Question

我正在使用jRuby 1.7.16.1

在Rails 4.2.1中编写应用程序

我有用户和项目模型。项目通过加入模型有一个领导者和许多用户：

class Project < ActiveRecord::Base
  has_many :users_projects_join
  has_many :users, :through => :users_projects_join
  has_many :active_users, 
     -> { where(users_projects_join: {user_status: true}) }, 
     :through => :users_projects_join, 
     :source => :user

  belongs_to :leader, :class_name => 'User', :foreign_key => :leader_id
end

我想拥有：active_users所以我写了上面显示的查询，但它给了我

ERROR: missing FROM-clause entry for table "users_projects_join"
  Position: 167: SELECT "users".* FROM "users" 
    INNER JOIN "users_projects_joins" 
    ON "users"."id" = "users_projects_joins"."user_id" 
    WHERE "users_projects_joins"."project_id" = 20 
    AND "users_projects_join"."user_status" = 't'

但是当我在Postgres中严格执行这个查询时，它给了我所有用户user_status为true。我读到我需要添加连接（：users_projects_join）.where（...）但它没有帮助。

Answer 1

立即尝试：

class Project < ActiveRecord::Base
  has_many :users_projects_joins
  has_many :users, :through => :users_projects_joins
  has_many :active_users, 
     -> { where(users_projects_joins: {user_status: true}) }, 
     :through => :users_projects_joins, 
     :source => :user

  belongs_to :leader, :class_name => 'User', :foreign_key => :leader_id
end

为什么我收到表错误的错误FROM子句条目？

1 个答案: