From 39bee48ae63c78cd11b72ec9d1543d6c9c3dd22f Mon Sep 17 00:00:00 2001
From: Aaron Renoir <aaron@fieldphone.com>
Date: Sun, 26 Oct 2014 13:04:14 -0700
Subject: [PATCH 1/4] implement sparse fieldsets
 http://jsonapi.org/format/#fetching-sparse-fieldsets

---
 lib/active_model/serializer.rb                |  9 ++-
 lib/active_model/serializer/adapter.rb        |  1 +
 .../serializer/adapter/json_api.rb            | 10 +++-
 lib/active_model/serializer/fieldset.rb       | 33 +++++++++++
 lib/active_model_serializers.rb               |  1 +
 test/adapter/json_api/fieldset_test.rb        | 56 +++++++++++++++++++
 test/serializers/attributes_test.rb           |  6 +-
 7 files changed, 113 insertions(+), 3 deletions(-)
 create mode 100644 lib/active_model/serializer/fieldset.rb
 create mode 100644 test/adapter/json_api/fieldset_test.rb

diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index 7050dc38..0f1fc2eb 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -124,7 +124,14 @@ module ActiveModel
     end
 
     def attributes(options = {})
-      self.class._attributes.dup.each_with_object({}) do |name, hash|
+      attributes =
+        if options[:fields]
+          self.class._attributes & options[:fields]
+        else
+          self.class._attributes.dup
+        end
+
+      attributes.each_with_object({}) do |name, hash|
         hash[name] = send(name)
       end
     end
diff --git a/lib/active_model/serializer/adapter.rb b/lib/active_model/serializer/adapter.rb
index f0a82573..b8a8b9df 100644
--- a/lib/active_model/serializer/adapter.rb
+++ b/lib/active_model/serializer/adapter.rb
@@ -17,6 +17,7 @@ module ActiveModel
       end
 
       def to_json(options = {})
+        options[:fieldset] = ActiveModel::Serializer::Fieldset.new(serializer, options[:fields])
         serializable_hash(options).to_json
       end
     end
diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index 71327b3c..8f09b82b 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -10,9 +10,12 @@ module ActiveModel
         def serializable_hash(options = {})
           @root = (options[:root] || serializer.json_key).to_s.pluralize.to_sym
           @hash = {}
+          @fieldset = options[:fieldset]
 
           if serializer.respond_to?(:each)
-            @hash[@root] = serializer.map{|s| self.class.new(s).serializable_hash[@root] }
+            opt = @fieldset ? {fieldset: @fieldset} : {}
+        
+            @hash[@root] = serializer.map{|s| self.class.new(s).serializable_hash(opt)[@root] }
           else
             @hash[@root] = attributes_for_serializer(serializer, {})
 
@@ -57,6 +60,11 @@ module ActiveModel
         private
 
         def attributes_for_serializer(serializer, options)
+
+          if fields = @fieldset && @fieldset.fields_for(serializer)
+            options[:fields] = fields
+          end
+
           attributes = serializer.attributes(options)
           attributes[:id] = attributes[:id].to_s if attributes[:id]
           attributes
diff --git a/lib/active_model/serializer/fieldset.rb b/lib/active_model/serializer/fieldset.rb
new file mode 100644
index 00000000..e7d288f7
--- /dev/null
+++ b/lib/active_model/serializer/fieldset.rb
@@ -0,0 +1,33 @@
+module ActiveModel
+  class Serializer
+    class Fieldset
+
+      attr_accessor :fields, :root
+
+      def initialize(serializer, fields = {})
+        @root   = serializer.json_key
+        @fields = parse(fields)
+      end
+
+      def fields_for(serializer)
+        key = serializer.json_key || serializer.class.root_name
+        fields[key]
+      end
+
+    private
+
+      def parse(fields)
+        if fields.is_a?(Hash)
+          fields.inject({}) { |h,(k,v)| h[k.to_s] = v.map(&:to_sym); h}
+        elsif fields.is_a?(Array)
+          hash = {}
+          hash[root.to_s] = fields.map(&:to_sym)
+          hash
+        else
+          {}
+        end
+      end
+
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/active_model_serializers.rb b/lib/active_model_serializers.rb
index c96b90a9..5b0ed1b1 100644
--- a/lib/active_model_serializers.rb
+++ b/lib/active_model_serializers.rb
@@ -1,6 +1,7 @@
 require "active_model"
 require "active_model/serializer/version"
 require "active_model/serializer"
+require "active_model/serializer/fieldset"
 
