go to post Antoine.Dh · Jan 25 My bad, I simplified my sample too much without actually testing it. I think I found the issue, it seems to happen because I have been using the production test interface, which doesn't seem to allow null values for booleans, unlike strings Sorry for the inconvenience
go to post Antoine.Dh · Jan 19 Oh I see, what I was really missing out there was the XMLPROJECTION = "ELEMENT" Thank you very much for your answer and clearing out some misconceptions about persistent classes Though I have one additional note here: If a class extend Ens.Response or Ens.Request is not necessary to extend %Persistent because is already inherited by Ens.Request/Ens.Response. From what I have read in the IRIS documentation, it is advised to also extend a message class with %Persistent as the primary subclass for performance reasons see https://docs.intersystems.com/iris20231/csp/docbook/DocBook.UI.Page.cls?KEY=EGDV_messages#EGDV_message_body_class If Ens.Request or Ens.Responseis the primary superclass, the messages will be saved in the same table that stores all other requests or responses, and this can adversely affect performance when querying the message tables.