ACCEPT_EMPTY_STRING_AS_NULL_OBJECT not honored in xml module for attributes

[mortenoh]

I'm having some issues with the treatment of empty strings in the XML module.

Say I have this:

class A {
 @JacksonXmlProperty( isAttribute = true )
 private String stringA;
 private String stringB;
}

A a = new A();
a.setStringA("");
a.setStringB("");

In JSON this would give me:

{ "stringA": "", "stringB": ""}

In XML this gives me:

<A stringA="">
 <stringB />
</A>

Which means that the attribute is treated correctly (as according to
the defaults), but for the element, it shows up as null. And is
therefore deserialized back as a null string.

[cowtowncoder]

Hmmh. I don't quite follow: in XML is equivalent to ; there is no semantic difference.
I am also not sure iff ACCEPT_EMPTY_STRING_AS_NULL_OBJECT is relevant here, as it is just for deserialization (reading JSON/XML as POJO)...

So what is the problem, and how would you expect things to work instead?

[mortenoh]

Hi

I'm sorry I dont have access to my test project right now. But if I remember correctly, the issue was that, given the code:

class A {
 @JacksonXmlProperty( isAttribute = true )
 private String stringA = ""
 private String stringB = ""
}

This would give in XML (which I agree is correct):

<A stringA="">
 <stringB />
</A>

But, when deserialized, it would give me:

class A {
 @JacksonXmlProperty( isAttribute = true )
 private String stringA = ""
 private String stringB = null;
}

Hope this makes it a bit more clear. If you need more information, I will try and find my little test project for this.

[cowtowncoder]

Ah! Yes, this explains it better. Thank you -- unit tests are always appreciated, but I think I now understand the issue and can work on it.

[cowtowncoder]

Hmmh. ACCEPT_EMPTY_STRING_AS_NULL_OBJECT only states that empty String is a valid representation as null of any Object type, so behavior is not exactly incorrect.
But I can see it as sub-optimal. It probably works that way even without feature; I'll see if I can improve this as it would make sense to get empty String back. Chances are nothing gets set.

[cowtowncoder]

Since this is an old issue I am not sure if it can be reproduced as is. There are newer related issues as well, so I will close this one in favor of newer ones.

[ewirch]

Can you reference "newer related issues"? This problem is still present for 2.9.5.

[cowtowncoder]

Turns out there was a unit test I had added earlier. Was able to fix but only for 3.0.0, unfortunately, not 2.9.