Add serializer to association block context

[bf4]

Perhaps there some method on the serializer that I want to use in the association block.
I couldn't because it is being evaluated in the 'Reflection' object.

• Add serializer to Reflection evaluation binding
• Test that we can a serializer method from an association block
• Document usage
• Add changelog

[groyoh]

Just as a proposal block_value = instance_exec(serializer, &block) would also be possible I guess and would be less "hidden".

[bf4]

@groyoh oh yeah, I forgot you can do that

[bf4]

oh, but then someone would need to add a block param.

-             has_many :roles do
+             has_many :roles do |serializer|
                meta count: object.posts.count
                serializer.cached_roles
              end

it's kind of nicer without that, right?

[bf4]

diff --git a/lib/active_model/serializer/reflection.rb b/lib/active_model/serializer/reflection.rb
index 5257a90..1c70527 100644
--- a/lib/active_model/serializer/reflection.rb
+++ b/lib/active_model/serializer/reflection.rb
@@ -59,11 +59,9 @@ module ActiveModel
       def value(serializer)
         @object = serializer.object
         @scope = serializer.scope
-        # Add '@serializer' to binding for use in association block as 'serializer'
-        @serializer = serializer

         if block
-          block_value = instance_eval(&block)
+          block_value = instance_exec(serializer, &block)
           if block_value == :nil
             serializer.read_attribute_for_serialization(name)
           else
@@ -119,7 +117,7 @@ module ActiveModel

       protected

-      attr_accessor :object, :scope, :serializer
+      attr_accessor :object, :scope

       private

diff --git a/test/adapter/json_api/relationships_test.rb b/test/adapter/json_api/relationships_test.rb
index bf47a4e..5fa0de8 100644
--- a/test/adapter/json_api/relationships_test.rb
+++ b/test/adapter/json_api/relationships_test.rb
@@ -38,7 +38,7 @@ module ActiveModel
               end
             end

-            has_many :roles do
+            has_many :roles do |serializer|
               meta count: object.posts.count
               serializer.cached_roles
             end

[groyoh]

Yeah, my point was that just using instance_eval "hides" the fact that we can use serializer (also object and scope). With instance_exec you know that you're using the parameter. And if you don't need to use serializer, you can simply not add any parameter to your block.

To me:

has_many :comments do |serializer|
  meta count: serializer.object.comments.count
end

is easier to understand than:

has_many :comments do
  meta count: object.comments.count
end

You don't need to look through the doc/code to know what are available within the block. But that's maybe just my opinion. And yes, the second version is a bit less verbose and nicer. 😉

In the end, I'm fine with any solution. I just wanted to point it out ;)

[bf4]

@groyoh I like the idea. Added a commit

[groyoh]

Why is appveyor taking so long?

[bf4]

@groyoh done now

[bf4]

Resolves #1976