The following error occur when retrieving data: The property does not allow null value: Object_Ref.
Cause & Solution:
When converting the DataWindow to the model, the nullable property is not correctly set. You can search for the problematic object (for example, Object_Ref) in the exported models in the PowerServer C# solution, and modify it to allow null values. For example,
Change
[Key]
[DwColumn("disp", "object_ref")]
public long Object_Ref { get; set; }
To
[Key]
[DwColumn("disp", "object_ref")]
public long? Object_Ref { get; set; }
