Select <ActiveRecord::Associations::CollectionProxy> 中的正确记录

Question

我想了解我在这里做错了什么 - 如果有人能给我指出正确的方向，那就太好了！

我的申请中有以下关联：

class Notification < ApplicationRecord
    belongs_to :notificationable, polymorphic: true
end


class AccessPermission < ApplicationRecord
    belongs_to :project
    has_many :notifications, as: :notificationable, dependent: :destroy
end

在我的一个控制器中，我有一个调用可以找到属于一个项目的所有访问权限，然后 select 该访问权限集合的所有通知。但是我有点麻烦。我认为像 AccessPermission.where(project_id: 1).notifications 这样的调用会起作用，但它不起作用。所以我在 ruby 中使用 .map

来做这个


if AccessPermission.where(project_id: 1).map(&:notifications).include?(Notification.where(recipient_id: 1))
            
    #Here is where I need help. Find the notification record in the ActiveRecord::Associations that made the call above "True." I tried:
     notification = AccessPermission.where(project_id: 1).map(&:notifications).find(Notification.where(recipient_id: 1)).first

    ## That did not work, it returns an enumerator and then selects the very first object of the array no matter what the recipient_id is

else
            
    #create the notification if no notification exists
    access_permission.create_notification(recipient_id: 1)
end

Answer 1

你想要一个 has_many 通过项目模型的关系。

类似于：

  has_many :notifications, through: :access_permissions

那你就可以了

  project.notifications

得到你想要的。应该很好地扩展，它会加入查询的表。

完成后，您可以执行以下操作：

project = Project.find(1)

if (notification = project.notifications.find_by(recipient_id: 1))
  # Do something with your notification here
else
  access_permission.create_notification(recipient_id: 1)
end

Select <ActiveRecord::Associations::CollectionProxy> 中的正确记录

Select the correct record in an <ActiveRecord::Associations::CollectionProxy>

sql

activerecord

ruby-on-rails