Hi,
Villemos wrote:
>
> I'm new to XStream and XML to POJO conversion, so this problem is properly
> quite simple and stupid.
>
> I have the following XML string;
>
> <response>
> <status_code>0</status_code>
> <result>
> <item>
> <fieldset>General information</fieldset>
> <description>General document information</description>
> <fields>
> <item>
> <name>Document Author</name>
> <value>John Doe</value>
> </item>
> <item>
> <name>Reference ID</name>
> <value>OSMV-OPMT-LOGI-RP-11-1402</value>
> </item>
> </fields>
> </item>
> </result>
> </response>
>
>
> And have created the following classes;
>
> @XStreamAlias("response")
> public class Metadata {
>
> public String status_code = "";
>
> @XStreamAlias("result")
> public List<MetadataItem> result = new ArrayList<MetadataItem>();
This alias is superfluous, the field name is already "result".
> }
>
>
> @XStreamAlias("item")
> public class MetadataItem {
>
> public String fieldset = "";
> public String description = "";
>
> @XStreamAlias("fields")
> public List<MetadataField> fields = new ArrayList<MetadataField>();
> }
>
>
> @XStreamAlias("item")
> public class MetadataField {
As you found out, this does not work. You cannot assign the same alias to
different types. This has to be a 1:1 relation. With this definition, your
program behaves non-deterministic. Depending on the sequence of
registration, all "item" elements will be deserialized to Metadata or
MetadataField types.
> public String name = "";
> public String value = "";
> }
>
>
>
>
> Running the following junit tests fails misserably;
>
> public class MetadataTest extends TestCase {
>
> public void testConvert() {
> String testString = ...
>
> Metadata metadata = new Metadata();
> XStream xstream = new XStream();
> xstream.processAnnotations(MetadataField.class);
> xstream.processAnnotations(MetadataItem.class);
> xstream.processAnnotations(Metadata.class);
> xstream.fromXML(testString, metadata);
> }
> }
>
> The trace is shown below. I dont understand the error message; It looks
> like its in the MetadataField:name conversion that something goes wrong,
> but thats a String. How can a CannotResolveClassException be thrown?
>
>
>
> com.thoughtworks.xstream.converters.ConversionException: name : name :
> name
> : name
> ---- Debugging information ----
> message : name : name
> cause-exception :
> com.thoughtworks.xstream.mapper.CannotResolveClassException
> cause-message : name : name
> class : com.logica.oam.ktree.converters.Metadata
> required-type : com.logica.oam.ktree.converters.MetadataItem
> path : /response/result/item/fields/item/name
> line number : 1
> -------------------------------
It tries to create a Metadata instance, but that one has no field "name".
You should remove both item aliases and use local ListConverters where you
define that all elements are of the required type and should use the alias
'item' in the list. See the ListConverter constructor and
XStream.registerLocalConverter.
Cheers,
Jörg
---------------------------------------------------------------------
To unsubscribe from this list, please visit:
http://xircles.codehaus.org/manage_email
