Use sha1 of discussion ID.

app/helpers/notes_helper.rb

@@ -57,7 +57,7 @@ module NotesHelper
 
       data.merge!(
         note_type: LegacyDiffNote.name,
-        discussion_id: discussion_id
+        discussion_id: Digest::SHA1.hexdigest(discussion_id)
       )
     else
       discussion_id = DiffNote.build_discussion_id(
@@ -69,7 +69,7 @@ module NotesHelper
       data.merge!(
         position: position.to_json,
         note_type: DiffNote.name,
-        discussion_id: discussion_id
+        discussion_id: Digest::SHA1.hexdigest(discussion_id)
       )
     end
 

app/models/diff_note.rb

@@ -34,11 +34,11 @@ class DiffNote < Note
   end
 
   def discussion_id
-    @discussion_id ||= self.class.build_discussion_id(noteable_type, noteable_id || commit_id, position)
+    @discussion_id ||= Digest::SHA1.hexdigest(self.class.build_discussion_id(noteable_type, noteable_id || commit_id, position))
   end
 
   def original_discussion_id
-    @original_discussion_id ||= self.class.build_discussion_id(noteable_type, noteable_id || commit_id, original_position)
+    @original_discussion_id ||= Digest::SHA1.hexdigest(self.class.build_discussion_id(noteable_type, noteable_id || commit_id, original_position))
   end
 
   def position=(new_position)

app/models/legacy_diff_note.rb

@@ -22,7 +22,7 @@ class LegacyDiffNote < Note
   end
 
   def discussion_id
-    @discussion_id ||= self.class.build_discussion_id(noteable_type, noteable_id || commit_id, line_code)
+    @discussion_id ||= Digest::SHA1.hexdigest(self.class.build_discussion_id(noteable_type, noteable_id || commit_id, line_code))
   end
 
   def diff_file_hash

app/models/note.rb

@@ -145,9 +145,9 @@ class Note < ActiveRecord::Base
   def discussion_id
     @discussion_id ||=
       if for_merge_request?
-        [:discussion, :note, id].join("-")
+        Digest::SHA1.hexdigest([:discussion, :note, id].join("-"))
       else
-        self.class.build_discussion_id(noteable_type, noteable_id || commit_id)
+        Digest::SHA1.hexdigest(self.class.build_discussion_id(noteable_type, noteable_id || commit_id))
       end
   end