Remove data from cached resource fragments (#1380)

* Remove `data` from cached resource fragments

* Create a new hash using `transform_values`

lib/jsonapi/cached_response_fragment.rb

@@ -51,8 +51,8 @@ def initialize(resource_klass, id, type, context, fetchable_fields, relationship
       @fetchable_fields = Set.new(fetchable_fields)
 
       # Relationships left uncompiled because we'll often want to insert included ids on retrieval
-      @relationships = relationships
-
+      # Remove the data since that should not be cached
+      @relationships = relationships&.transform_values {|v| v.delete_if {|k, _v| k == 'data'} }
       @links_json = CompiledJson.of(links_json)
       @attributes_json = CompiledJson.of(attributes_json)
       @meta_json = CompiledJson.of(meta_json)

test/controllers/controller_test.rb

@@ -304,6 +304,22 @@ def test_index_filter_not_allowed
     JSONAPI.configuration.allow_filter = true
   end
 
+  def test_cached_result_does_not_include_relationship_data
+    JSONAPI.configuration.resource_cache = ActiveSupport::Cache::MemoryStore.new
+    JSONAPI.configuration.default_caching = true
+
+    get :show, params: {id: '1', include: 'author'}
+    assert_response :success
+    assert json_response['data']['relationships']['author']['data']
+
+    get :show, params: {id: '1'}
+    assert_response :success
+    refute json_response['data']['relationships']['author']['data']
+  ensure
+    JSONAPI.configuration.resource_cache = nil
+    JSONAPI.configuration.default_caching = false
+  end
+
   def test_index_include_one_level_query_count
     assert_query_count(4) do
       assert_cacheable_get :index, params: {include: 'author'}