Deserialization of null String values in Arrays / Collections not working as expected · Issue #584 · FasterXML/jackson-dataformat-xml (original) (raw)

Environment: Jackson Dataformat XML 2.14.2

We are trying to serialize and deserialize arrays or collections of Strings containing both empty and null values.
We noticed that nulls are handled correctly when serializing:

• null values are rendered as <item />, while empty strings as <item></item>
• enabling ToXmlGenerator.Feature.WRITE_NULLS_AS_XSI_NIL works as expected

When parsing this values back null elements have become empty ("") values.
We tried:

• explicitly enabling FromXmlParser.Feature.PROCESS_XSI_NIL, even though it should be enabled by default
• enabling FromXmlParser.Feature.EMPTY_ELEMENT_AS_NULL
  But we still got empty String values as a result.

Testing showed that with simple String attributes inside a class both null and empty values are correctly handled during deserialization, as expected (see also #354).

The behavior of String values inside collections should be aligned to how String attributes inside objects are handled.

Here's an example:

XmlMapper xmlMapper = new XmlMapper(); xmlMapper.enable( ToXmlGenerator.Feature.WRITE_NULLS_AS_XSI_NIL ); xmlMapper.enable( FromXmlParser.Feature.PROCESS_XSI_NIL );

String string = xmlMapper.writeValueAsString( new String[] { "", "test", null, "test2" } ); // string: testtest2 String[] parsed = xmlMapper.readValue( string, String[].class ); // parsed: ["", "test", "", "test2"]