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Default constructor and no setters on data object break serialization

See original GitHub issue

I’ve set up a small app with a REST-Service serving Person objects. Therefore I’m using jackson-jaxrs-json-provider on version 2.7.6.

Person used to have a 3-arg-constructor and getters only and serialisation was working as expected: verbose JSON

Then I added a default constructor to be able to build a client. This broke serialisation: empty JSON

I realised that the serialiser may misses the setters, so I added them. Funny thing, the JSON became leaner: lean JSON

I’ve got three questions:

Why don’t I get any warnings that the setters are missing?
Why do I need the setters at all?
Why is the JSON more verbose when there is no default constructor?

Please let me know, if you need more info 😃

Issue Analytics

State:
Created 7 years ago
Comments:5 (3 by maintainers)

Top GitHub Comments

1reaction

cowtowncodercommented, Aug 15, 2016

Would it be possible to distill information into a single example class, showing what you did, and what you expected to get.

As to warnings, if there is a JSON property that does not have any way to be set (via visible setter or field, or @JsonCreator annotated constructor with @JsonProperty annotated parameters), an exception will be thrown – unless configuration has been changed to ignore such “unknown” properties. I think newer versions of Spring MVC have changed this default, which can easily hide problems.

I have no idea how existence (or not) of default constructor should have any effect on serialization; it should not. Serialization is based on visible getters/fields (either public, or explicitly annotated).

0reactions

PeterWippermanncommented, Oct 4, 2016

Sorry, I can’t provide this. Please go ahead and close this issue…

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