Re: [Simple-support] How to handle an empty XML element, when using a Converter via "@Convert"

[Timo R. <tim...@di...>]

Hello Niall,

> Looks like a bug to me, ill take a closer look at it. If it's a bug ill
release a fix for it shortly.
> Sounds like a good idea

any progress on this? It would be really helpful in my current project. It
would be great if a "Converter" is allowed to return null (or a "Value"
instance with its "value" property to be null).


Thanks a lot!


Best Regards,
Timo



-----Ursprüngliche Nachricht-----
Von: Niall Gallagher [mailto:gal...@ya...] 
Gesendet: Mittwoch, 27. Februar 2013 11:21
An: sim...@li...; Timo Rumland
Betreff: Re: [Simple-support] How to handle an empty XML element, when using
a Converter via "@Convert"

Sounds like a good idea

--- On Tue, 26/2/13, Timo Rumland <tim...@di...> wrote:

> From: Timo Rumland <tim...@di...>
> Subject: Re: [Simple-support] How to handle an empty XML element, when
using a Converter via "@Convert"
> To: sim...@li...
> Received: Tuesday, 26 February, 2013, 11:43 PM Hello Niall,
> 
> > Looks like a bug to me, ill take a closer look at it.
> If it's a bug ill
> release a fix for it shortly.
> 
> thanks a lot for your answer!
> 
> Now in my opinion, a Converter should be allowed to return null (or a 
> "Value" instance with its "value" property to be null).
> 
> I could imagine, that there are circumstances, where a special value 
> in a XML tag must be converted to "null" in the target/deserialized 
> object. So allowing a converter to convert to null would enhance the 
> flexibility (you could write a converter which converts 
> <time>null</null> to Java's 'null' in the deserialized object).
> 
> 
> Best Regards,
> Timo
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: Niall Gallagher - Yieldbroker 
> [mailto:Nia...@yi...]
> 
> Gesendet: Dienstag, 26. Februar 2013 23:21
> An: Timo Rumland; sim...@li...
> Betreff: RE: [Simple-support] How to handle an empty XML element, when 
> using a Converter via "@Convert"
> 
> Looks like a bug to me, ill take a closer look at it. If it's a bug 
> ill release a fix for it shortly.
> 
> -----Original Message-----
> From: Timo Rumland [mailto:tim...@di...]
> 
> Sent: Wednesday, 27 February 2013 4:42 AM
> To: sim...@li...
> Subject: [Simple-support] How to handle an empty XML element, when 
> using a Converter via "@Convert"
> 
> Hello,
> 
> I have the following situation: I'm using the @Convert annotation with 
> my own converter implementation on a class field named "time".
> 
> When I now try to deserialize XML, which contains that "time" element 
> but is empty like this:
> 
> ----
> <time></time>
> ----
> 
> my converter will be called and the SimpleXML framework throws an 
> exception:
> 
> ----
> [...]
> Caused by: java.lang.NullPointerException  at
> org.simpleframework.xml.convert.Reference.getType(Reference.java:70)
> ----
> 
> This is because my Converter implementation returns "null", when the 
> XML element is empty. As the javadoc for "Converter.read" tells, it is 
> not allowed to return "null".
> 
> But now my question is, how should I handle the situation, where I use 
> a Converter which is "confronted" with an empty XML element?
> 
> Looking at the Method
> 
>  
> "org.simpleframework.xml.convert.AnnotationStrategy.read(Type,
> NodeMap<InputNode>, Value)"
> 
> We can see the following code snipped:
> 
> ----
> if(converter != null) {
>   Object data = converter.read(parent);
>          
>   if(value != null) {
>     value.setValue(data);
>   }
>   return new Reference(value, data);
> }
> ----
> 
> This means, that if there is a @Converter defined, it gets called in 
> any case, even if the value of that XML element is empty/null.
> But at the same
> time, Converter.read(...) should not return "null".
> 
> I think the "AnnotationStrategy" class should handle this situation, 
> checking for an empty XML element, so the converter gets not called in 
> that case.
> 
> 
> So, what is the correct way to handle such a situation, or is it a 
> "drawback" (maybe even a bug) of the "AnnotationStrategy"
> class?
> 
> 
> Thanks a lot for your help!
> 
> 
> Best Regards,
> Timo
> 
> 
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