有查詢工作，但需要ActiveRelation而不是

A project有legacy_users和group_users。 group_users必須經過groups得到users。我想構建一個project.users，將這些查詢合併爲一個arel。有查詢工作，但需要ActiveRelation而不是

這裏是Project：

class Project < ActiveRecord::Base 
    has_many :project_accesses 

    has_many :groups,  through: :project_accesses, source: :group 
    has_many :legacy_users, through: :project_accesses, source: :user 
    has_many :group_users, through: :groups, source: :users 
end

這裏是Project.find(1).legacy_users SQL：

SELECT "users".* FROM "users" INNER JOIN "project_accesses" ON "users"."id" = 
"project_accesses"."user_id" WHERE "users"."deleted_at" IS NULL AND 
"project_accesses"."deleted_at" IS NULL AND "project_accesses"."project_id" = 1

這裏是Project.find(1).group_users SQL：

SELECT "users".* FROM "users" INNER JOIN "group_memberships" ON "users"."id" = 
"group_memberships"."user_id" INNER JOIN "groups" ON "group_memberships"."group_id" = 
"groups"."id" INNER JOIN "project_accesses" ON "groups"."id" = 
"project_accesses"."group_id" WHERE "users"."deleted_at" IS NULL AND 
"group_memberships"."deleted_at" IS NULL AND "groups"."deleted_at" IS NULL AND 
"project_accesses"."deleted_at" IS NULL AND "project_accesses"."project_id" = 1

通過簡單地在INNER JOIN "project_accesses"賴斯添加OR重刑，我得到了我想要的。 Project.find(1).users：

SELECT "users".* FROM "users" INNER JOIN "group_memberships" ON "users"."id" = 
"group_memberships"."user_id" INNER JOIN "groups" ON "group_memberships"."group_id" = 
"groups"."id" INNER JOIN "project_accesses" ON ("groups"."id" = 
"project_accesses"."group_id" OR "users"."id" = "project_accesses"."user_id") WHERE 
"users"."deleted_at" IS NULL AND "group_memberships"."deleted_at" IS NULL AND 
"groups"."deleted_at" IS NULL AND "project_accesses"."deleted_at" IS NULL AND 
"project_accesses"."project_id" = 1

基本上我只是改變使查詢做我想做的：

INNER JOIN "project_accesses" ON ("groups"."id" = "project_accesses"."group_id" OR "users"."id" = "project_accesses"."user_id")

問題是，現在，這僅僅是傳遞到find_by_sql一個字符串，我想不出如何使這是一個適當的Arel。

在此先感謝您的幫助！

來源

2013-09-26 Dave Bryand

您應該能夠使用ARel的joins方法手動構建您的聯接並仍然獲取活動關係。

http://api.rubyonrails.org/classes/ActiveRecord/QueryMethods.html#method-i-joins

來源

2013-09-27 03:32:17

我越來越近：

User.joins(:groups).joins("inner join project_accesses on (groups.id = 
project_accesses.group_id or users.id = project_accesses.user_id)"). 
where(project_accesses: {project_id:1}).merge(Group.scoped). 
merge(GroupMembership.scoped).merge(ProjectAccess.scoped).uniq

有什麼辦法來寫這個部分阿雷爾？

joins("inner join project_accesses on (groups.id = 
project_accesses.group_id or users.id = project_accesses.user_id)")

此外，有沒有辦法自動包含所有連接模型的默認範圍，以避免：

.merge(Group.scoped).merge(GroupMembership.scoped).merge(ProjectAccess.scoped)

來源

2013-09-27 18:39:34

有查詢工作，但需要ActiveRelation而不是

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