ruby-on-rails - ActiveRecord sum 和 pluck 方法返回奇怪的值

Question

我有订单模型和 Order.all下面返回。

[
[0] #<Order:0x007f9d9e236de0> {
              :id => 15,
         :user_id => 2,
       :artist_id => nil,
      :address_id => 18,
         :paid_at => nil,
    :payment_type => "bank",
            :guid => "c8e22764774adc6825348b8874b581e8",
      :created_at => Mon, 24 Aug 2015 19:42:09 JST +09:00,
      :updated_at => Mon, 24 Aug 2015 19:45:38 JST +09:00,
      :ordered_at => Mon, 24 Aug 2015 19:45:37 JST +09:00,
           :total => 43890
},
[1] #<Order:0x007f9d9e2367a0> {
              :id => 12,
         :user_id => 2,
       :artist_id => nil,
      :address_id => 18,
         :paid_at => nil,
    :payment_type => "bank",
            :guid => "274b4a8653395023125a4724139efc09",
      :created_at => Mon, 24 Aug 2015 19:10:38 JST +09:00,
      :updated_at => Mon, 24 Aug 2015 19:41:25 JST +09:00,
      :ordered_at => Mon, 24 Aug 2015 19:41:22 JST +09:00,
           :total => 48689
},
[2] #<Order:0x007f9d9e236318> {
              :id => 11,
         :user_id => 2,
       :artist_id => nil,
      :address_id => 14,
         :paid_at => Mon, 24 Aug 2015 19:10:38 JST +09:00,
    :payment_type => "credit_card",
            :guid => "b075f4a6f31c32942152f7d50d2bd098",
      :created_at => Mon, 24 Aug 2015 19:03:39 JST +09:00,
      :updated_at => Mon, 24 Aug 2015 19:10:38 JST +09:00,
      :ordered_at => Mon, 24 Aug 2015 19:10:38 JST +09:00,
           :total => 5010
},
[3] #<Order:0x007f9d9e235e40> {
              :id => 10,
         :user_id => nil,
       :artist_id => nil,
      :address_id => nil,
         :paid_at => nil,
    :payment_type => nil,
            :guid => "916ff17977cb176c5e5740faab92a08c",
      :created_at => Sat, 22 Aug 2015 19:30:38 JST +09:00,
      :updated_at => Sat, 22 Aug 2015 19:30:38 JST +09:00,
      :ordered_at => nil,
           :total => 0
},
[4] #<Order:0x007f9d9e2356c0> {
              :id => 9,
         :user_id => 1,
       :artist_id => nil,
      :address_id => 9,
         :paid_at => nil,
    :payment_type => "bank",
            :guid => "a4f1dd11ad035d1747a37776b062021f",
      :created_at => Sat, 22 Aug 2015 19:30:04 JST +09:00,
      :updated_at => Tue, 01 Sep 2015 00:00:09 JST +09:00,
      :ordered_at => Sat, 22 Aug 2015 00:00:00 JST +09:00,
           :total => 5010
},
[5] #<Order:0x007f9d9e2342c0> {
              :id => 8,
         :user_id => 1,
       :artist_id => nil,
      :address_id => 9,
         :paid_at => Thu, 20 Aug 2015 19:30:04 JST +09:00,
    :payment_type => "credit_card",
            :guid => "b816503b6b95d35455262cd4d8b9e822",
      :created_at => Sat, 22 Aug 2015 19:30:04 JST +09:00,
      :updated_at => Sat, 22 Aug 2015 19:30:04 JST +09:00,
      :ordered_at => Wed, 19 Aug 2015 19:30:04 JST +09:00,
           :total => 0
}

]

然而， Order.sum(:total)返回

Order.sum(:total)
(0.4ms)  SELECT SUM("orders"."total") FROM "orders"
12000

和 Order.pluck(:total)返回

Order.pluck(:total)
CACHE (0.0ms)  SELECT "orders"."total" FROM "orders"  ORDER BY   "orders"."created_at" DESC
[
    [0] nil,
    [1] nil,
    [2] nil,
    [3] nil,
    [4] 2000,
    [5] 10000
]

所以发生了什么事？
我怎样才能获得正确的值(value)？

感谢许多评论。

我有默认范围，但只有订单，

   default_scope { order(created_at: :desc) }

.这会影响这个问题吗？？

这是“Order.all”查询。

Order Load (1.0ms) SELECT "orders".* FROM "orders" ORDER BY "orders"."created_at" DESC 
Item Load (0.4ms) SELECT "items".* FROM "items" WHERE "items"."order_id" = $1 [["order_id", 20]] 
Flower Load (0.7ms) SELECT "flowers".* FROM "flowers" WHERE "flowers"."type" IS NULL AND "flowers"."item_id" = $1 ORDER BY "flowers"."created_at" ASC LIMIT 1 [["item_id", 8]]   

Order.all.map(&:total)返回

[ [ 0] 43890, [ 1] 48689, [ 2] 5010, [ 3] 0, [ 4] 5010, [ 5] 0 ] 

抱歉回复延迟...

