Merge pull request #3748 from samsonasu/has_many_custom_pk_new_record

New records should load has_many relationships with custom primary keys

activerecord/lib/active_record/associations/collection_association.rb

@@ -235,7 +235,7 @@ module ActiveRecord
       # This method is abstract in the sense that it relies on
       # +count_records+, which is a method descendants have to provide.
       def size
-        if owner.new_record? || (loaded? && !options[:uniq])
+        if !find_target? || (loaded? && !options[:uniq])
           target.size
         elsif !loaded? && options[:group]
           load_target.size

activerecord/lib/active_record/associations/has_many_association.rb

@@ -103,6 +103,10 @@ module ActiveRecord
             end
           end
         end
+        
+        def foreign_key_present?
+          owner.attribute_present?(reflection.association_primary_key)
+        end
     end
   end
 end

activerecord/test/cases/associations/has_many_associations_test.rb

@@ -8,6 +8,7 @@ require 'models/reply'
 require 'models/category'
 require 'models/post'
 require 'models/author'
+require 'models/essay'
 require 'models/comment'
 require 'models/person'
 require 'models/reader'
@@ -61,7 +62,7 @@ end
 class HasManyAssociationsTest < ActiveRecord::TestCase
   fixtures :accounts, :categories, :companies, :developers, :projects,
            :developers_projects, :topics, :authors, :comments,
-           :people, :posts, :readers, :taggings, :cars
+           :people, :posts, :readers, :taggings, :cars, :essays
 
   def setup
     Client.destroyed_client_ids.clear
@@ -1391,6 +1392,32 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     end
   end
   
+  def test_custom_primary_key_on_new_record_should_fetch_with_query
+    author = Author.new(:name => "David")
+    assert !author.essays.loaded?
+    
+    assert_queries 1 do 
+      assert_equal 1, author.essays.size
+    end
+    
+    assert_equal author.essays, Essay.find_all_by_writer_id("David")
+    
+  end
+  
+  def test_has_many_custom_primary_key
+    david = authors(:david)
+    assert_equal david.essays, Essay.find_all_by_writer_id("David")
+  end
+  
+  def test_blank_custom_primary_key_on_new_record_should_not_run_queries
+    author = Author.new
+    assert !author.essays.loaded?
+    
+    assert_queries 0 do 
+      assert_equal 0, author.essays.size
+    end
+  end
+
   def test_calling_first_or_last_with_find_options_on_loaded_association_should_fetch_with_query
     firm = companies(:first_firm)
     firm.clients.class # force load target