Fix honoring :primary_key option when joining or eager loading a belongs_to association

[#765 state:committed]
Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>

activerecord/lib/active_record/association_preload.rb

@@ -324,7 +324,7 @@ def preload_belongs_to_association(records, reflection, preload_options={})
           klass = klass_name.constantize
 
           table_name = klass.quoted_table_name
-          primary_key = klass.primary_key
+          primary_key = reflection.options[:primary_key] || klass.primary_key
           column_type = klass.columns.detect{|c| c.name == primary_key}.type
 
           ids = id_map.keys.map do |id|

activerecord/lib/active_record/associations.rb

@@ -2031,7 +2031,7 @@ def association_join
                   [aliased_table[foreign_key].eq(parent_table[reflection.options[:primary_key] || parent.primary_key])]
                 end
               when :belongs_to
-                [aliased_table[reflection.klass.primary_key].eq(parent_table[options[:foreign_key] || reflection.primary_key_name])]
+                [aliased_table[options[:primary_key] || reflection.klass.primary_key].eq(parent_table[options[:foreign_key] || reflection.primary_key_name])]
               end
 
               unless klass.descends_from_active_record?

activerecord/test/cases/associations/belongs_to_associations_test.rb

@@ -32,6 +32,12 @@ def test_belongs_to_with_primary_key
     assert_equal companies(:first_firm).name, client.firm_with_primary_key.name
   end
 
+  def test_belongs_to_with_primary_key_joins_on_correct_column
+    sql = Client.joins(:firm_with_primary_key).to_sql
+    assert_no_match /"firm_with_primary_keys_companies"\."id"/, sql
+    assert_match /"firm_with_primary_keys_companies"\."name"/, sql
+  end
+
   def test_proxy_assignment
     account = Account.find(1)
     assert_nothing_raised { account.firm = account.firm }
@@ -61,6 +67,13 @@ def test_natural_assignment_with_primary_key
     assert_equal apple.name, citibank.firm_name
   end
 
+  def test_eager_loading_with_primary_key
+    apple = Firm.create("name" => "Apple")
+    citibank = Client.create("name" => "Citibank", :firm_name => "Apple")
+    citibank_result = Client.find(:first, :conditions => {:name => "Citibank"}, :include => :firm_with_primary_key)
+    assert_not_nil citibank_result.instance_variable_get("@firm_with_primary_key")
+  end
+
   def test_no_unexpected_aliasing
     first_firm = companies(:first_firm)
     another_firm = companies(:another_firm)