rails multiple table id find

and use rails polymorphic association..

This is wall_notification.rb

class WallNotification < ActiveRecord::Base
    belongs_to :attachable, polymorphic: true
    belongs_to :user
end

This is picture.rb

class Picture < ActiveRecord::Base
    belongs_to :user
    has_many :wall_notifications, as: :attachable
    mount_uploader :pic_upload
    validates :pic_upload,presence: true
end

This is user_video.rb

class UserVideo < ActiveRecord::Base
    belongs_to :user
    has_many :wall_notifications, as: :attachable
    mount_uploader :user_video
end

This is career.rb

class Career < ActiveRecord::Base
    has_many :wall_notifications, as: :attachable
    mount_uploader :career_file
end

and,when create new picture,user_video,career, wall_notifiacatin will create new record automatically because,we use polymorphic association..

when i check my rails console..polymorphic association perfectly working..

[1] pry(main)> WallNotification.all
  WallNotification Load (220.3ms)  SELECT `wall_notifications`.* FROM `wall_notifications`
=> [#<WallNotification:0xb4b51d0
  id: 1,
  user_id: 1,
  attachable_id: 1,
  attachable_type: "Picture",
  created_at: Wed, 19 Oct 2016 04:50:55 UTC +00:00,
  updated_at: Wed, 19 Oct 2016 04:50:55 UTC +00:00>,
 #<WallNotification:0xb4a98e4
  id: 2,
  user_id: 1,
  attachable_id: 1,
  attachable_type: "UserVideo",
  created_at: Wed, 19 Oct 2016 04:53:43 UTC +00:00,
  updated_at: Wed, 19 Oct 2016 04:53:43 UTC +00:00>,
 #<WallNotification:0xb4a9740
  id: 3,
  user_id: 1,
  attachable_id: 1,
  attachable_type: "Career",
  created_at: Wed, 19 Oct 2016 05:12:43 UTC +00:00,
  updated_at: Wed, 19 Oct 2016 05:12:43 UTC +00:00>]

but now i want to current_user's wall_notifications list..and this is my controller.rb

def index
    @wall_notifications_picture = current_user.wall_notifications.where(attachable_type: 'Picture')
    @picture_ids = @wall_notifications_picture.map {|w| Picture.find_by_id(w.attachable_id)}
    @wall_notifications_uservideo = current_user.wall_notifications.where(attachable_type: 'UserVideo')
    @uservideo_ids = @wall_notifications_uservideo.map {|w| UserVideo.find_by_id(w.attachable_id)}
    @wall_notifications_career = current_user.wall_notifications.where(attachable_type: 'Career')
    @career_ids = @wall_notifications_uservideo.map {|w| Career.find_by_id(w.attachable_id)}
   end

i want each table data in one instance variable :( :( Any one help me..