Internally, JSON objects are deserialized into ADO.NET objects (in Java, you can find those within the
com.aspose.words.net.System.Data package). In you example,
atStrumentiByCodStrum is deserialized into a collection of rows related to the
children table. Although
atStrumentiByCodStrum is set to null for the first item in your JSON file, internally, it becomes an empty collection of rows that is not null, so comparison against null does not work.
desShort only when
atStrumentiByCodStrum represents a non-empty collection of rows, you can use the following syntax:
<<if [saldo.atStrumentiByCodStrum.count() == 1]>>
I have modified your template to show this. Please check testJsonNull Modified.docx (248.0 KB).