speed up account pages a bit

 * avoid joining with users just to get the count of associated_users

Change-Id: I79635e7bd189d361fb9f1deee73806ffc40d40db
Reviewed-on: https://gerrit.instructure.com/5321
Tested-by: Hudson <hudson@instructure.com>
Reviewed-by: Zach Wily <zach@instructure.com>

Author: ccutrer

app/models/account.rb

@@ -85,6 +85,7 @@ def inherited_assessment_question_banks(include_self = false, *additional_contex
   has_many :account_notifications
   has_many :alerts, :as => :context, :include => :criteria
   has_many :associated_alerts, :through => :associated_courses, :source => :alerts, :include => :criteria
+  has_many :user_account_associations
 
   before_validation :verify_unique_sis_source_id
   before_save :ensure_defaults
@@ -783,7 +784,12 @@ def sub_account_count
     self.sub_accounts.active.count
   end
   memoize :sub_account_count
-  
+
+  def user_count
+    self.user_account_associations.count
+  end
+  memoize :user_count
+
   def current_sis_batch
     if (current_sis_batch_id = self.read_attribute(:current_sis_batch_id)) && current_sis_batch_id.present?
       self.sis_batches.find_by_id(current_sis_batch_id)

app/views/shared/_accounts_right_side_shared.html.erb

@@ -18,7 +18,7 @@
           serviceUrl: $("#new_user")[0].action + ".json",
           onSelect: function(value, data){
             window.location = $("#new_user")[0].action + "/" + data
-          <% if @account.all_users.count < 500 %>
+          <% if @account.user_count < 500 %>
           },
           lookup: <%= raw({
             :suggestions =>  @account.fast_all_users.map{ |u| u.last_name_first || ""},

app/views/shared/_accounts_secondary_content.html.erb

@@ -29,7 +29,7 @@
           serviceUrl: $newUserForm[0].action + ".json",
           onSelect: function(value, data){
             window.location = data
-          <% if @account.all_users.count < 250 %>
+          <% if @account.user_count < 250 %>
           },
 
           lookup: <%= raw({

spec/models/account_spec.rb

@@ -443,4 +443,31 @@ def account_with_admin_and_restricted_user(account)
         ["    sub2-1", sub2_1.id]
       ]
   end
+
+  it "should return the correct user count" do
+    a = Account.default
+    a.all_users.count.should == a.user_count
+    a.user_count.should == 0
+
+    u = User.create!
+    a.add_user(u)
+    a.all_users.count.should == a.user_count(:reload)
+    a.user_count.should == 1
+
+    course_with_teacher
+    @teacher.update_account_associations
+    a.all_users.count.should == a.user_count(:reload)
+    a.user_count.should == 2
+
+    a2 = a.sub_accounts.create!
+    course_with_teacher(:account => a2)
+    @teacher.update_account_associations
+    a.all_users.count.should == a.user_count(:reload)
+    a.user_count.should == 3
+
+    user_with_pseudonym
+    a.all_users.count.should == a.user_count(:reload)
+    a.user_count.should == 4
+
+  end
 end