 begin
   require 'action_controller'
diff --git a/test/adapter/json_api/fieldset_test.rb b/test/adapter/json_api/fieldset_test.rb
new file mode 100644
index 00000000..03619724
--- /dev/null
+++ b/test/adapter/json_api/fieldset_test.rb
@@ -0,0 +1,56 @@
+require 'test_helper'
+
+module ActiveModel
+  class Serializer
+    class Adapter
+      class JsonApi
+        class FieldsetTest < Minitest::Test
+          def setup
+            @post = Post.new(title: 'New Post', body: 'Body')
+            @first_comment = Comment.new(id: 1, body: 'ZOMG A COMMENT')
+            @second_comment = Comment.new(id: 2, body: 'ZOMG ANOTHER COMMENT')
+            @post.comments = [@first_comment, @second_comment]
+            @first_comment.post = @post
+            @second_comment.post = @post
+
+            @serializer = PostSerializer.new(@post)
+            @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer)
+          end
+
+          def teardown
+            @serializer = nil
+            @adapter = nil
+          end
+
+          def test_fieldset_with_fields_array
+            fieldset = ActiveModel::Serializer::Fieldset.new(@serializer, ['title'])
+
+            assert_equal(
+              {:title=>"New Post", :links=>{:comments=>["1", "2"]}}, 
+              @adapter.serializable_hash({fieldset: fieldset})[:posts]
+            )
+          end
+
+          def test_fieldset_with_hash
+            fieldset = ActiveModel::Serializer::Fieldset.new(@serializer, {post: [:body]})
+
+            assert_equal(
+              {:body=>"Body", :links=>{:comments=>["1", "2"]}}, 
+              @adapter.serializable_hash({fieldset: fieldset})[:posts]
+            )
+          end
+
+          def test_fieldset_with_multiple_hashes
+            fieldset = ActiveModel::Serializer::Fieldset.new(@serializer, {post: [:title], comment: [:body]})
+
+            assert_equal(
+              [{:body=>"ZOMG A COMMENT" }, {:body=>"ZOMG ANOTHER COMMENT"}],
+              @adapter.serializable_hash({fieldset: fieldset})[:linked][:comments]
+            )
+          end
+
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/test/serializers/attributes_test.rb b/test/serializers/attributes_test.rb
index f9467b18..7c4bbc8b 100644
--- a/test/serializers/attributes_test.rb
+++ b/test/serializers/attributes_test.rb
@@ -12,7 +12,11 @@ module ActiveModel
         assert_equal([:name, :description],
                      @profile_serializer.class._attributes)
       end
+
+      def test_attributes_with_fields_option
+        assert_equal({name: 'Name 1'},
+                     @profile_serializer.attributes( { fields: [:name] } ) )
+      end
     end
   end
 end
-

From 34f08477e4cc6838668a5a87fe3f61460bac5164 Mon Sep 17 00:00:00 2001
From: Aaron Renoir <aaron@fieldphone.com>
Date: Sun, 26 Oct 2014 14:41:14 -0700
Subject: [PATCH 2/4] fix tests, but need to understand how the serializer
 class attribute _associations was getting changed.

---
 test/adapter/json_api/fieldset_test.rb | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/test/adapter/json_api/fieldset_test.rb b/test/adapter/json_api/fieldset_test.rb
index 03619724..ded4e4a9 100644
--- a/test/adapter/json_api/fieldset_test.rb
+++ b/test/adapter/json_api/fieldset_test.rb
@@ -7,19 +7,13 @@ module ActiveModel
         class FieldsetTest < Minitest::Test
           def setup
             @post = Post.new(title: 'New Post', body: 'Body')
-            @first_comment = Comment.new(id: 1, body: 'ZOMG A COMMENT')
-            @second_comment = Comment.new(id: 2, body: 'ZOMG ANOTHER COMMENT')
-            @post.comments = [@first_comment, @second_comment]
-            @first_comment.post = @post
-            @second_comment.post = @post
+            comment_1 = Comment.new(id: 1, body: 'comment one')
+            comment_2 = Comment.new(id: 2, body: 'comment two')
+            @post.comments = [comment_1, comment_2]
 
             @serializer = PostSerializer.new(@post)
             @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer)
-          end
 
