Mysql 有多个关联加载不完整的结果

我有两种型号

class Activity
  has_and_belongs_to_many :photos, -> { where "deleted = false"}
end

class Photo
  has_and_belongs_to_many :activities
end

让我们假设我只有一个活动，它有两张照片

当我尝试加载活动列表并急切加载其相应的照片时，每个活动只返回一张照片

activities = Activity.all.includes(:photos)

a.first.id # => 1
a.first.photos.size   # => 1

相应的SQL查询运行如下

SELECT `activities`.* FROM `activities`
SELECT `activities_photos`.*, `activities_photos`.`activity_id` AS t0_r0, `activities_photos`.`photo_id` AS t0_r1, `photos`.`id` AS t1_r0, `photos`.`primary_photo` AS t1_r1, `photos`.`created_at` AS t1_r2, `photos`.`updated_at` AS t1_r3, `photos`.`deleted` AS t1_r4, `photos`.`url` AS t1_r5, `photos`.`thumbnail_url` AS t1_r6 FROM `activities_photos` LEFT OUTER JOIN `photos` ON `photos`.`id` = `activities_photos`.`photo_id` WHERE (deleted = false) AND `activities_photos`.`activity_id` IN (1)

SELECT `activities`.* FROM `activities`
SELECT `photos`.* FROM `photos` INNER JOIN `activities_photos` ON `photos`.`id` = `activities_photos`.`photo_id` WHERE `activities_photos`.`activity_id` = ? AND (deleted = false)  [["activity_id", 1]]

第二个查询在MYSQL中运行时返回2行

对吗

这就是它变得更加脆弱的地方

我不急于加载“照片”，而是为每个活动单独加载

activities = Activity.all

a.first.id # => 1
a.first.photos.size # => 2

所以这次我得到了所有需要的数据

相应的SQL查询运行如下

SELECT `activities`.* FROM `activities`
SELECT `activities_photos`.*, `activities_photos`.`activity_id` AS t0_r0, `activities_photos`.`photo_id` AS t0_r1, `photos`.`id` AS t1_r0, `photos`.`primary_photo` AS t1_r1, `photos`.`created_at` AS t1_r2, `photos`.`updated_at` AS t1_r3, `photos`.`deleted` AS t1_r4, `photos`.`url` AS t1_r5, `photos`.`thumbnail_url` AS t1_r6 FROM `activities_photos` LEFT OUTER JOIN `photos` ON `photos`.`id` = `activities_photos`.`photo_id` WHERE (deleted = false) AND `activities_photos`.`activity_id` IN (1)

SELECT `activities`.* FROM `activities`
SELECT `photos`.* FROM `photos` INNER JOIN `activities_photos` ON `photos`.`id` = `activities_photos`.`photo_id` WHERE `activities_photos`.`activity_id` = ? AND (deleted = false)  [["activity_id", 1]]

如何通过快速加载获取所有照片

---

我是做错了什么还是有什么奇怪的错误？

将

->{where“deleted=false”}

更改为

->{where（deleted:false）}

；使用

activities=Activity.includes（：照片）.all

；让我知道它是否修复了您的问题活动。包括（：照片）。所有都提供相同的输出。我面临的另一个问题是，更改为{where（deleted:false）}会导致ActiveRecord:：StatementInvalid exception-“where子句中的未知列'photos.deleted'：从

activities\u photos

where

photos

deleted=0和

activities\u photos

activity\u id

中选择

*。”…当我在where条件中使用哈希时，它没有对实际的photos表执行联接。”未知列“photos.deleted”：找到包含
deleted
列的表名，然后将其添加到此处：
->{where（您的表名：{deleted:false}）}
这解决了使用哈希的问题。但仍然只得到第一张照片使用渴望加载。