LikesTracker

A Rails gem to track likes between two ActiveModel compliant models. A common use case might be that a User likes a Post.

Installation

Add this line to your application’s Gemfile:

gem 'likes_tracker'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install likes_tracker

Dependencies

redis
ruby 1.9+ (it uses some 1.9’s syntax)

Usage

First of all, you need a $redis in your app, you might achieve this using an initializer:

# config/initializers/redis.rb $redis = Redis.new(host: 'localhost', port: '6379', db: '1')

Given you have two models, say User and Post, and you want to track the likes a given Post receives by User(s). Include the LikesTracker module and use the methods it offers to setup models as liker and liked:

``` # app/models/post.rb class Post < ActiveRecord::Base include LikesTracker acts_as_liked_by :users

# rest of the code end

app/models/user.rb

class User < ActiveRecord::Base include LikesTracker acts_as_liker_for :posts

# rest of the code end ```

Now your models will have some methods to manage the likes a model gives to another. Following the above example:

``` > user.likes_post? post => false

user.liked_posts => []

post.likes_users_count => 0

user.like_post! post => [true, true, 1.0]

user.likes_post? post => true ```

As you can see, the methods’ names reflect model names (and they’ll be properly namespaced on Redis). This means, that the same models can like several others, for example User might like another model called Photo or Comment, so you’ll have methods like #like_comment! or #likes_photo? and so on.

How to find Posts liked by a User? There’s a method for this, of course ;-)

> user.liked_posts => [#<Post id: 1, ...>] It returns a relation, such as ActiveRecord::Relation. Even if I haven’t tested it yet, this should work with other ORMs like Mongoid.

``` # a silly example to show how it works > user.liked_posts {|model, ids| p [model, ids] } => [Post(id: integer, …), [“1”]]

the query executed by default

user.liked_posts {|model, ids| model.where(id: ids) } => [#<Post id: 1, …>] ```

Last but not least, here there’re the remaining methods and examples:

``` # you can provide a limit parameter, if omitted it defaults to 5 > Post.most_liked(5) => [#<Post id: 1, …>]

and it also accepts an offset parameter, if omitted it defaults to 0

Post.most_liked(5, 0) => [#<Post id: 1, …>]

last but not least, it accepts a block, like you’ve already seen in above examples

Post.most_liked(5, 0) {|model, ids| p [model, ids] } => [Post(id: integer, …), [“1”]]

post.likes_users_count => 1

user.unlike_post! post => [true, true, 0.0]

user.likes_post? post => false