {
    :customer_id => 1,
    :customer_name => "ABC",
    :orders => [
        {:custom_method_to_get_order_count => 2},
        {:custom_method_to_get_order_count => 2}
    ]
  },
  {
    :customer_id => 2,
    :customer_name => "DEF",
    :orders => [
        {:custom_method_to_get_order_count => 3},
        {:custom_method_to_get_order_count => 3},
        {:custom_method_to_get_order_count => 3}
    ]
  },
  {
      :customer_id => 3,
      :customer_name => "XYZ",
      :orders => [
          {:custom_method_to_get_order_count => 10},
          {:custom_method_to_get_order_count => 10},
          {:custom_method_to_get_order_count => 10},
          {:custom_method_to_get_order_count => 10},
          {:custom_method_to_get_order_count => 10},
          {:custom_method_to_get_order_count => 10},
          {:custom_method_to_get_order_count => 10},
          {:custom_method_to_get_order_count => 10},
          {:custom_method_to_get_order_count => 10},
          {:custom_method_to_get_order_count => 10}
      ]
  }
]

正在寻找正确的输出

[
  {
    :customer_id => 1,
    :customer_name => "ABC",
    :orders => {
        :custom_method_to_get_order_count => 2
    }
  },
  {
    :customer_id => 2,
    :customer_name => "DEF",
    :orders => {
        :custom_method_to_get_order_count => 3
    }
  },
  {
      :customer_id => 3,
      :customer_name => "XYZ",
      :orders => {
        :custom_method_to_get_order_count => 10
      }
  }
]

Answer 1

你也可以这样使用：

class Customers

  def get_orders_count
    self.orders.count
  end

end

现在您可以在客户对象中获得所有订单数：

Customers.all.as_json(method: :get_orders_count)

输出类似于：

[
  {
    :customer_id => 1,
    :customer_name => "ABC",
    :get_orders_count => 12
  },
  {
    :customer_id => 2,
    :customer_name => "DEF",
    :get_orders_count => 20
  },
  {
      :customer_id => 3,
      :customer_name => "XYZ",
      :get_orders_count => 50
  }
]

Answer 2

没关系！我得到了答案。

class Customers

  def custom_method_to_get_order_count
    Orders.where(:customer_id => id).count
  end

end

发生了什么事，每当我在SO上发布问题时，我都会得到答案！

在as_json方法

2 个答案: