Fix #955

lib/active_model/serializer.rb

@@ -222,10 +222,22 @@ def each_association(&block)
         serializer_class = ActiveModel::Serializer.serializer_for(association_value, association_options)
 
         if serializer_class
-          serializer = serializer_class.new(
-            association_value,
-            options.except(:serializer).merge(serializer_from_options(association_options))
-          )
+          begin
+            serializer = serializer_class.new(
+              association_value,
+              options.except(:serializer).merge(serializer_from_options(association_options))
+            )
+          rescue NoMethodError
+            # 1. Failure to serialize an element in a collection, e.g. [ {hi: "Steve" } ] will fail
+            #    with NoMethodError when the ArraySerializer finds no serializer for the hash { hi: "Steve" },
+            #    and tries to call new on that nil.
+            # 2. Convert association_value to hash using implicit as_json
+            # 3. Set as virtual value (serializer is nil)
+            # 4. Consider warning when this happens
+            virtual_value = association_value
+            virtual_value = virtual_value.as_json if virtual_value.respond_to?(:as_json)
+            association_options[:association_options][:virtual_value] = virtual_value
+          end
         elsif !association_value.nil? && !association_value.instance_of?(Object)
           association_options[:association_options][:virtual_value] = association_value
         end

test/adapter/json/has_many_test.rb

@@ -8,7 +8,7 @@ class HasManyTestTest < Minitest::Test
           def setup
             ActionController::Base.cache_store.clear
             @author = Author.new(id: 1, name: 'Steve K.')
-            @post = Post.new(title: 'New Post', body: 'Body')
+            @post = Post.new(id: 42, 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]
@@ -17,16 +17,28 @@ def setup
             @second_comment.post = @post
             @blog = Blog.new(id: 1, name: "My Blog!!")
             @post.blog = @blog
-
-            @serializer = PostSerializer.new(@post)
-            @adapter = ActiveModel::Serializer::Adapter::Json.new(@serializer)
+            @tag = Tag.new(id: 1, name: "#hash_tag")
+            @post.tags = [@tag]
           end
 
           def test_has_many
+            serializer = PostSerializer.new(@post)
+            adapter = ActiveModel::Serializer::Adapter::Json.new(serializer)
             assert_equal([
                            {id: 1, body: 'ZOMG A COMMENT'},
                            {id: 2, body: 'ZOMG ANOTHER COMMENT'}
-                         ], @adapter.serializable_hash[:post][:comments])
+                         ], adapter.serializable_hash[:post][:comments])
+          end
+
+          def test_has_many_with_no_serializer
+            serializer = PostWithTagsSerializer.new(@post)
+            adapter = ActiveModel::Serializer::Adapter::Json.new(serializer)
+            assert_equal({
+              id: 42,
+              tags: [
+                {"attributes"=>{"id"=>1, "name"=>"#hash_tag"}}
+              ]
+            }, adapter.serializable_hash[:post_with_tags])
           end
         end
       end

test/adapter/json_api/has_many_test.rb

@@ -27,7 +27,8 @@ def setup
             @blog.articles = [@post]
             @post.blog = @blog
             @post_without_comments.blog = nil
-
+            @tag = Tag.new(id: 1, name: "#hash_tag")
+            @post.tags = [@tag]
             @serializer = PostSerializer.new(@post)
             @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer)
           end
@@ -103,6 +104,20 @@ def test_include_type_for_association_when_different_than_name
             }
             assert_equal expected, actual
           end
+
+          def test_has_many_with_no_serializer
+            serializer = PostWithTagsSerializer.new(@post)
+            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer)
+            assert_equal({
+              data: {
+                id: "1",
+                type: "posts",
+                relationships: {
+                  tags: {:data=>nil}
+                }
+              }
+            }, adapter.serializable_hash)
+          end
         end
       end
     end

test/fixtures/poro.rb

@@ -77,6 +77,7 @@ class ProfilePreviewSerializer < ActiveModel::Serializer
 User     = Class.new(Model)
 Location = Class.new(Model)
 Place    = Class.new(Model)
+Tag      = Class.new(Model)
 
 module Spam; end
 Spam::UnrelatedLink = Class.new(Model)
@@ -219,6 +220,12 @@ def self.root_name
   belongs_to :author, serializer: AuthorPreviewSerializer
 end
 
+PostWithTagsSerializer = Class.new(ActiveModel::Serializer) do
+  attributes :id
+
+  has_many :tags
+end
+
 Spam::UnrelatedLinkSerializer = Class.new(ActiveModel::Serializer) do
   attributes :id
 end

test/serializers/associations_test.rb

@@ -29,8 +29,10 @@ def setup
         @author.roles = []
         @blog = Blog.new({ name: 'AMS Blog' })
         @post = Post.new({ title: 'New Post', body: 'Body' })
+        @tag = Tag.new({name: '#hashtagged'})
         @comment = Comment.new({ id: 1, body: 'ZOMG A COMMENT' })
         @post.comments = [@comment]
+        @post.tags = [@tag]
         @post.blog = @blog
         @comment.post = @post
         @comment.author = nil
@@ -65,6 +67,14 @@ def test_has_many_and_has_one
         end
       end
 
+      def test_has_many_with_no_serializer
+        PostWithTagsSerializer.new(@post).each_association do |name, serializer, options|
+          assert_equal name, :tags
+          assert_equal serializer, nil
+          assert_equal options, {:virtual_value=>[{"attributes"=>{"name"=>"#hashtagged"}}]}
+        end
+      end
+
       def test_serializer_options_are_passed_into_associations_serializers
         @post_serializer.each_association do |name, association|
           if name == :comments