Allow to pass context around serializers

lib/active_model/array_serializer.rb

@@ -14,6 +14,7 @@ module ActiveModel
 
     def initialize(object, options={})
       @object          = object
+      @context         = options[:context]
       @scope           = options[:scope]
       @root            = options.fetch(:root, self.class._root)
       @meta_key        = options[:meta_key] || :meta
@@ -21,7 +22,7 @@ module ActiveModel
       @each_serializer = options[:each_serializer]
       @resource_name   = options[:resource_name]
     end
-    attr_accessor :object, :scope, :root, :meta_key, :meta
+    attr_accessor :object, :context, :scope, :root, :meta_key, :meta
 
     def json_key
       if root.nil?
@@ -33,7 +34,7 @@ module ActiveModel
 
     def serializer_for(item)
       serializer_class = @each_serializer || Serializer.serializer_for(item) || DefaultSerializer
-      serializer_class.new(item, scope: scope)
+      serializer_class.new(item, context: context, scope: scope)
     end
 
     def serializable_object

lib/active_model/serializer.rb

@@ -103,13 +103,14 @@ end
 
     def initialize(object, options={})
       @object        = object
+      @context       = options[:context]
       @scope         = options[:scope]
       @root          = options.fetch(:root, self.class._root)
       @meta_key      = options[:meta_key] || :meta
       @meta          = options[@meta_key]
       @wrap_in_array = options[:_wrap_in_array]
     end
-    attr_accessor :object, :scope, :root, :meta_key, :meta
+    attr_accessor :object, :context, :scope, :root, :meta_key, :meta
 
     def json_key
       if root == true || root.nil?
@@ -166,7 +167,7 @@ end
 
     def build_serializer(association)
       object = send(association.name)
-      association.build_serializer(object, scope: scope)
+      association.build_serializer(object, context: context, scope: scope)
     end
 
     def serialize(association)

test/unit/active_model/array_serializer/context_test.rb

@@ -0,0 +1,19 @@
+require 'test_helper'
+
+module ActiveModel
+  class ArraySerializer
+    class ContextTest < ActiveModel::TestCase
+      def test_context_using_a_hash
+        serializer = ArraySerializer.new(nil, context: { a: 1, b: 2 })
+        assert_equal(1, serializer.context[:a])
+        assert_equal(2, serializer.context[:b])
+      end
+
+      def test_context_using_an_object
+        serializer = ArraySerializer.new(nil, context: Struct.new(:a, :b).new(1, 2))
+        assert_equal(1, serializer.context.a)
+        assert_equal(2, serializer.context.b)
+      end
+    end
+  end
+end

test/unit/active_model/serializer/context_test.rb

@@ -0,0 +1,19 @@
+require 'test_helper'
+
+module ActiveModel
+  class Serializer
+    class ContextTest < ActiveModel::TestCase
+      def test_context_using_a_hash
+        serializer = UserSerializer.new(nil, context: { a: 1, b: 2 })
+        assert_equal(1, serializer.context[:a])
+        assert_equal(2, serializer.context[:b])
+      end
+
+      def test_context_using_an_object
+        serializer = UserSerializer.new(nil, context: Struct.new(:a, :b).new(1, 2))
+        assert_equal(1, serializer.context.a)
+        assert_equal(2, serializer.context.b)
+      end
+    end
+  end
+end