I have my information now but no clue how to add them to the response. I saw suggestions to add custom fields in extensions, but that is not working for me since I am extending a tableStr. (See my simplified code example below).
For a deeper understanding: I want to extend the Status of an ECO Header to the Response.
[ExtensionOf(tableStr(EngChgEngineeringChangeOrderHeaderEntity))] final class EngChgEngineeringChangeOrderHeaderEntity_Extension { [DataEventHandler(tableStr(EngChgEngineeringChangeOrderHeaderEntity), DataEventType::PostedLoad)] public static void EngChgEngineeringChangeOrderHeaderEntity_onPostedLoad(Common _sender, DataEventArgs _eventArgs) { // Get event data as entity EngChgEngineeringChangeOrderHeaderEntity ecoHeaderEntity = _sender as EngChgEngineeringChangeOrderHeaderEntity; // Perform actions in correct company changecompany(ecoHeaderEntity.DataAreaId) { // Read data from EngChgEcmHeader table (to also read Status) EngChgEcmHeader engChgEcmHeader; select RecId, Status from engChgEcmHeader where engChgEcmHeader.RecId == _sender.RecId; if (engChgEcmHeader) { print(engChgEcmHeader.Status); } } } }