From 25197d72c6a5cad4b047ff0173c3d42fe10da828 Mon Sep 17 00:00:00 2001
From: Andrew France <andrew@avito.co.uk>
Date: Fri, 15 May 2009 01:04:36 +0100
Subject: [PATCH] Allow fields_for_with_nested_attributes to accept collections.

---
 actionpack/lib/action_view/helpers/form_helper.rb |   32 +++++++++++++++---
 actionpack/test/template/form_helper_test.rb      |   36 +++++++++++++++++++++
 2 files changed, 62 insertions(+), 6 deletions(-)

diff --git a/actionpack/lib/action_view/helpers/form_helper.rb b/actionpack/lib/action_view/helpers/form_helper.rb
index beef661..6f05b49 100644
--- a/actionpack/lib/action_view/helpers/form_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_helper.rb
@@ -446,6 +446,16 @@ module ActionView
       #     <% end %>
       #   <% end %>
       #
+      # You can supply a collection to be used:
+      #
+      #   # Note: @active_projects will have been set in the controller.
+      #   <% form_for @person, :url => { :action => "update" } do |person_form| %>
+      #     ...
+      #     <% person_form.fields_for :projects, @active_projects do |project_fields| %>
+      #       Name: <%= project_fields.text_field :name %>
+      #     <% end %>
+      #   <% end %>
+      #
       # When projects is already an association on Person you can use
       # +accepts_nested_attributes_for+ to define the writer method for you:
       #
@@ -1007,18 +1017,28 @@ module ActionView
 
         def fields_for_with_nested_attributes(association_name, args, block)
           name = "#{object_name}[#{association_name}_attributes]"
-          association = @object.send(association_name)
-          explicit_object = args.first if args.first.respond_to?(:new_record?)
 
-          if association.is_a?(Array)
-            children = explicit_object ? [explicit_object] : association
+          obj_arg = args.first
+          if obj_arg.respond_to?(:new_record?)
+            if @object.send(association_name).is_a?(Array)
+              records = [obj_arg]
+            else
+              records = obj_arg
+            end
+          elsif obj_arg.is_a?(Array)
+            records = obj_arg
+          else
+            records = @object.send(association_name)
+          end
+
+          if records.is_a?(Array)
             explicit_child_index = args.last[:child_index] if args.last.is_a?(Hash)
 
-            children.map do |child|
+            records.map do |child|
               fields_for_nested_model("#{name}[#{explicit_child_index || nested_child_index}]", child, args, block)
             end.join
           else
-            fields_for_nested_model(name, explicit_object || association, args, block)
+            fields_for_nested_model(name, records, args, block)
           end
         end
 
diff --git a/actionpack/test/template/form_helper_test.rb b/actionpack/test/template/form_helper_test.rb
index 104649d..0a01f0b 100644
--- a/actionpack/test/template/form_helper_test.rb
+++ b/actionpack/test/template/form_helper_test.rb
@@ -638,6 +638,42 @@ class FormHelperTest < ActionView::TestCase
     assert_dom_equal expected, output_buffer
   end
 
+  def test_nested_fields_for_with_an_empty_supplied_attributes_collection
+    form_for(:post, @post) do |f|
+      concat f.text_field(:title)
+      f.fields_for(:comments, []) do |cf|
+        concat cf.text_field(:name)
+      end
+    end
+
+    expected = '<form action="http://www.example.com" method="post">' +
+               '<input name="post[title]" size="30" type="text" id="post_title" value="Hello World" />' +
+               '</form>'
+
+    assert_dom_equal expected, output_buffer
+  end
+
+  def test_nested_fields_for_with_existing_records_on_a_supplied_nested_attributes_collection
+    @post.comments = Array.new(2) { |id| Comment.new(id + 1) }
+
+    form_for(:post, @post) do |f|
+      concat f.text_field(:title)
+      f.fields_for(:comments, @post.comments) do |cf|
+        concat cf.text_field(:name)
+      end
+    end
+
+    expected = '<form action="http://www.example.com" method="post">' +
+               '<input name="post[title]" size="30" type="text" id="post_title" value="Hello World" />' +
+               '<input id="post_comments_attributes_0_id" name="post[comments_attributes][0][id]" type="hidden" value="1" />' +
+               '<input id="post_comments_attributes_0_name" name="post[comments_attributes][0][name]" size="30" type="text" value="comment #1" />' +
+               '<input id="post_comments_attributes_1_id" name="post[comments_attributes][1][id]" type="hidden" value="2" />' +
+               '<input id="post_comments_attributes_1_name" name="post[comments_attributes][1][name]" size="30" type="text" value="comment #2" />' +
+               '</form>'
+
+    assert_dom_equal expected, output_buffer
+  end
+
   def test_nested_fields_for_with_new_records_on_a_nested_attributes_collection_association
     @post.comments = [Comment.new, Comment.new]
 
-- 
1.6.0.4