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 1.8.7 or 1.9.x
- Rails 2.3.x, 3.0.x, 3.1.x (tested with SQLite and MySQL)
- Needs a timestamp field in your models (e.g. created_at) with a database index on it
Step 1: Add this to your Gemfile:
Step 2: Add this migration:
class CreateReadMarks < ActiveRecord::Migration def self.up create_table :read_marks, :force => true do |t| t.integer :readable_id t.integer :user_id, :null => false t.string :readable_type, :null => false, :limit => 20 t.datetime :timestamp end add_index :read_marks, [:user_id, :readable_type, :readable_id] end def self.down drop_table :read_marks end end
and run the migration:
class User < ActiveRecord::Base acts_as_reader end class Message < ActiveRecord::Base acts_as_readable :on => :created_at end = Message.create! = Message.create! Message.unread_by(current_user) # => [ message1, message2 ] .mark_as_read! :for => current_user Message.unread_by(current_user) # => [ message2 ] 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) 2010,2011 Georg Ledermann, released under the MIT license