From 2581fe03623d4ee68093aac0300d62f4bd466ebb Mon Sep 17 00:00:00 2001
From: Wasif Hossain <wasifhossain@users.noreply.github.com>
Date: Wed, 17 Jul 2019 15:51:15 +0600
Subject: [PATCH] Lookup fieldset using either string or symbol

---
 active_model_serializers.gemspec        |  2 +-
 lib/active_model/serializer/fieldset.rb |  2 +-
 test/serializers/fieldset_test.rb       | 14 ++++++++++++--
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/active_model_serializers.gemspec b/active_model_serializers.gemspec
index a29ef9dc9..8630cd324 100644
--- a/active_model_serializers.gemspec
+++ b/active_model_serializers.gemspec
@@ -15,7 +15,7 @@ Gem::Specification.new do |spec|
   spec.homepage      = 'https://github.com/rails-api/active_model_serializers'
   spec.license       = 'MIT'
 
-  spec.files         = Dir["CHANGELOG.md", "MIT-LICENSE", "README.md", "lib/**/*"]
+  spec.files         = Dir['CHANGELOG.md', 'MIT-LICENSE', 'README.md', 'lib/**/*']
   spec.require_paths = ['lib']
   spec.executables   = []
 
diff --git a/lib/active_model/serializer/fieldset.rb b/lib/active_model/serializer/fieldset.rb
index 8ed99f899..78609a4e5 100644
--- a/lib/active_model/serializer/fieldset.rb
+++ b/lib/active_model/serializer/fieldset.rb
@@ -12,7 +12,7 @@ def fields
       end
 
       def fields_for(type)
-        fields[type.singularize.to_sym] || fields[type.pluralize.to_sym]
+        fields[type.to_s.singularize.to_sym] || fields[type.to_s.pluralize.to_sym]
       end
 
       protected
diff --git a/test/serializers/fieldset_test.rb b/test/serializers/fieldset_test.rb
index 8237f5d03..781696340 100644
--- a/test/serializers/fieldset_test.rb
+++ b/test/serializers/fieldset_test.rb
@@ -5,11 +5,21 @@
 module ActiveModel
   class Serializer
     class FieldsetTest < ActiveSupport::TestCase
+      def setup
+        @fieldset = ActiveModel::Serializer::Fieldset.new('post' => %w(id title), 'comment' => ['body'])
+      end
+
       def test_fieldset_with_hash
-        fieldset = ActiveModel::Serializer::Fieldset.new('post' => %w(id title), 'comment' => ['body'])
         expected = { post: [:id, :title], comment: [:body] }
 
-        assert_equal(expected, fieldset.fields)
+        assert_equal(expected, @fieldset.fields)
+      end
+
+      def test_fields_for_accepts_string_or_symbol
+        expected = [:id, :title]
+
+        assert_equal(expected, @fieldset.fields_for(:post))
+        assert_equal(expected, @fieldset.fields_for('post'))
       end
     end
   end