如何编写Activerecord/Arel交叉查询

Question

我在PSQL中实现了这个功能：

SELECT "profiles".id FROM "profiles"
INNER JOIN "integration_profiles"
ON "integration_profiles"."profile_id" = "profiles"."id"
INNER JOIN "integrations"
ON "integrations"."id" = "integration_profiles"."integration_id"
WHERE "integrations"."provider" = 'csv'
INTERSECT
SELECT "profiles".id FROM "profiles"
INNER JOIN "integration_profiles"
ON "integration_profiles"."profile_id" = "profiles"."id"
INNER JOIN "integrations"
ON "integrations"."id" = "integration_profiles"."integration_id"
WHERE "integrations"."provider" = 'kickstarter'

我想把它转换成ActiveRecord查询或Arel。

我试过：

Arel::Nodes::Intersect.new(
  Profile.joins(:integrations).where(integrations: { provider: 'csv' }),
  Profile.joins(:integrations).where(integrations: { provider: 'kickstarter' })
)

[Debug]   Profile Load (408.2ms)  SELECT "profiles".* FROM "profiles" INNER JOIN "integration_profiles" ON "integration_profiles"."profile_id" = "profiles"."id" INNER JOIN "integrations" ON "integrations"."id" = "integration_profiles"."integration_id" WHERE "integrations"."provider" = 'csv' (pid:65570)
 [Debug]   Profile Load (1.9ms)  SELECT "profiles".* FROM "profiles" INNER JOIN "integration_profiles" ON "integration_profiles"."profile_id" = "profiles"."id" INNER JOIN "integrations" ON "integrations"."id" = "integration_profiles"."integration_id" WHERE "integrations"."provider" = 'kickstarter' (pid:65570)

这工作：

ps = (
  Profile.select(:id)
    .joins(:integrations)
    .where(integrations: { provider: 'csv' })
    .intersect(
      Profile.select(:id)
        .joins(:integrations)
        .where(integrations: {provider: 'kickstarter'})
    )
)
Profile.from(Profile.arel_table.create_table_alias(ps, :profiles))

有办法一步一步完成吗？或者一种让ps输出结果的方法--它只是输出一个Arel对象.

Answer 1

您可以加入2次integration_profiles和像这样的集成：

Profile
  .joins("INNER JOIN integration_profiles AS ip_csv ON ip_csv.profile_id = profiles.id")
  .joins("INNER JOIN integrations AS i_csv ON i_csv.id = ip_csv.integration_id")
  .joins("INNER JOIN integration_profiles AS ip_kickstarter ON ip_kickstarter.profile_id = profiles.id")
  .joins("INNER JOIN integrations AS i_kickstarter ON i_kickstarter.id = ip_kickstarter.integration_id")
  .where("i_csv.provider='csv' AND i_kickstarter.provider='kickstarter'")
  .pluck("profiles.id")

如果您想要一个更具可读性的查询，请定义以下两个作用域：

class Profile < ActiveRecord::Base
  has_many :integration_profiles
  has_many :integrations, through: :integration_profiles

  scope :csv,         ->{joins(:integrations).where(integrations: { provider: 'csv' })}
  scope :kickstarter, ->{joins(:integrations).where(integrations: { provider: 'kickstarter' })}
end

然后：

Profile.csv.where(id: Profile.kickstarter.pluck(:id) ).pluck(:id)

您将得到两个查询，但这读起来要好得多。

SELECT "profiles"."id" FROM "profiles"
INNER JOIN "integration_profiles" ON "integration_profiles"."profile_id" = "profiles"."id" 
INNER JOIN "integrations" ON "integrations"."id" = "integration_profiles"."integration_id" 
WHERE "integrations"."provider" = 'kickstarter'

SELECT "profiles"."id" FROM "profiles"
INNER JOIN "integration_profiles" ON "integration_profiles"."profile_id" = "profiles"."id" 
INNER JOIN "integrations" ON "integrations"."id" = "integration_profiles"."integration_id" 
WHERE "integrations"."provider" = 'csv' AND "profiles"."id" IN (1, 3)

如果只需要配置文件的ids，则可以选择另一条路径:从profile_id中提取integration_profiles：

class Integration < ActiveRecord::Base
  has_many :integration_profiles
  has_many :profiles, through: :integration_profiles

  scope :csv,         -> { where(provider: 'csv') }
  scope :kickstarter, -> { where(provider: 'kickstarter') }
end

class IntegrationProfile < ActiveRecord::Base
  belongs_to :integration
  belongs_to :profile
end

IntegrationProfile.joins(:integration).csv.where(
  profile_id: IntegrationProfile.joins(:integration).kickstarter.pluck(:profile_id)
).pluck(:profile_id)

这仍然会生成2个查询，但这些查询更简单：

SELECT "integration_profiles"."profile_id" FROM "integration_profiles"
INNER JOIN "integrations" ON "integrations"."id" = "integration_profiles"."integration_id" 
WHERE "integrations"."provider" = 'kickstarter'

SELECT "integration_profiles"."profile_id" FROM "integration_profiles"
INNER JOIN "integrations" ON "integrations"."id" = "integration_profiles"."integration_id" 
WHERE "integrations"."provider" = 'csv' AND "integration_profiles"."profile_id" IN (1, 3)