Announcement recommendations

db/migrations/20171003103621_create_recommendations.sql

@@ -0,0 +1,11 @@
+-- +micrate Up
+CREATE TABLE recommendations (
+  id BIGSERIAL PRIMARY KEY,
+  announcement_id INTEGER NOT NULL,
+  recommended_id INTEGER NOT NULL,
+  created_at TIMESTAMP,
+  updated_at TIMESTAMP
+);
+
+-- +micrate Down
+DROP TABLE IF EXISTS recommendations;

public/stylesheets/main.css

@@ -844,6 +844,7 @@ a:focus {
 	position: relative;
 	text-transform: uppercase;
 	z-index: 2;
+	padding: 5% 5% 1%;
 }
 
 .post-navigation .post-title {
@@ -855,6 +856,10 @@ a:focus {
 	z-index: 2;
 }
 
+.nav-links .post-title:not(:last-child) {
+	border-bottom: 1px solid rgba(51, 51, 51, 0.1);
+}
+
 .post-navigation .nav-next,
 .post-navigation .nav-previous {
 	background-position: center;
@@ -4109,7 +4114,7 @@ div.connect-twitter {
 	}
 
 	.post-navigation a {
-		padding: 5% 10%;
+		padding: 4% 10%;
 	}
 
 	.pagination {

shard.lock

@@ -80,6 +80,10 @@ shards:
     github: luislavena/radix
     version: 0.3.8
 
+  recommender:
+    github: hugoabonizio/recommender.cr
+    version: 0.1.0
+
   redis:
     github: stefanwille/crystal-redis
     version: 1.8.0
@@ -90,7 +94,7 @@ shards:
 
   shell-table:
     github: jwaldrip/shell-table.cr
-    version: 0.9.1
+    version: 0.9.2
 
   sidekiq:
     github: mperham/sidekiq.cr
@@ -112,6 +116,10 @@ shards:
     github: crystal-lang/crystal-sqlite3
     version: 0.8.2
 
+  stemmer:
+    github: hugoabonizio/stemmer.cr
+    commit: 1ca4d8c2023c32da006c9ae138f90b327e939016
+
   string_inflection:
     github: mosop/string_inflection
     version: 0.2.1

shard.yml

@@ -43,6 +43,10 @@ dependencies:
     github: crystal-community/autolink.cr
     version: 0.1.3
 
+  recommender:
+    github: hugoabonizio/recommender.cr
+    version: 0.1.0
+
 development_dependencies:
   spec2:
     github: waterlink/spec2.cr

src/controllers/announcement_controller.cr

@@ -14,7 +14,6 @@ class AnnouncementController < ApplicationController
 
   def show
     if announcement = Announcement.find params["id"]
-      newer, older = announcement.next, announcement.prev
       render("show.slang")
     else
       redirect_to "/"

src/models/announcement.cr

@@ -22,6 +22,8 @@ class Announcement < Granite::ORM::Base
   field description : String
   timestamps
 
+  has_many :recommendations
+
   validate :title, "is too short",
     ->(this : Announcement) { this.title.to_s.size >= 5 }
 
@@ -102,6 +104,10 @@ class Announcement < Granite::ORM::Base
     Autolink.auto_link(Markdown.to_html(description.not_nil!))
   end
 
+  def load_recommendations
+    Announcement.all("WHERE id IN(#{recommendations.map(&.recommended_id).join(',')})")
+  end
+
   def self.random
     Announcement.all("ORDER BY RANDOM() LIMIT 1").first?
   end

src/models/recommendation.cr

@@ -0,0 +1,11 @@
+require "granite_orm/adapter/pg"
+
+class Recommendation < Granite::ORM::Base
+  adapter pg
+
+  belongs_to :announcement
+
+  field announcement_id : Int32
+  field recommended_id : Int32
+  timestamps
+end

src/views/announcement/show.slang

@@ -4,14 +4,7 @@
 
 nav.navigation.post-navigation role="navigation"
   div.nav-links
-    - if newer
-      div.nav-next
-        a href="/announcements/#{newer.id}"
-          span.meta-nav Previous
-          span.post-title = newer.title
-
-    - if older
-      div.nav-previous
-        a href="/announcements/#{older.id}"
-          span.meta-nav Next
-          span.post-title = older.title
+    span.meta-nav See more
+    - announcement.load_recommendations.each do |recommended|
+      a.post-title href="/announcements/#{recommended.id}"
+        = recommended.title

src/workers/recommender.cr

@@ -0,0 +1,40 @@
+require "recommender"
+require "sidekiq"
+require "../models/announcement"
+require "../models/recommendation"
+
+module Workers
+  class Recommender
+    include Sidekiq::Worker
+
+    def perform
+      clear_recommendations
+      announcements = Announcement.all
+      preprocessed_announcements = announcements.map { |a| "#{a.title} #{a.description}" }
+      recommender = ::Recommender::ContentBased.new(preprocessed_announcements)
+
+      signal = Channel(Nil).new
+
+      preprocessed_announcements.each_with_index do |_, i|
+        ids = recommender.similar_to(i).first(3)
+        ids.each do |j|
+          data = {
+            :announcement_id => announcements[i].id,
+            :recommended_id  => announcements[j].id,
+          }
+          recommendation = Recommendation.new(data)
+          spawn do
+            recommendation.save
+            signal.send nil
+          end
+        end
+      end
+
+      preprocessed_announcements.size.times { signal.receive }
+    end
+
+    private def clear_recommendations
+      Recommendation.clear
+    end
+  end
+end