Conversion of MissingNode throws JsonProcessingException

[ludgerb]

According to the documentation about MissingNode the following holds:

In most respects this placeholder node will act as NullNode; for example, for purposes of value conversions, value is considered to be null and represented as value zero when used for numeric conversions.

While this holds true for most operation, this fails when converting a json tree containing a MissingNode to a Pojo.

Version Information

2.18.0

Reproduction

  @Test
  void testTreeToValue() throws JsonProcessingException {
    ObjectMapper objectMapper = new ObjectMapper();

    // Success
    var result = assertDoesNotThrow(() -> objectMapper.treeToValue(NullNode.getInstance(), Object.class));
    assertNull(result);

    // Fails
    result = assertDoesNotThrow(() -> objectMapper.treeToValue(MissingNode.getInstance(), Object.class));
    assertNull(result);
  }

Expected behavior

Expected behavior:
converting a MissingNode should behave the same as converting the NullNode

Observed behavior:
converting a NullNode returns a null reference.
converting a MissingNode throws a JsonProcessingException.

[cowtowncoder]

Sounds sub-optimal. I'll need to think about expected behavior: probably should be converted to "absent value" (which most often is null). It'd be easier to simply map to null but... I'll see.

[ludgerb]

Hi Cowtowncoder, thank you for considering

I admit my expected behavior is only because of the documentation I cited. It does not necessarily have to be null.
But current behavior of throwing an exception is "sub-optimal".

For comparison:
If you serialize a JsonTree containing a MissingNode to a String or byte stream as an intermediate operation and then de-serialize that stream to a Pojo, you get a null value.

[cowtowncoder]

Right, 100% agreed on now throwing exception. I think I'll go with null as the first step; can re-consider wrt getAbsentValue() at a later point.
(note: "absent value" is in almost cases null -- just not for primitives and Optional(-style) values).