fix code , refactoring and test

lib/admin_data/active_record_util.rb

@@ -85,6 +85,25 @@ def has_association_info?
       declared_habtm_association_names.any?
     end
 
+    # class User
+    #   has_many :comments
+    # end
+    #
+    # class Car
+    #   has_many :brakes, :foreign_key => 'vehicle_id'
+    # end
+    #
+    # ActiveRecordUtil.foreign_key_for_has_many(User, :comments)
+    # #=> user_id
+    #
+    # ActiveRecordUtil.foreign_key_for_has_many(Car, :brakes)
+    # #=> vehicle_id
+    #
+    def self.foreign_key_for_has_many(klass, relationship_name)
+      fk = klass.reflections[relationship_name].instance_variable_get('@options')[:foreign_key]
+      fk || klass.reflections[relationship_name].instance_variable_get('@active_record').name.foreign_key
+    end
+
     private
 
     # returns declared association names like

lib/admin_data/analytics/hm_association.rb

@@ -13,14 +13,13 @@ def initialize(main_klass, hm_klass, hm_relationship_name)
       end
 
       def count_of_main_klass_records_not_in_hm_klass
-        foreign_key = main_klass.reflections[hm_relationship_name].instance_variable_get('@active_record').name.foreign_key
-        raise 'foreign_key is nil' unless foreign_key
+        foreign_key = AdminData::ActiveRecordUtil.foreign_key_for_has_many(main_klass, hm_relationship_name) 
 
         sql  = %Q{
           
           select count(*) as count_data
           from #{main_klass.table_name}
-          where users.id NOT IN (
+          where #{main_klass.table_name}.id NOT IN (
             select #{hm_klass.table_name}.#{foreign_key}
             from #{hm_klass.table_name}
           )
@@ -31,8 +30,7 @@ def count_of_main_klass_records_not_in_hm_klass
       end
 
       def count_of_main_klass_records_in_hm_klass(count = nil)
-        foreign_key = main_klass.reflections[hm_relationship_name].instance_variable_get('@active_record').name.foreign_key
-        raise 'foreign_key is nil' unless foreign_key
+        foreign_key = AdminData::ActiveRecordUtil.foreign_key_for_has_many(main_klass, hm_relationship_name) 
 
         having_sql = if count
           "having count(#{hm_klass.table_name}.id) = #{count}"

test/rails_root/app/models/brake.rb

@@ -0,0 +1,3 @@
+class Brake < ActiveRecord::Base
+  belongs_to :car
+end

test/rails_root/app/models/car.rb

@@ -1,3 +1,4 @@
 class Car < ActiveRecord::Base
   belongs_to :user
+  has_many :brakes, :foreign_key => 'vehicle_id'
 end

test/rails_root/db/migrate/20091030202259_create_tables.rb

@@ -1,6 +1,12 @@
 class CreateTables < ActiveRecord::Migration
   def self.up
 
+    create_table :brakes do |t|
+      t.string :color
+      t.integer :vehicle_id
+      t.timestamps
+    end
+
     create_table :cars do |t|
       t.string :name
       t.integer :user_id

test/rails_root/test/unit/active_record_util_test.rb

@@ -0,0 +1,17 @@
+require "test_helper"
+require "minitest/autorun"
+
+class ActiveRecordUtilTest < MiniTest::Unit::TestCase
+
+  def test_foreign_key_for_has_many_for_standard_case
+    result = AdminData::ActiveRecordUtil.foreign_key_for_has_many(User, :phone_numbers)
+    assert_equal 'user_id', result
+  end
+
+  def test_foreign_key_for_has_many_for_non_standard_case
+    result = AdminData::ActiveRecordUtil.foreign_key_for_has_many(Car, :brakes)
+    assert_equal 'vehicle_id', result
+  end
+
+end
+