I am trying to use formContext.data.entity.addOnPostSave(myFunction) using the Unified Interface in 9.1 on-premise. It doesn't seem to work. I am guessing addOnPostSave is not supported in the Unified Interface for on-premise? It works fine for me in the cloud with the same exact code.
PostSave Event (Client API reference) in model-driven apps - Power Apps | Microsoft Docs
When I try to use it in on load I get it this:
TypeError: formContext.data.entity.addOnPostSave is not a function
at addMessageToOnPostSave (https:///webresources/testonloadnewui:3:29)
at il.executeFunction (https:///uclient/scripts/app.js?v=1.4.3961-v91onpremise:1099:3413)
at il.execute (https:///uclient/scripts/app.js?v=1.4.3961-v91onpremise:1099:3058)
at https:///uclient/scripts/app.js?v=1.4.3961-v91onpremise:102:20676
at i (https:///uclient/scripts/app.js?v=1.4.3961-v91onpremise:219:91)
at V._executeIndividualEvent (https:///uclient/scripts/app.js?v=1.4.3961-v91onpremise:102:20652)
at V._executeEventHandler (https:///uclient/scripts/app.js?v=1.4.3961-v91onpremise:102:18259)
at Object.execute (https:///uclient/scripts/app.js?v=1.4.3961-v91onpremise:102:15586)
at w._executeSyncAction (https:///uclient/scripts/app.js?v=1.4.3961-v91onpremise:719:692)
at w._executeSync (https:///uclient/scripts/app.js?v=1.4.3961-v91onpremise:719:419)