ruby-on-rails – 在相同的2个模型之间有多个has_many / belongs_to

2019年7月21日 188次阅读

我很好奇这是如何工作的……我在同一个两个模型之间有几个关系.这适用于日历应用,因此可以邀请用户参加活动,用户可以参加活动,并且活动属于用户,以便查看谁创建了活动.

user.rb

class User < ActiveRecord::Base
  has_many :invites, dependent: :destroy
  has_many :events, through: :invites

  has_many :events

  has_many :attendances, -> { where cancel: false },
                         dependent: :destroy                     
  has_many :events, -> { where "attendances.cancel" => false },
                    through: :attendances

event.rb

class Event < ActiveRecord::Base
  has_many :invites, dependent: :destroy
  has_many :users, through: :invites

  belongs_to :user

  has_many :attendances, -> { where cancel: false },
                         dependent: :destroy              
  has_many :users, -> { where "attendances.cancel" => false },
                   through: :attendances

我还有相应的连接表,在各自的模型中控制,attendance.rb和invite.rb.

所以…这可以按预期工作.用户在参加活动时有活动.我做了一些调整,并意识到这是检查列表中的最后一件事.所以,如果我将邀请移到底部,那么当我执行User.find(1).events之类的操作时,就会检查这些内容.

有没有更好的方法来解决这个问题？我觉得这只是在惹麻烦,不是吗？

最佳答案 当我之前完成此操作时,我刚刚将关系的名称更改为更独特的名称,然后告诉has_many通过class_name查看哪个类.您可能还必须在这些已更改的关系上添加foreign_key参数,因此SQL知道要匹配哪个键.

这是基本的想法：

user.rb

class User < ActiveRecord::Base
  has_many :invites, dependent: :destroy
  has_many :invited_events, through: :invites, source: "Event"

  has_many :events # these are events "owned" by the user

  has_many :attendances, -> { where cancel: false }, dependent: :destroy
  has_many :attended_events, -> { where "attendances.cancel" => false }, through: :attendances, source: "Event"
end

event.rb

class Event < ActiveRecord::Base
  has_many :invites, dependent: :destroy
  has_many :invitees, through: :invites, source: "User"

  belongs_to :user # this is the owner of the event

  has_many :attendances, -> { where cancel: false }, dependent: :destroy
  has_many :attendees, -> { where "attendances.cancel" => false }, through: :attendances, source: "User"
end
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