Получение всего сообщения от нескольких предметов

Question

Я хочу показать все сообщение, которое связано только со всеми темами пользователя. Я пробовал и пытался, но я всегда получаю ошибку. Это слишком запутанно, потому что для меня это очень много. Вот модели.

class Post 
    include Mongoid::Document 
    include Mongoid::Timestamps 

    field :content, type: String 
    field :locked , type: Boolean 
    field :unlocked_at , type: Date 

    validates_presence_of :content 

    belongs_to :subject 
    belongs_to :user , inverse_of: :posted_by , class_name: "User" 
    has_many :comments,dependent: :delete 
    has_many :video_attachments , inverse_of: :posts , dependent: :delete 
    accepts_nested_attributes_for :video_attachments, autosave: true 
    accepts_nested_attributes_for :comments, autosave: true 

end 

require "mongoid/token" 
class Subject 
    include Mongoid::Document 
    include Mongoid::Token 

    field :title , type: String 
    field :desc , type: String 

    has_and_belongs_to_many :admins , inverse_of: :admin_of , class_name: "User" 
    has_and_belongs_to_many :students , inverse_of: :student_of , class_name: "User" 
    has_many :posts 
    token length: 6 

end 

class User 
    include Mongoid::Document 
    authenticates_with_sorcery! 
    mount_uploader :avatar , AvatarUploader 

    #fields 
    #field :email , type: String 
    field :id_number , type: String 
    field :crypted_password , type: String 
    field :salt , type: String 
    field :fname , type: String 
    field :lname , type: String 
    field :mname , type: String 
    field :avatar 
    field :gender , type: Boolean 
    field :role , type: String , default: "Student" 


    #relations 
    has_and_belongs_to_many :admin_of , inverse_of: :admins , class_name: "Subject" 
    has_and_belongs_to_many :student_of , inverse_of: :students , class_name: "Subject" 
    has_one :user_detail 
    has_many :posts , inverse_of: :user , class_name: "Post" 
    has_many :comments 
    accepts_nested_attributes_for :user_detail , autosave: true 


end 

Answer 1

current_user = User.find("5492ca884d696c7bbe040000") 
posts = current_user.student_of.collect(&:posts).flatten