Move serializer caching from adapter

CHANGELOG.md

@@ -34,6 +34,7 @@ Fixes:
 - [#1488](https://github.com/rails-api/active_model_serializers/pull/1488) Require ActiveSupport's string inflections (@nate00)
 
 Misc:
+- [#1471](https://github.com/rails-api/active_model_serializers/pull/1471) [Cleanup] Serializer caching is its own concern. (@bf4)
 - [#1482](https://github.com/rails-api/active_model_serializers/pull/1482) Document JSON API implementation defs and progress in class. (@bf4)
 - [#1551](https://github.com/rails-api/active_model_serializers/pull/1551) Added codebeat badge (@korzonek)
 - [#1527](https://github.com/rails-api/active_model_serializers/pull/1527) Refactor fragment cache class. (@groyoh)

lib/active_model/serializer.rb

@@ -48,9 +48,12 @@ def self.serializer_for(resource, options = {})
     # @see ActiveModelSerializers::Adapter.lookup
     # Deprecated
     def self.adapter
-      warn 'Calling adapter method in Serializer, please use the ActiveModelSerializers::Adapter.configured_adapter'
       ActiveModelSerializers::Adapter.lookup(config.adapter)
     end
+    class << self
+      extend ActiveModelSerializers::Deprecate
+      deprecate :adapter, 'ActiveModelSerializers::Adapter.configured_adapter'
+    end
 
     # @api private
     def self.serializer_lookup_chain_for(klass)

lib/active_model/serializer/attributes.rb

@@ -68,7 +68,7 @@ def _attributes
         # @api private
         # maps attribute value to explict key name
         # @see Serializer::attribute
-        # @see Adapter::FragmentCache#fragment_serializer
+        # @see FragmentCache#fragment_serializer
         def _attributes_keys
           _attributes_data
             .each_with_object({}) do |(key, attr), hash|

lib/active_model_serializers.rb

@@ -5,6 +5,8 @@
 module ActiveModelSerializers
   extend ActiveSupport::Autoload
   autoload :Model
+  autoload :CachedSerializer
+  autoload :FragmentCache
   autoload :Callbacks
   autoload :Deserialization
   autoload :Logging

lib/active_model_serializers/adapter.rb

@@ -3,8 +3,6 @@ module Adapter
     UnknownAdapterError = Class.new(ArgumentError)
     ADAPTER_MAP = {} # rubocop:disable Style/MutableConstant
     private_constant :ADAPTER_MAP if defined?(private_constant)
-    require 'active_model_serializers/adapter/fragment_cache'
-    require 'active_model_serializers/adapter/cached_serializer'
 
     class << self # All methods are class functions
       def new(*args)

lib/active_model_serializers/adapter/attributes.rb

@@ -17,10 +17,6 @@ def serializable_hash(options = nil)
         end
       end
 
-      def fragment_cache(cached_hash, non_cached_hash)
-        Json::FragmentCache.new.fragment_cache(cached_hash, non_cached_hash)
-      end
-
       private
 
       def serializable_hash_for_collection(options)

lib/active_model_serializers/adapter/base.rb

@@ -23,8 +23,8 @@ def as_json(options = nil)
         hash
       end
 
-      def fragment_cache(*_args)
-        fail NotImplementedError, 'This is an abstract method. Should be implemented at the concrete adapter.'
+      def fragment_cache(cached_hash, non_cached_hash)
+        non_cached_hash.merge cached_hash
       end
 
       def cache_check(serializer)

lib/active_model_serializers/adapter/json.rb

@@ -1,19 +1,10 @@
 module ActiveModelSerializers
   module Adapter
     class Json < Base
-      extend ActiveSupport::Autoload
-      autoload :FragmentCache
-
       def serializable_hash(options = nil)
         options ||= {}
         { root => Attributes.new(serializer, instance_options).serializable_hash(options) }
       end
-
-      private
-
-      def fragment_cache(cached_hash, non_cached_hash)
-        ActiveModelSerializers::Adapter::Json::FragmentCache.new.fragment_cache(cached_hash, non_cached_hash)
-      end
     end
   end
 end

lib/active_model_serializers/adapter/json_api.rb

@@ -22,7 +22,6 @@ module ActiveModelSerializers
   module Adapter
     class JsonApi < Base
       extend ActiveSupport::Autoload
-      autoload :FragmentCache
       autoload :Jsonapi
       autoload :ResourceIdentifier
       autoload :Relationship
@@ -169,7 +168,14 @@ def failure_document
 
       def fragment_cache(cached_hash, non_cached_hash)
         root = false if instance_options.include?(:include)
-        FragmentCache.new.fragment_cache(root, cached_hash, non_cached_hash)
+        core_cached       = cached_hash.first
+        core_non_cached   = non_cached_hash.first
+        no_root_cache     = cached_hash.delete_if { |key, _value| key == core_cached[0] }
+        no_root_non_cache = non_cached_hash.delete_if { |key, _value| key == core_non_cached[0] }
+        cached_resource   = (core_cached[1]) ? core_cached[1].deep_merge(core_non_cached[1]) : core_non_cached[1]
+        hash = root ? { root => cached_resource } : cached_resource
+
+        hash.deep_merge no_root_non_cache.deep_merge no_root_cache
       end
 
       protected