rails 5 个 HABTM 协会

Question

如何获得 current_user 的 UserSkill table 中尚不存在的所有技能？

class User < ApplicationRecord
    has_many :user_skills
    has_many :skills, through: :user_skills
end

class Skill < ApplicationRecord
    has_many :user_skills
    has_many :users, through: :user_skills
   end

class UserSkill < ApplicationRecord
    belongs_to :user
    belongs_to :skill
end

我试过这个：

@available_user_skills = Skill.includes(:user_skills).where.not( :user_skills => { :user_id => current_user } )

它只加载技能 table 中存在的所有技能。

Answer 1

我想你正在找这个

user_skill_ids = UserSkill.where(user_id: current_user.id).pluck(:skill_id)
not_user_skills = Skill.where.not(id: user_skill_ids)

或一行

not_user_skills = Skill.where.not(id: current_user.skills.pluck(:id))

这里not_user_skills是不属于current_user

的技能

希望对您有所帮助！

Answer 2

尝试如下：

Skill.includes(:user_skills).where.not(user_skills: {users: {id: current_user.id}})

Answer 3

Skill.joins("LEFT OUTER JOIN user_skills ON skills.id = user_skills.skill_id").where("user_skills.user_id != #{current_user.id}")

希望这对您有所帮助。