Record with no-arg constructor with does not deserialise correctly

[dansiviter]

Describe the bug
If a record has a no-arg constructor when deserialised the optional is always <empty>.

To Reproduce
An example is available here.

Expected behavior
The correct constructor for the record is selected.

System information:

• OS: Windows 11
• Java Version: 17
• Yasson Version: 3.0.0-RC1

Additional context
N/A

[dansiviter]

Updates as I originally thought it was due to Optional but appears it happens every time.

[Verdent]

Hi Dan, this is happening due to default empty constructor you are having in all of the records. Yasson is trying to find @JsonbCreator annotated constructor/factory and finds none, tries to find not annotated constructor to use, but there are multiple of them and it is not clear which one should be used. But since there is default constructor, if backs to use that. If you remove empty constructor, everything will work as expected. Or if you need that default constructor for some reason, you can overwrite the parametrized one and mark it as @JsonbCreator and Yasson will prioritize this one. This is possible workaround for now.

Now I am thinking whether we should throw an exception in cases when record do have multiple constructors (including the default one) and none of them is marked as @JsonbCreator. It might possibly make sense for records. Record processing is already failing when handling multiple parametrized constructors and have none annotated as creator.

[dansiviter]

From RecordTest.java:L69 it does suggest that it should throw an exception but I'm not seeing that behaviour in 3.0.0-RC1. 🤔

[dansiviter]

I've just checked and it's due to default no-args constructor behaviour of records. I'd argue a no-arg constructor is a pointless record so should throw an exception regardless.

[Verdent]

Exactly my thought when I was analyzing it yesterday. I will make the needed change :-)

[Verdent]

It does fail for multiple constructors, but since it is taking nearly the same processing path as regular class, I forgot to make it to fail when default constructor is present. It backs to use that and does not fail in this case. :-)