Rails 5.作用域链接的错误结果

Question

我有下一个模型

user.rb

class User < ApplicationRecord
  has_many :user_tags, dependent: :destroy
  has_many :tags, through: :user_tags
  has_many :children, foreign_key: 'parent_id', dependent: :destroy

tag.rb

class Tag < ApplicationRecord
  has_many :user_tags, dependent: :destroy
  has_many :users, through: :user_tags

user_tag.rb

class UserTag < ApplicationRecord
  belongs_to :tag
  belongs_to :user

child.rb

class Child < ApplicationRecord
  belongs_to :parent, class_name: 'User'

在模型用户中，我有几个范围。

选择与所有必需标签相关联的用户:

scope :search_by_tags, -> (ids) {
  joins(:tags).where(tags: {id: ids}).having('COUNT(tags.id) >= ?', ids.count).group('users.id') 
}

生成下一个SQL请求

SELECT "users".* FROM "users" INNER JOIN "user_tags" ON "user_tags"."user_id" = "users"."id" INNER JOIN "tags" ON "tags"."id" = "user_tags"."tag_id" WHERE "tags"."id" IN (17, 37, 70, 8, 11, 3, 91, 64) GROUP BY users.id HAVING (COUNT(tags.id) >= 8)

其他范围选择用户，与特定年龄的儿童相关联

scope :children_in_ages, -> (age_ranges) {
    joins(:children).where(children_ages_query(age_ranges))
      .where.not(children: {gender: -1}).group('users.id')
}
def self.children_ages_query(age_ranges)
    child_table = Child.arel_table
    range_conditions = age_ranges.map { |r| child_table[:birth_date].in(r) }
    range_conditions.inject(range_conditions.shift, &:and).to_sql
end

，其中age_ranges为日期数组。这个作用域生成下一个SQL查询:

SELECT "users".* FROM "users" INNER JOIN "children" ON "children"."parent_id" = "users"."id" WHERE ("children"."birth_date" BETWEEN '2016-02-29 08:35:00.322919' AND '2016-08-31 08:35:00.327283') AND ("children"."gender" != $1) GROUP BY users.id

单独地，作用域工作正确，但当我合并作用域时，我有错误的结果。

User.children_in_ages(a).search_by_tags(ids)
  User Load (85.2ms)  SELECT "users".* FROM "users" INNER JOIN "children" ON "children"."parent_id" = "users"."id" INNER JOIN "user_tags" ON "user_tags"."user_id" = "users"."id" INNER JOIN "tags" ON "tags"."id" = "user_tags"."tag_id" WHERE ("children"."birth_date" BETWEEN '2016-02-29 08:35:00.322919' AND '2016-08-31 08:35:00.327283') AND ("children"."gender" != $1) AND "tags"."id" IN (17, 37, 70, 8, 11, 3, 91, 64) GROUP BY users.id HAVING (COUNT(tags.id) >= 8)

你知道有什么问题吗?

Answer 1

我已经找到解决问题的方法了。

使用特定标签选择用户的正确方法:

模型/user.rb

scope :search_by_tags, -> (ids) { where(id: UserTag.users_with_tags(ids)) unless ids.blank? }

模型/user_tag.rb

scope :users_with_tags, -> (ids) {
  select(:user_id).where(tag: ids).having('COUNT(user_id) >= ?', ids.count).group('user_id')
}

通过这种方式，与其他作用域的链接工作正常