From 96028a7b9978adb9aa839aa332c35e0c244896aa Mon Sep 17 00:00:00 2001
From: Benjamin Fleischer <github@benjaminfleischer.com>
Date: Mon, 1 May 2017 10:17:48 -0500
Subject: [PATCH 1/2] Document new reflection options; support :foreign_key

---
 docs/general/serializers.md               | 3 +++
 lib/active_model/serializer/reflection.rb | 4 +++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/docs/general/serializers.md b/docs/general/serializers.md
index 1d968183..0606c51d 100644
--- a/docs/general/serializers.md
+++ b/docs/general/serializers.md
@@ -64,6 +64,9 @@ Where:
   - `unless:`
   - `virtual_value:`
   - `polymorphic:` defines if polymorphic relation type should be nested in serialized association.
+  - `type:` the resource type as used by JSON:API, especially on a `belongs_to` relationship.
+  - `class_name:` used to determine `type` when `type` not given
+  - `foreign_key:` used by JSON:API on a `belongs_to` relationship to avoid unnecessarily loading the association object.
 - optional: `&block` is a context that returns the association's attributes.
   - prevents `association_name` method from being called.
   - return value of block is used as the association value.
diff --git a/lib/active_model/serializer/reflection.rb b/lib/active_model/serializer/reflection.rb
index d3daab4b..2e5cc2a1 100644
--- a/lib/active_model/serializer/reflection.rb
+++ b/lib/active_model/serializer/reflection.rb
@@ -9,6 +9,7 @@ module ActiveModel
     # @example
     #   class PostSerializer < ActiveModel::Serializer
     #     has_one :author, serializer: AuthorSerializer
+    #     belongs_to :boss, type: :users, foreign_key: :boss_id
     #     has_many :comments
     #     has_many :comments, key: :last_comments do
     #       object.comments.last(1)
@@ -58,12 +59,13 @@ module ActiveModel
           class_name = options.fetch(:class_name, name.to_s.camelize.singularize)
           class_name.underscore.pluralize.to_sym
         end
-        @foreign_key =
+        @foreign_key = options.fetch(:foreign_key) do
           if collection?
             "#{name.to_s.singularize}_ids".to_sym
           else
             "#{name}_id".to_sym
           end
+        end
       end
 
       # @api public

From ec7b5859f77882892325840eae0716fcaab6c14f Mon Sep 17 00:00:00 2001
From: Benjamin Fleischer <github@benjaminfleischer.com>
Date: Mon, 1 May 2017 10:23:13 -0500
Subject: [PATCH 2/2] Document namespace

---
 docs/general/serializers.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/docs/general/serializers.md b/docs/general/serializers.md
index 0606c51d..5b23ba0f 100644
--- a/docs/general/serializers.md
+++ b/docs/general/serializers.md
@@ -67,6 +67,7 @@ Where:
   - `type:` the resource type as used by JSON:API, especially on a `belongs_to` relationship.
   - `class_name:` used to determine `type` when `type` not given
   - `foreign_key:` used by JSON:API on a `belongs_to` relationship to avoid unnecessarily loading the association object.
+  - `namespace:` used when looking up the serializer and `serializer` is not given.  Falls back to the parent serializer's `:namespace` instance options, which, when present, comes from the render options. See [Rendering#namespace](rendering.md#namespace] for more details.
 - optional: `&block` is a context that returns the association's attributes.
   - prevents `association_name` method from being called.
   - return value of block is used as the association value.