Fix ActivityPub context not being dynamically computed (#11746)

* Fix contexts not being dynamically included

Fixes #11649

* Refactor Note context in serializer

* Refactor Actor serializer

2 files changed, 15 insertions, 6 deletions

diff --git a/app/lib/activitypub/adapter.rb b/app/lib/activitypub/adapter.rb
index 1c58be8c0..cb2ac72d4 100644
--- a/app/lib/activitypub/adapter.rb
+++ b/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]
diff --git a/app/lib/activitypub/serializer.rb b/app/lib/activitypub/serializer.rb
index 07bd8c494..1fdc79310 100644
--- a/app/lib/activitypub/serializer.rb
+++ b/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