-          def teardown
-            @serializer = nil
-            @adapter = nil
           end
 
           def test_fieldset_with_fields_array
@@ -44,9 +38,13 @@ module ActiveModel
             fieldset = ActiveModel::Serializer::Fieldset.new(@serializer, {post: [:title], comment: [:body]})
 
             assert_equal(
-              [{:body=>"ZOMG A COMMENT" }, {:body=>"ZOMG ANOTHER COMMENT"}],
+              [{:body=>"comment one" }, {:body=>"comment two"}],
               @adapter.serializable_hash({fieldset: fieldset})[:linked][:comments]
             )
+
+            #don't understand how this is getting set.
+            @serializer.class._associations[:comments][:options] = {}
+
           end
 
         end

From be54e0bc4fa6eb0be130ee146614701a0e709e7d Mon Sep 17 00:00:00 2001
From: Aaron Renoir <aaron@fieldphone.com>
Date: Mon, 27 Oct 2014 15:24:19 -0700
Subject: [PATCH 3/4] remove serializer dependency from fieldset

---
 lib/active_model/serializer/adapter.rb  |  5 ++++-
 lib/active_model/serializer/fieldset.rb | 15 ++++++++------
 test/adapter/json_api/fieldset_test.rb  |  6 +++---
 test/serializers/fieldset_test.rb       | 26 +++++++++++++++++++++++++
 4 files changed, 42 insertions(+), 10 deletions(-)
 create mode 100644 test/serializers/fieldset_test.rb

diff --git a/lib/active_model/serializer/adapter.rb b/lib/active_model/serializer/adapter.rb
index b8a8b9df..de46f12a 100644
--- a/lib/active_model/serializer/adapter.rb
+++ b/lib/active_model/serializer/adapter.rb
@@ -17,7 +17,10 @@ module ActiveModel
       end
 
       def to_json(options = {})
-        options[:fieldset] = ActiveModel::Serializer::Fieldset.new(serializer, options[:fields])
+        if fields = options.delete(:fields)
+          options[:fieldset] = ActiveModel::Serializer::Fieldset.new(fields, serializer.json_key)
+        end
+
         serializable_hash(options).to_json
       end
     end
diff --git a/lib/active_model/serializer/fieldset.rb b/lib/active_model/serializer/fieldset.rb
index e7d288f7..dc3ab857 100644
--- a/lib/active_model/serializer/fieldset.rb
+++ b/lib/active_model/serializer/fieldset.rb
@@ -2,26 +2,29 @@ module ActiveModel
   class Serializer
     class Fieldset
 
-      attr_accessor :fields, :root
+      attr_reader :fields, :root
 
-      def initialize(serializer, fields = {})
-        @root   = serializer.json_key
+      def initialize(fields, root = nil)
+        @root   = root
         @fields = parse(fields)
       end
 
       def fields_for(serializer)
         key = serializer.json_key || serializer.class.root_name
-        fields[key]
+        fields[key.to_sym]
       end
 
     private
 
       def parse(fields)
         if fields.is_a?(Hash)
-          fields.inject({}) { |h,(k,v)| h[k.to_s] = v.map(&:to_sym); h}
+          fields.inject({}) { |h,(k,v)| h[k.to_sym] = v.map(&:to_sym); h}
         elsif fields.is_a?(Array)
+          if root.nil?
+            raise ArgumentError, 'The root argument must be specified if the fileds argument is an array.'
+          end
           hash = {}
-          hash[root.to_s] = fields.map(&:to_sym)
+          hash[root.to_sym] = fields.map(&:to_sym)
           hash
         else
           {}
diff --git a/test/adapter/json_api/fieldset_test.rb b/test/adapter/json_api/fieldset_test.rb
index ded4e4a9..cc08ba11 100644
--- a/test/adapter/json_api/fieldset_test.rb
+++ b/test/adapter/json_api/fieldset_test.rb
@@ -17,7 +17,7 @@ module ActiveModel
           end
 
           def test_fieldset_with_fields_array
-            fieldset = ActiveModel::Serializer::Fieldset.new(@serializer, ['title'])
+            fieldset = ActiveModel::Serializer::Fieldset.new(['title'], 'post')
 
             assert_equal(
               {:title=>"New Post", :links=>{:comments=>["1", "2"]}}, 
@@ -26,7 +26,7 @@ module ActiveModel
           end
 
           def test_fieldset_with_hash
-            fieldset = ActiveModel::Serializer::Fieldset.new(@serializer, {post: [:body]})
+            fieldset = ActiveModel::Serializer::Fieldset.new({post: [:body]})
 
             assert_equal(
               {:body=>"Body", :links=>{:comments=>["1", "2"]}}, 
@@ -35,7 +35,7 @@ module ActiveModel
           end
 
           def test_fieldset_with_multiple_hashes
-            fieldset = ActiveModel::Serializer::Fieldset.new(@serializer, {post: [:title], comment: [:body]})
+            fieldset = ActiveModel::Serializer::Fieldset.new({post: [:title], comment: [:body]})
 
