Recent Activities in Ruby on Rails

Question

What is the best way to implement a StackOverflow-style Recent Activities page?

I have a Gallery with user's photos and I want them to be notified when other users comment or vote their photos.

Should I create a new table which contains recent activities (updated whenever a user posts a comment or votes) or should I simply use a MySQL query?

Answer 1

The short answer is : it depends. If you only need most recent activities and don't need to keep track of activities, or a full 'activity feed' feature, SQL is the way to go. but if you see the need to do a full activity feed kind thing, You can create a model for it.

We did a activity stream recently on our project. Here is how we modeled it

Class Activity
   belongs_to :user_activities # all the people that cares about the activity
   belongs_to :actor, class_name='user' # the actor that cause the activity

   belongs_to :target, :polymorphic => true # the activity target(e.g. if you vote an answer, the target can be the answer )
   belongs_to :subtarget, :polymorphic => true # the  we added this later since we feel the need for a secondary target, e.g if you rate an answer, target is your answer, secondary target is your rating. 

   def self.add(actor, activity_type, target, subtarget = nil)
     activity = Activity.new(:actor => actor, :activity_type => activity_type, :target => target, :subtarget => subtarget)
     activity.save!
     activity
   end 
end

in the answer_controller we do

Class AnswersController
    def create
        ...
        Activity.add(current_user, ActivityType::QUESTION_ANSWERED, @answer)
        ...
    end
end

To get a recent activity list from a user we do

@activities = @user.activities