From f63e6e6dabe71ac4f21716f5251189fb28a31430 Mon Sep 17 00:00:00 2001
From: Peter Le Bek <peteralebek@gmail.com>
Date: Tue, 22 Jul 2014 23:47:11 -0400
Subject: [PATCH] Optimize Category find-by-id by using a hash.

---
 app/assets/javascripts/discourse/models/category.js |  9 ++++++---
 app/assets/javascripts/discourse/models/site.js     |  9 +++++----
 test/javascripts/models/category_test.js            | 13 +++++++------
 3 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/app/assets/javascripts/discourse/models/category.js b/app/assets/javascripts/discourse/models/category.js
index 8fa361c64d3..eebb1dbc64c 100644
--- a/app/assets/javascripts/discourse/models/category.js
+++ b/app/assets/javascripts/discourse/models/category.js
@@ -214,15 +214,18 @@ Discourse.Category.reopenClass({
     return Discourse.Site.currentProp('sortedCategories');
   },
 
+  map: function() {
+    return Discourse.Site.currentProp('categoriesById');
+  },
+
   findSingleBySlug: function(slug) {
     return Discourse.Category.list().find(function(c) {
       return Discourse.Category.slugFor(c) === slug;
     });
   },
 
-  // TODO: optimise, slow for no real reason
-  findById: function(id){
-    return Discourse.Category.list().findBy('id', id);
+  findById: function(id) {
+    return Discourse.Category.map()[id];
   },
 
   findByIds: function(ids){
diff --git a/app/assets/javascripts/discourse/models/site.js b/app/assets/javascripts/discourse/models/site.js
index 4ff7907dd77..3b8eba08281 100644
--- a/app/assets/javascripts/discourse/models/site.js
+++ b/app/assets/javascripts/discourse/models/site.js
@@ -84,16 +84,17 @@ Discourse.Site.reopenClass(Discourse.Singleton, {
     var result = this._super.apply(this, arguments);
 
     if (result.categories) {
-      var byId = {};
+      result.categoriesById = {};
       result.categories = _.map(result.categories, function(c) {
-        byId[c.id] = Discourse.Category.create(c);
-        return byId[c.id];
+        result.categoriesById[c.id] = Discourse.Category.create(c);
+        return result.categoriesById[c.id];
       });
 
       // Associate the categories with their parents
       result.categories.forEach(function (c) {
         if (c.get('parent_category_id')) {
-          c.set('parentCategory', byId[c.get('parent_category_id')]);
+          c.set('parentCategory',
+            result.categoriesById[c.get('parent_category_id')]);
         }
       });
     }
diff --git a/test/javascripts/models/category_test.js b/test/javascripts/models/category_test.js
index 19a5dd313e7..d7d64e4b0df 100644
--- a/test/javascripts/models/category_test.js
+++ b/test/javascripts/models/category_test.js
@@ -39,13 +39,14 @@ test('findBySlug', function() {
   blank(Discourse.Category.findBySlug('luke', 'leia'), 'luke is blank with an incorrect parent');
 });
 
-test('findByIds', function(){
-  var categories =  [
-        Discourse.Category.create({id: 1}),
-        Discourse.Category.create({id: 2})];
+test('findByIds', function() {
+  var categories =  {
+    1: Discourse.Category.create({id: 1}),
+    2: Discourse.Category.create({id: 2})
+  };
 
-  this.stub(Discourse.Category, 'list').returns(categories);
-  deepEqual(Discourse.Category.findByIds([1,2,3]), categories);
+  this.stub(Discourse.Category, 'map').returns(categories);
+  deepEqual(Discourse.Category.findByIds([1,2,3]), _.values(categories));
 });
 
 test('postCountStats', function() {