From 0f5104d7208b706e9a0353d3d4ccb20683e81bde Mon Sep 17 00:00:00 2001
From: Brian Samson <brian@briansamson.com>
Date: Thu, 24 Nov 2011 13:11:33 -0700
Subject: [PATCH] load has_many associations keyed off a custom primary key if
 that key is present but the record is unsaved

---
 .../associations/collection_association.rb    |  2 +-
 .../associations/has_many_association.rb      |  4 +++
 .../has_many_associations_test.rb             | 29 ++++++++++++++++++-
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/activerecord/lib/active_record/associations/collection_association.rb b/activerecord/lib/active_record/associations/collection_association.rb
index 362f1053cd..af37909c89 100644
--- a/activerecord/lib/active_record/associations/collection_association.rb
+++ b/activerecord/lib/active_record/associations/collection_association.rb
@@ -235,7 +235,7 @@ def destroy(*records)
       # 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
diff --git a/activerecord/lib/active_record/associations/has_many_association.rb b/activerecord/lib/active_record/associations/has_many_association.rb
index 3353cdf1ef..c5b90e873a 100644
--- a/activerecord/lib/active_record/associations/has_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_association.rb
@@ -103,6 +103,10 @@ def delete_records(records, method)
             end
           end
         end
+        
+        def foreign_key_present?
+          owner.attribute_present?(reflection.association_primary_key)
+        end
     end
   end
 end
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index a60af7c046..88d7d47aea 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -8,6 +8,7 @@
 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 @@ def test_should_count_distinct_results
 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
@@ -1390,6 +1391,32 @@ def test_calling_first_or_last_on_new_record_should_not_run_queries
       firm.clients.last
     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)
-- 
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