Create object attachments for posts with image uploads

Author: angusmcleod

app/models/concerns/discourse_activity_pub/ap/model_callbacks.rb

@@ -144,6 +144,20 @@ def update_activity_pub_activity_object
         if performing_activity.create? || performing_activity.update?
           performing_activity_object.name = self.activity_pub_name if self.activity_pub_name
           performing_activity_object.content = self.activity_pub_content
+
+          if self.activity_pub_attachments.present?
+            self.activity_pub_attachments.each do |attachment|
+              performing_activity_object.attachments.build(
+                object_id: performing_activity_object.id,
+                object_type: performing_activity_object.class.name,
+                ap_type: attachment.type,
+                url: attachment.url.href,
+                name: attachment.name,
+                media_type: attachment.media_type,
+              )
+            end
+          end
+
           performing_activity_object.save!
         end
       end

plugin.rb

@@ -555,6 +555,19 @@
     @activity_pub_topic_trashed ||= Topic.with_deleted.find_by(id: self.topic_id)
   end
   add_to_class(:post, :activity_pub_object_id) { activity_pub_object&.ap_id }
+  add_to_class(:post, :activity_pub_attachments) do
+    uploads
+      .where(extension: FileHelper.supported_images)
+      .map do |upload|
+        DiscourseActivityPub::AP::Object::Image.new(
+          json: {
+            name: upload.original_filename,
+            url: UrlHelper.absolute(upload.url),
+            mediaType: MiniMime.lookup_by_extension(upload.extension).content_type,
+          },
+        )
+      end
+  end
 
   add_model_callback(:post, :after_destroy) do
     # We need these to create a Delete activity when the post is actually destroyed

spec/models/post_spec.rb

@@ -2817,5 +2817,56 @@ def perform_delete
         end
       end
     end
+
+    context "with uploads" do
+      let!(:topic) { Fabricate(:topic, category: category) }
+      let!(:user) { Fabricate(:user) }
+
+      before do
+        toggle_activity_pub(category, publication_type: "full_topic")
+        topic.create_activity_pub_collection!
+      end
+
+      def perform_create
+        post.perform_activity_pub_activity(:create)
+        post.reload
+      end
+
+      context "with a supported media type" do
+        let!(:post) { Fabricate(:post_with_uploaded_image, topic: topic) }
+
+        before do
+          DiscourseActivityPub::ActorHandler.update_or_create_actor(post.user)
+          post.link_post_uploads
+        end
+
+        it "creates attachments" do
+          perform_create
+          expect(post.activity_pub_object.attachments.size).to eq(1)
+          expect(post.activity_pub_object.attachments.first.ap_type).to eq("Image")
+          expect(post.activity_pub_object.attachments.first.name).to eq(
+            post.uploads.first.original_filename,
+          )
+          expect(post.activity_pub_object.attachments.first.media_type).to eq("image/png")
+          expect(post.activity_pub_object.attachments.first.url).to eq(
+            UrlHelper.absolute(post.uploads.first.url),
+          )
+        end
+      end
+
+      context "with an unsupported media type" do
+        let!(:post) { Fabricate(:post_with_an_attachment, topic: topic) }
+
+        before do
+          DiscourseActivityPub::ActorHandler.update_or_create_actor(post.user)
+          post.link_post_uploads
+        end
+
+        it "does not create attachments" do
+          perform_create
+          expect(post.activity_pub_object.attachments.size).to eq(0)
+        end
+      end
+    end
   end
 end