Ruby gem to manage read/unread status of ActiveRecord objects - and it's fast.
- Manages unread records for anything you want users to read (like messages, documents, comments etc.)
- Supports mark as read to mark a single record as read
- Supports mark all as read to mark all records as read in a single step
- Gives you a scope to get the unread records for a given user
- Needs only one additional database table
- Most important: Great performance
- Ruby 1.9.3 or newer
- Rails 3 (including 3.0, 3.1, 3.2) and Rails 4. For use with Rails 2.3 there is a branch named "rails2"
- Needs a timestamp field in your models (like created_at or updated_at) with a database index on it
Step 1: Add this to your Gemfile:
Step 2: Generate and run the migration:
rails g unread:migration rake db:migrate
class User < ActiveRecord::Base acts_as_reader end class Message < ActiveRecord::Base acts_as_readable :on => :created_at end = Message.create! = Message.create! ## Get unread messages for a given user Message.unread_by(current_user) # => [ message1, message2 ] .mark_as_read! :for => current_user Message.unread_by(current_user) # => [ message2 ] ## Get all messages including the read status for a given user = Message.with_read_marks_for(current_user) # => [ message1, message2 ] .unread?(current_user) # => false .unread?(current_user) # => true Message.mark_as_read! :all, :for => current_user Message.unread_by(current_user) # => [ ] # Optional: Cleaning up unneeded markers. # Do this in a cron job once a day. Message.cleanup_read_marks!
How does it work?
The main idea of this gem is to manage a list of read items for every reader after a certain timestamp.
The gem defines a scope doing a LEFT JOIN to this list, so your app can get the unread items in a performant manner. Of course, other scopes can be combined.
It will be ensured that the list of read items will not grow up too much:
- If a user uses "mark all as read", his list gets deleted and the timestamp is set to the current time.
- If a user never uses "mark all as read", the list will grow and grow with each item he reads. But there is help: Your app can use a cleanup method which removes unnecessary list items.
Overall, this gem can be used for large data. Please have a look at the generated SQL queries, here is an example:
# Assuming we have a user who has marked all messages as read on 2010-10-20 08:50 current_user = User.find(42) # Get the unread messages for this user Message.unread_by(current_user)
SELECT messages.* FROM messages LEFT JOIN read_marks ON read_marks.readable_type = 'Message' AND read_marks.readable_id = messages.id AND read_marks.user_id = 42 AND read_marks.timestamp >= messages.created_at WHERE read_marks.id IS NULL AND messages.created_at > '2010-10-20 08:50:00'
Hint: You should add a database index on
There are two other gems/plugins doing a similar job:
Unfortunately, both of them have a lack of performance, because they calculate the unread records doing a
find(:all), which should be avoided for a large amount of records. This gem is based on a timestamp algorithm and therefore it's very fast.
Copyright (c) 2010-2014 Georg Ledermann, released under the MIT license