Problem is that your path does not lead you to one single ApplicationUser, but to a list of ApplicationUsers. In your xpath you go from entity UserRole to ApplicationUser, and since many user can have that particular UserRole, you get a list of ApplicationUser, hence you will not be able to get the FullName.
Wrap your datagrid in a dataview which has datasource “ApplicationUser_GetByCurrentUser”, then your xpath will be "FullName = ApplicationUser.FullName”.
The flow will look something like this:
I hope you are trying to apply the Xpath constraint on data containers. If yes please the below. If it’s different case let me know
If its direct attribute, you need not to use CurrentObject, just pass the attribute in between [ ]
I'd like to use the attribute of the RowManagerNonPersistable for the xpath
Okay then you can try this :