Fix ActivityPub context not being dynamically computed (#11746)

* Fix contexts not being dynamically included

Fixes #11649

* Refactor Note context in serializer

* Refactor Actor serializer

app/lib/activitypub/adapter.rb

@@ -32,22 +32,23 @@ class ActivityPub::Adapter < ActiveModelSerializers::Adapter::Base
   end
 
   def serializable_hash(options = nil)
+    named_contexts     = {}
+    context_extensions = {}
     options         = serialization_options(options)
-    serialized_hash = serializer.serializable_hash(options)
+    serialized_hash = serializer.serializable_hash(options.merge(named_contexts: named_contexts, context_extensions: context_extensions))
     serialized_hash = serialized_hash.select { |k, _| options[:fields].include?(k) } if options[:fields]
     serialized_hash = self.class.transform_key_casing!(serialized_hash, instance_options)
 
-    { '@context' => serialized_context }.merge(serialized_hash)
+    { '@context' => serialized_context(named_contexts, context_extensions) }.merge(serialized_hash)
   end
 
   private
 
-  def serialized_context
+  def serialized_context(named_contexts_map, context_extensions_map)
     context_array = []
 
-    serializer_options = serializer.send(:instance_options) || {}
-    named_contexts     = [:activitystreams] + serializer._named_contexts.keys + serializer_options.fetch(:named_contexts, {}).keys
-    context_extensions = serializer._context_extensions.keys + serializer_options.fetch(:context_extensions, {}).keys
+    named_contexts     = [:activitystreams] + named_contexts_map.keys
+    context_extensions = context_extensions_map.keys
 
     named_contexts.each do |key|
       context_array << NAMED_CONTEXT_MAP[key]

app/lib/activitypub/serializer.rb

@@ -27,4 +27,12 @@ class ActivityPub::Serializer < ActiveModel::Serializer
       _context_extensions[extension_name] = true
     end
   end
+
+  def serializable_hash(adapter_options = nil, options = {}, adapter_instance = self.class.serialization_adapter_instance)
+    unless adapter_options&.fetch(:named_contexts, nil).nil?
+      adapter_options[:named_contexts].merge!(_named_contexts)
+      adapter_options[:context_extensions].merge!(_context_extensions)
+    end
+    super(adapter_options, options, adapter_instance)
+  end
 end

app/serializers/activitypub/actor_serializer.rb

@@ -6,7 +6,7 @@ class ActivityPub::ActorSerializer < ActivityPub::Serializer
   context :security
 
   context_extensions :manually_approves_followers, :featured, :also_known_as,
-                     :moved_to, :property_value, :hashtag, :emoji, :identity_proof,
+                     :moved_to, :property_value, :identity_proof,
                      :discoverable
 
   attributes :id, :type, :following, :followers,
@@ -138,6 +138,8 @@ class ActivityPub::ActorSerializer < ActivityPub::Serializer
   end
 
   class TagSerializer < ActivityPub::Serializer
+    context_extensions :hashtag
+
     include RoutingHelper
 
     attributes :type, :href, :name

app/serializers/activitypub/note_serializer.rb

@@ -1,8 +1,7 @@
 # frozen_string_literal: true
 
 class ActivityPub::NoteSerializer < ActivityPub::Serializer
-  context_extensions :atom_uri, :conversation, :sensitive,
-                     :hashtag, :emoji, :focal_point, :blurhash
+  context_extensions :atom_uri, :conversation, :sensitive
 
   attributes :id, :type, :summary,
              :in_reply_to, :published, :url,
@@ -151,6 +150,8 @@ class ActivityPub::NoteSerializer < ActivityPub::Serializer
   end
 
   class MediaAttachmentSerializer < ActivityPub::Serializer
+    context_extensions :blurhash, :focal_point
+
     include RoutingHelper
 
     attributes :type, :media_type, :url, :name, :blurhash
@@ -198,6 +199,8 @@ class ActivityPub::NoteSerializer < ActivityPub::Serializer
   end
 
   class TagSerializer < ActivityPub::Serializer
+    context_extensions :hashtag
+
     include RoutingHelper
 
     attributes :type, :href, :name

config/initializers/active_model_serializers.rb

@@ -3,22 +3,3 @@ ActiveModelSerializers.config.tap do |config|
 end
 
 ActiveSupport::Notifications.unsubscribe(ActiveModelSerializers::Logging::RENDER_EVENT)
-
-class ActiveModel::Serializer::Reflection
-  # We monkey-patch this method so that when we include associations in a serializer,
-  # the nested serializers can send information about used contexts upwards back to
-  # the root. We do this via instance_options because the nesting can be dynamic.
-  def build_association(parent_serializer, parent_serializer_options, include_slice = {})
-    serializer = options[:serializer]
-
-    parent_serializer_options.merge!(named_contexts: serializer._named_contexts, context_extensions: serializer._context_extensions) if serializer.respond_to?(:_named_contexts)
-
-    association_options = {
-      parent_serializer: parent_serializer,
-      parent_serializer_options: parent_serializer_options,
-      include_slice: include_slice,
-    }
-
-    ActiveModel::Serializer::Association.new(self, association_options)
-  end
-end

spec/lib/activitypub/activity/update_spec.rb

@@ -19,7 +19,7 @@ RSpec.describe ActivityPub::Activity::Update do
   end
 
   let(:actor_json) do
-    ActiveModelSerializers::SerializableResource.new(modified_sender, serializer: ActivityPub::ActorSerializer, key_transform: :camel_lower).as_json
+    ActiveModelSerializers::SerializableResource.new(modified_sender, serializer: ActivityPub::ActorSerializer, adapter: ActivityPub::Adapter).as_json
   end
 
   let(:json) do