Association#first and last should not load the association if not needed. [#1091 state:resolved]

Signed-off-by: Pratik Naik <pratiknaik@gmail.com>

activerecord/lib/active_record/associations/association_collection.rb

@@ -63,7 +63,7 @@ module ActiveRecord
       
       # Fetches the first one using SQL if possible.
       def first(*args)
-        if fetch_first_or_last_using_find? args
+        if fetch_first_or_last_using_find?(args)
           find(:first, *args)
         else
           load_target unless loaded?
@@ -73,7 +73,7 @@ module ActiveRecord
 
       # Fetches the last one using SQL if possible.
       def last(*args)
-        if fetch_first_or_last_using_find? args
+        if fetch_first_or_last_using_find?(args)
           find(:last, *args)
         else
           load_target unless loaded?
@@ -420,7 +420,8 @@ module ActiveRecord
         end
 
         def fetch_first_or_last_using_find?(args)
-          args.first.kind_of?(Hash) || !(loaded? || @owner.new_record? || @reflection.options[:finder_sql] || !@target.blank? || args.first.kind_of?(Integer))
+          args.first.kind_of?(Hash) || !(loaded? || @owner.new_record? || @reflection.options[:finder_sql] ||
+                                         @target.any? { |record| record.new_record? } || args.first.kind_of?(Integer))
         end
     end
   end

activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb

@@ -253,7 +253,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert !devel.projects.loaded?
 
     assert_equal devel.projects.last, proj
-    assert devel.projects.loaded?
+    assert !devel.projects.loaded?
 
     assert !proj.new_record?
     assert_equal Developer.find(1).projects.sort_by(&:id).last, proj  # prove join table is updated

activerecord/test/cases/associations/has_many_associations_test.rb

@@ -1009,6 +1009,19 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert firm.clients.loaded?
   end
 
+  def test_calling_first_or_last_on_existing_record_with_create_should_not_load_association
+    firm = companies(:first_firm)
+    firm.clients.create(:name => 'Foo')
+    assert !firm.clients.loaded?
+
+    assert_queries 2 do
+      firm.clients.first
+      firm.clients.last
+    end
+
+    assert !firm.clients.loaded?
+  end
+
   def test_calling_first_or_last_on_new_record_should_not_run_queries
     firm = Firm.new