Add support for java.beans.Transient

[tmortagne]

java.beans.Transient is a new Java bean annotation introduced in Java 7 which has pretty much the same meaning as transient keyword except that you can put it on methods to ignore some getters for example.

I guess the issue is that Jackson follow Java bean but does not actually use java.beans.Introspector and impossible to support this annotation before Jackson move to Java 7 (which is not the case from what I understood from http://wiki.fasterxml.com/JacksonDownload).

Any idea what would be the cleanest to support that in the meantime ? I tough about setting a custom visibility checker but maybe there is a better way.

[cowtowncoder]

First of all, thank you for reporting this. I was not aware of this addition.

The technical answer is that sub-classing JacksonAnnotationIntrospector, overriding hasIgnoralMarker() method (or whatever the name was, something like that) to check for annotation, return Boolean.TRUE.

Check can not be added in jackson-databind yet, as it only requires Java 6 for current versions (at least until 2.6). When baseline is increased (we will probably discuss that for Jackson 2.7), check could be directly added.
Until then, jackson-datatype-jdk7 project would be the natural place for this feature; it does not yet define custom annnotation introspector, but it could. And then it would be matter of documentation to let users know to register alternate introspector; or make it auto-register.

[tmortagne]

Actually I did not knew about jackson-datatype-jdk7, glad I ear about it before reporting features it adds :)

[cowtowncoder]

No problem, right now it's quite minimal. But there is also jackson-datatype-jdk8, as well as jackson-datatype-jsr310 (Java 8 date time), so seemed appropriate to have sort of convention of adding features for new JDKs.

[cowtowncoder]

Discussions on-going to make Jackson 2.7 require Java 7 / JDK 1.7. If so, could be added in core jackson-databind, which would be good.

[cowtowncoder]

Ok: Jackson 2.7 will require Java 7, so we can actually use this marker annotation.

One potential concern I have is that although it would be possible to simply consider this an alias of @JsonIgnore, this is not quite what keyword transient does, because by default it only prevents use of the particular field marked, unless MapperFeature.PROPAGATE_TRANSIENT_MARKER is enabled.
So the annotation should probably work the same way. But the problem then is that access to transient is not done via AnnotationIntrospector but rather via direct check. So this may actually require an additional method in AnnotationIntrospector.

On the other hand, reading through the Javadocs, annotation can only be defined for methods, and it looks like intent is to indeed consider this ignoral marker.

So I'll go ahead and implement it that way.

[tmortagne]

So I'll go ahead and implement it that way.

Note: for what it worth that's what I did on my side for now so at least me will be happy :)

[cowtowncoder]

Ok good, so at least this will do what some of the users are using it for.
(in fact, everyone whose use cases I am familiar with :) )