Re: [Simple-support] erialize/deserialize Lists with empty Strings

[<Nia...@ub...>]

Hi, 

Yes this is true. And here is why the empty string is a bit of a special
case. In XML the following two structures are equal, daft but true.

<string></string>

And 

</string>

So how do you write an empty string as an element, versus null? Well for
@Attribute and @Text you will notice I have an empty() attribute for the
annotation so that if I were to write null I could have some form of
replacement like so.

@Attribute(empty="NULL")
private String field = null;

This would be written like so:

field="NULL"

So that deserialization knows to substitute "NULL" the string value with
a null. For elements its not as easy, perhaps there should be a similar
attribute for the @ElementList annotation. But for now, I am afraid the
empty string needs to be differentiated from null by some means. Usually
its best to use an @Persist and @Complete to replace "" values with
something so that they can be converted back to "" when read in again
using an @Commit method callback. Hope this helps.

Niall

 

-----Original Message-----
From: Joe [mailto:fis...@ya...] 
Sent: 16 December 2008 13:56
To: sim...@li...
Subject: [Simple-support] erialize/deserialize Lists with empty Strings

Hi,

The following code prints:
values: [A, null]

Why null and not an empty String?

How can serialize/deserialize Lists with empty Strings?

thx


public class TestData
{
    @ElementList(name = "values", required = false)
    private List<String> _values = new ArrayList<String>();

    TestData()
    {
        _values.add("A");
        _values.add("");
    }

    List<String> getValues()
    {
        return _values;
    }

    public static void main(String[] args) throws Exception
    {
        Serializer serializer = new Persister();
        File xmlFile = new File("test.xml");
        serializer.write(new TestData(), xmlFile);
       
        TestData sqlData = serializer.read(TestData.class, xmlFile);
        System.out.println("values: " + sqlData.getValues());
    }
}


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