Merge commit 'd3ea93c61844b248d60493e0d58e42f2327454c6'

lib/action_controller/parameters.rb

@@ -33,7 +33,7 @@ def permit!
     def require(key)
       self[key].presence || raise(ActionController::ParameterMissing.new(key))
     end
-    
+
     alias :required :require
 
     def permit(*filters)
@@ -97,6 +97,11 @@ def convert_hashes_to_parameters(key, value)
       def each_element(object)
         if object.is_a?(Array)
           object.map { |el| yield el }.compact
+        # fields_for on an array of records uses numeric hash keys
+        elsif object.is_a?(Hash) && object.keys.all? { |k| k =~ /\A\d+\z/ }
+          hash = object.class.new
+          object.each { |k,v| hash[k] = yield v }
+          hash
         else
           yield object
         end

test/nested_parameters_test.rb

@@ -77,4 +77,22 @@ class NestedParametersTest < ActiveSupport::TestCase
     permitted = params.permit :book=> { :genre=> :type }
     assert_nil permitted[:book][:genre]
   end
+
+  test "fields_for_style_nested_params" do
+    params = ActionController::Parameters.new({
+      book: {
+        authors_attributes: {
+          :'0' => { name: 'William Shakespeare', age_of_death: '52' },
+          :'1' => { name: 'Unattributed Assistant' }
+        }
+      }
+    })
+    permitted = params.permit book: { authors_attributes: [ :name ] }
+
+    assert_not_nil permitted[:book][:authors_attributes]['0']
+    assert_not_nil permitted[:book][:authors_attributes]['1']
+    assert_nil permitted[:book][:authors_attributes]['0'][:age_of_death]
+    assert_equal 'William Shakespeare', permitted[:book][:authors_attributes]['0'][:name]
+    assert_equal 'Unattributed Assistant', permitted[:book][:authors_attributes]['1'][:name]
+  end
 end