refactored error aggregation

app/controllers/errors_controller.rb

@@ -28,7 +28,7 @@ class ErrorsController < ApplicationController
 
   def index
     authorize!
-    @errors = Error.for_execution_environment(@execution_environment)
+    @errors = Error.for_execution_environment(@execution_environment).grouped_by_message
   end
 
   def set_execution_environment

app/models/error.rb

@@ -1,9 +1,8 @@
 class Error < ActiveRecord::Base
   belongs_to :execution_environment
 
-  scope :for_execution_environment, ->(execution_environment) do
-    Error.find_by_sql("SELECT MAX(created_at) AS created_at, MAX(id) AS id, message, COUNT(*) AS count FROM errors WHERE #{sanitize_sql_hash_for_conditions(execution_environment_id: execution_environment.id)} GROUP BY message ORDER BY count DESC")
-  end
+  scope :for_execution_environment, ->(execution_environment) { where(execution_environment_id: execution_environment.id) }
+  scope :grouped_by_message, -> { select('MAX(created_at) AS created_at, MAX(id) AS id, message, COUNT(id) AS count').group(:message).order('count DESC') }
 
   validates :execution_environment_id, presence: true
   validates :message, presence: true

spec/controllers/errors_controller_spec.rb

@@ -67,7 +67,7 @@ describe ErrorsController do
     expect_assigns(execution_environment: :execution_environment)
 
     it 'aggregates errors by message' do
-      expect(assigns(:errors).count).to eq(1)
+      expect(assigns(:errors).length).to eq(1)
     end
 
     expect_status(200)