             assert_equal(
               [{:body=>"comment one" }, {:body=>"comment two"}],
diff --git a/test/serializers/fieldset_test.rb b/test/serializers/fieldset_test.rb
new file mode 100644
index 00000000..05439177
--- /dev/null
+++ b/test/serializers/fieldset_test.rb
@@ -0,0 +1,26 @@
+require 'test_helper'
+
+module ActiveModel
+  class Serializer
+    class FieldsetTest < Minitest::Test
+
+      def test_fieldset_with_hash
+        fieldset = ActiveModel::Serializer::Fieldset.new({'post' => ['id', 'title'], 'coment' => ['body']})
+
+        assert_equal(
+          {:post=>[:id, :title], :coment=>[:body]}, 
+          fieldset.fields
+        )
+      end
+
+      def test_fieldset_with_array_of_fields_and_root_name
+        fieldset = ActiveModel::Serializer::Fieldset.new(['title'], 'post')
+
+        assert_equal(
+          {:post => [:title]}, 
+          fieldset.fields
+        )
+      end
+    end
+  end
+end
\ No newline at end of file

From fc1562c04ad5df16a264c2a5b7b15f507d5588f7 Mon Sep 17 00:00:00 2001
From: Aaron Renoir <aaron@fieldphone.com>
Date: Wed, 5 Nov 2014 18:10:37 -0800
Subject: [PATCH 4/4] add fields to adapter initialize function, pull in
 master, add tests using includes with fields

---
 lib/action_controller/serialization.rb        |  2 +-
 lib/active_model/serializer/adapter.rb        |  6 +--
 .../serializer/adapter/json_api.rb            | 10 ++--
 test/adapter/json_api/belongs_to_test.rb      |  5 ++
 test/adapter/json_api/collection_test.rb      |  9 ++++
 test/adapter/json_api/fieldset_test.rb        | 54 -------------------
 test/adapter/json_api/has_many_test.rb        |  8 +++
 7 files changed, 31 insertions(+), 63 deletions(-)
 delete mode 100644 test/adapter/json_api/fieldset_test.rb

diff --git a/lib/action_controller/serialization.rb b/lib/action_controller/serialization.rb
index 2b460cb4..aa872ae9 100644
--- a/lib/action_controller/serialization.rb
+++ b/lib/action_controller/serialization.rb
@@ -6,7 +6,7 @@ module ActionController
 
     include ActionController::Renderers
 
-    ADAPTER_OPTION_KEYS = [:include, :root]
+    ADAPTER_OPTION_KEYS = [:include, :fields, :root]
 
     [:_render_option_json, :_render_with_renderer_json].each do |renderer_method|
       define_method renderer_method do |resource, options|
diff --git a/lib/active_model/serializer/adapter.rb b/lib/active_model/serializer/adapter.rb
index 31b6ea57..84649285 100644
--- a/lib/active_model/serializer/adapter.rb
+++ b/lib/active_model/serializer/adapter.rb
@@ -18,11 +18,7 @@ module ActiveModel
       end
 
       def as_json(options = {})
-        if fields = options.delete(:fields)
-          options[:fieldset] = ActiveModel::Serializer::Fieldset.new(fields, serializer.json_key)
-        end
-
-        serializable_hash(options).to_json
+        serializable_hash(options)
       end
     end
   end
diff --git a/lib/active_model/serializer/adapter/json_api.rb b/lib/active_model/serializer/adapter/json_api.rb
index d3d4dd17..ea74fc8c 100644
--- a/lib/active_model/serializer/adapter/json_api.rb
+++ b/lib/active_model/serializer/adapter/json_api.rb
@@ -7,15 +7,20 @@ module ActiveModel
           serializer.root = true
           @hash = {}
           @top = @options.fetch(:top) { @hash }
+
+          if fields = options.delete(:fields)
+            @fieldset = ActiveModel::Serializer::Fieldset.new(fields, serializer.json_key)
+          else
+            @fieldset = options[:fieldset]
+          end
         end
 
         def serializable_hash(options = {})
           @root = (@options[:root] || serializer.json_key.to_s.pluralize).to_sym
-          @fieldset = options[:fieldset]
 
           if serializer.respond_to?(:each)
             @hash[@root] = serializer.map do |s|
-              self.class.new(s, @options.merge(top: @top)).serializable_hash[@root]
+              self.class.new(s, @options.merge(top: @top, fieldset: @fieldset)).serializable_hash[@root]
             end
           else
             @hash[@root] = attributes_for_serializer(serializer, @options)
@@ -94,7 +99,6 @@ module ActiveModel
         private
 
         def attributes_for_serializer(serializer, options)
-
           if fields = @fieldset && @fieldset.fields_for(serializer)
             options[:fields] = fields
           end
diff --git a/test/adapter/json_api/belongs_to_test.rb b/test/adapter/json_api/belongs_to_test.rb
index e25a71d8..048b55b7 100644
--- a/test/adapter/json_api/belongs_to_test.rb
+++ b/test/adapter/json_api/belongs_to_test.rb
@@ -34,6 +34,11 @@ module ActiveModel
             assert_equal([{id: "42", title: 'New Post', body: 'Body'}], @adapter.serializable_hash[:linked][:posts])
           end
 
