It seems that fecthing from memory_store returns a reference to the
object and not a copy. Since the Attributes adapter applies #merge! on
the Hash that is returned from the memory_store, the value in the cache
is also modified.
Status quo in test app:
In Rails
ActionController::Base.cache_store = :memory_store
and then AMS railtie does:
ActiveModelSerializers.config.cache_store = config.action_controller.cache_store
then, in the Railtie
1. ActiveSupport.on_load(:action_controller) fires
- ActiveModelSerializers.config.cache_store #=> nil
- ActionController::Base.cache_store #=> #<ActiveSupport::Cache::FileStore:0x007fe319256760...]
2. After set_configs fires
- ActiveModelSerializers.config.cache_store #+> #<ActiveSupport::Cache::FileStore:0x007fe319256760 ,
3. Tests pass, but notice that we're using the FileStore, not memory store
When we change the config to the test app:
ActionController::Base.cache_store = :memory_store
config = Rails.configuration
config.action_controller.cache_store = :memory_store
then, in the Railtie:
1. ActiveSupport.on_load(:action_controller) fires
- ActiveModelSerializers.config.cache_store #=> nil
- ActionController::Base.cache_store #=> #ActiveSupport::Cache::MemoryStore entries=0, size=0, options={}>]
2. After set_configs fires
- ActiveModelSerializers.config.cache_store #=> :memory_store
3. And we get a lot of failures:
NoMethodError: undefined method `fetch' for :memory_store:Symbol
So, we see that when we set the ActionController::Base.cache_store
directly in our test app, we could set
ActiveModelSerializers.config.cache_store in the :action_controller load
hook, but that would never use the Rails config.
To fix the Rails config, we change the config to the test app:
config = Rails.configuration
config.action_controller.cache_store = :memory_store
and then AMS railtie does:
ActiveModelSerializers.config.cache_store = ActiveSupport::Cache.lookup_store(config.action_controller.cache_store
ActiveSupport.on_load(:action_controller) do
::ActiveModelSerializers.config.cache_store = cache_store
end
then
1. After set_configs fires
- ActiveModelSerializers.config.cache_store #=> <#ActiveSupport::Cache::MemoryStore, object_id 70207113611740
2. ActiveSupport.on_load(:action_controller) fires
- ActionController::Base.cache_store #=> <#ActiveSupport::Cache::MemoryStore, object_id 70207106279660
- ActiveModelSerializers.config.cache_store #=> <#ActiveSupport::Cache::MemoryStore, object_id 70207106279660
(notice the object_id changed)
3. And we get a failure:
1) Failure:
ActiveModelSerializers::CacheTest#test_associations_cache_when_updated
[active_model_serializers/test/cache_test.rb:141]:
--- expected
+++ actual
@@ -1 +1 @@
-{:id=>"post", :title=>"New Post", :body=>"Body"}
+{:id=>"post", :title=>"New Post", :body=>"Body", :comments=>[{:id=>2, :body=>"ZOMG A NEW COMMENT"}], :blog=>{:id=>999, :name=>"Custom blog"}, :author=>{:id=>"author", :name=>"Joao M. D. Moura"}}
If we take out the on_load(:action_controller) hook, we get a ton of
failures. So clearly, our code expects the controller cache to be the
same as the serializer cache.
So, we make sure we use an on_load(:action_controller) hook that runs
after set_configs
And look at the test and see it is filled with direct calls to ActionController::Base.cache_store
assert_equal(new_comment_serializer.attributes, ActionController::Base.cache_store.fetch(new_comment.cache_key))
assert_equal(@post_serializer.attributes, ActionController::Base.cache_store.fetch(@post.cache_key))
But that's not a problem in this case, since they're the same object.
For now, let's remove the :memory_store setting and use the default FileStore