这是我对 orders.html.erb 的结果，
我只使用 myapp_development 和 myapp_test 数据库。

Order.count 6
Order.sum(:total)   12,000
Order.pluck(:total) [nil, nil, 2000, 10000, nil, nil]
Order.all.map(&:total)  [0, 5010, 0, 0, 16110, 0]
#<Order id: 6, user_id: 1, artist_id: nil, address_id: nil, paid_at: nil, payment_type: nil, guid: "a6471c15680a0fbcd3f515a1bdf83566", created_at: "2015-09-02 07:24:37", updated_at: "2015-09-02 07:24:37", ordered_at: nil, total: nil, conveni_name: nil, conveni_code: nil, invoice_id: nil>

#<Order id: 5, user_id: 1, artist_id: nil, address_id: 14, paid_at: "2015-09-02 07:24:36", payment_type: 0, guid: "b68989c73bc0af34e3eef56abbcb306c", created_at: "2015-09-01 08:58:07", updated_at: "2015-09-02 07:24:36", ordered_at: "2015-09-02 07:24:36", total: nil, conveni_name: nil, conveni_code: nil, invoice_id: nil>

#<Order id: 4, user_id: 1, artist_id: nil, address_id: 1, paid_at: nil, payment_type: 2, guid: "1863cc6f2884b88598c4524d564b8a4a", created_at: "2015-09-01 06:07:52", updated_at: "2015-09-01 06:07:52", ordered_at: "2015-08-31 15:00:00", total: 2000, conveni_name: nil, conveni_code: nil, invoice_id: nil>

#<Order id: 3, user_id: 1, artist_id: nil, address_id: 1, paid_at: "2015-08-30 06:07:52", payment_type: 0, guid: "a6f7e22fc9ea8bdccdbdcbb00d9ea250", created_at: "2015-09-01 06:07:52", updated_at: "2015-09-01 06:07:52", ordered_at: "2015-08-29 06:07:52", total: 10000, conveni_name: nil, conveni_code: nil, invoice_id: nil>

#<Order id: 2, user_id: 1, artist_id: nil, address_id: 11, paid_at: "2015-09-01 08:58:06", payment_type: 0, guid: "f29dd23315078fce2e5b38e16d027c45", created_at: "2015-09-01 06:06:33", updated_at: "2015-09-01 08:58:06", ordered_at: "2015-09-01 08:58:06", total: nil, conveni_name: nil, conveni_code: nil, invoice_id: nil>

#<Order id: 1, user_id: nil, artist_id: nil, address_id: nil, paid_at: nil, payment_type: nil, guid: "6f2ffd0e8ba491fba10d69b73e717384", created_at: "2015-09-01 03:08:44", updated_at: "2015-09-01 03:08:44", ordered_at: nil, total: nil, conveni_name: nil, conveni_code: nil, invoice_id: nil>

Answer 1

您提供的信息自相矛盾。

我想你看不同的数据库。

让我解释一下我为什么这么认为。

事实 #1 基于 Order.all我们有输出:

#<Order id: 15, total: 43890.0>
#<Order id: 12, total: 48689.0>
#<Order id: 11, total: 5010.0>
#<Order id: 10, total: 0.0>
#<Order id: 9,  total: 5010.0>
#<Order id: 8,  total: 0.0>

total这里的属性与数据库中写入的相同。即使您在 Order 中定义了同名的方法模型，此属性不应受其影响。

事实#2 基于 Order.pluck(:total)我们有输出:

#<Order id: 15, total: nil>
#<Order id: 12, total: nil>
#<Order id: 11, total: nil>
#<Order id: 10, total: nil>
#<Order id: 9,  total: 2000>
#<Order id: 8,  total: 10000>

再次， total这里的属性与数据库中写入的相同。同样，它不受模型中定义的方法的影响。

现在我们看到 事实 1 矛盾 事实 2 .我几乎可以肯定您在这里查看的是不同的数据库。

确保您不会得到矛盾结果的最佳方法是创建一个包含以下内容的新页面:

<!-- orders.html.erb -->

<table>
  <tr>
    <td>Order.count</td>
    <td><%= Order.count %></td>
  </tr>
  <tr>
    <td>Order.sum(:total)</td>
    <td><%= number_with_delimiter Order.sum(:total) %></td>
  </tr>
  <tr>
    <td>Order.pluck(:total)</td>
    <td><%= Order.pluck(:total) %></td>
  </tr>
  <tr>
    <td>Order.all.map(&amp;:total)</td>
    <td><%= Order.all.map(&:total) %></td>
  </tr>
</table>

<% Order.all.each do |o| %>
  <p>
    <code><%= o.inspect %></code>
  </p>
<% end %>

并为我们提供此页面的输出以供进一步探索。

基本上我要求的是:

检查您是否在使用两个不同的数据库

如果#1 没有用，请使用给定的 ERB 模板创建一个新操作并共享它的输出。