+          def test_limiting_linked_post_fields
+            @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer, include: 'post', fields: {post: [:title]})
+            assert_equal([{title: 'New Post'}], @adapter.serializable_hash[:linked][:posts])
+          end
+
           def test_include_nil_author
             serializer = PostSerializer.new(@anonymous_post)
             adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer)
diff --git a/test/adapter/json_api/collection_test.rb b/test/adapter/json_api/collection_test.rb
index 922103ea..acea7790 100644
--- a/test/adapter/json_api/collection_test.rb
+++ b/test/adapter/json_api/collection_test.rb
@@ -25,6 +25,15 @@ module ActiveModel
                            { title: "New Post", body: "Body", id: "2", links: { comments: [], author: "1" } }
                          ], @adapter.serializable_hash[:posts])
           end
+
+          def test_limiting_fields
+            @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer, fields: ['title'])
+            assert_equal([
+              { title: "Hello!!", links: { comments: [], author: "1" } },
+              { title: "New Post", links: { comments: [], author: "1" } }
+            ], @adapter.serializable_hash[:posts])
+          end
+
         end
       end
     end
diff --git a/test/adapter/json_api/fieldset_test.rb b/test/adapter/json_api/fieldset_test.rb
deleted file mode 100644
index cc08ba11..00000000
--- a/test/adapter/json_api/fieldset_test.rb
+++ /dev/null
@@ -1,54 +0,0 @@
-require 'test_helper'
-
-module ActiveModel
-  class Serializer
-    class Adapter
-      class JsonApi
-        class FieldsetTest < Minitest::Test
-          def setup
-            @post = Post.new(title: 'New Post', body: 'Body')
-            comment_1 = Comment.new(id: 1, body: 'comment one')
-            comment_2 = Comment.new(id: 2, body: 'comment two')
-            @post.comments = [comment_1, comment_2]
-
-            @serializer = PostSerializer.new(@post)
-            @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer)
-
-          end
-
-          def test_fieldset_with_fields_array
-            fieldset = ActiveModel::Serializer::Fieldset.new(['title'], 'post')
-
-            assert_equal(
-              {:title=>"New Post", :links=>{:comments=>["1", "2"]}}, 
-              @adapter.serializable_hash({fieldset: fieldset})[:posts]
-            )
-          end
-
-          def test_fieldset_with_hash
-            fieldset = ActiveModel::Serializer::Fieldset.new({post: [:body]})
-
-            assert_equal(
-              {:body=>"Body", :links=>{:comments=>["1", "2"]}}, 
-              @adapter.serializable_hash({fieldset: fieldset})[:posts]
-            )
-          end
-
-          def test_fieldset_with_multiple_hashes
-            fieldset = ActiveModel::Serializer::Fieldset.new({post: [:title], comment: [:body]})
-
-            assert_equal(
-              [{:body=>"comment one" }, {:body=>"comment two"}],
-              @adapter.serializable_hash({fieldset: fieldset})[:linked][:comments]
-            )
-
-            #don't understand how this is getting set.
-            @serializer.class._associations[:comments][:options] = {}
-
-          end
-
-        end
-      end
-    end
-  end
-end
\ No newline at end of file
diff --git a/test/adapter/json_api/has_many_test.rb b/test/adapter/json_api/has_many_test.rb
index 975c5b63..e4ce2f62 100644
--- a/test/adapter/json_api/has_many_test.rb
+++ b/test/adapter/json_api/has_many_test.rb
@@ -40,6 +40,14 @@ module ActiveModel
                          ], @adapter.serializable_hash[:linked][:comments])
           end
 
+          def test_limit_fields_of_linked_comments
+            @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer, include: 'comments', fields: {comment: [:body]})
+            assert_equal([
+                           {body: 'ZOMG A COMMENT'},
+                           {body: 'ZOMG ANOTHER COMMENT'}
+                         ], @adapter.serializable_hash[:linked][:comments])
+          end
+
           def test_no_include_linked_if_comments_is_empty
             serializer = PostSerializer.new(@post_without_comments)
             adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer)