Leaderboard

Installation

1. Run rails server
2. Connect to http://localhost:3000/leaderboards

Test data

For test, excute the following rake task to insert test score data to redis.

bundle exec rake leaderboard:add_test_data

To delete all leaderboard data from redis

bundle exec rake leaderboard:clear    

Models

Models for leaderboard are Leaderboard, Leaderboad::Score, and Leaderboard::Member. It uses redis as backend datastore. The base namespace of leaderboard is cs:leaderboard.

Leaderboard

Leaderboard#leaders method will return leaders that matche options. Options are community, category, year, month, and page. The default value of each option is "all".

Leaderboard.leaders 
Leaderboard.leaders community: "java"
Leaderboard.leaders community: "java", category: "ruby"
Leaderboard.leaders community: "java", category: "ruby", year: "2012", month: "10"
Leaderboard.leaders category: "ruby", page: 2

Leaderboard::Score

Score model is in charge of constructing leaderboard. When saving score, it updates all concerned leaderboards. Let's say score is in community 'java', and category 'ios', and date is "2012-06". Then it will update the following leaderboards.

'cs:leaderboard:java:all:all:all:prizes'
'cs:leaderboard:java:all:2012:all:prizes'
'cs:leaderboard:java:all:2012:6:prizes'
'cs:leaderboard:java:ios:all:all:prizes'
'cs:leaderboard:java:ios:2012:all:prizes'
'cs:leaderboard:java:ios:2012:6:prizes'

Score data itself is stored in redis to avoid duplication. When the same score(with same username and challenge_id) is requested to save, it will just return false without doing anything.

Leaderboard::Member

Member model is for the view. It has name and picture fields which are stored in redis. total_prizes, rank, and total_wins fields are updated dynamically when getting leaders.(see leaderboard.rb)

Integrating with the real world

When the app receives 'update' event of challenge from database.com(streaming.rb file), it can construct score instances from the challenge_prizes__r attribute. Then, call score.save.
For Instance,

scores = challenge.scores   # Challenge#scores is not yet implemented
scores.each {|s| s.save}

To make the above possible, records of challenge_prizes__r needs member_name of member_id field to identify who the score is belonged to.

For member, when app receives 'create' event of member, it can save leaderboard member. For Instance,

lb_member = Leaderboard::Member.new(name: member.name, picture: member.profile_pic)
lb_member.save

View

The design is almost same as current leaderboard site.

Changes are

• Select box of Community is newly added. If you select one community, it will show leaders of selected community.
• previous and next arrow is added next to the title like 'This Month'. So you can navigate to previous month, or previous year.