First attribute of list ignored

[dewthefifth]

The unit test below will reproduce the problem. The general problem is that when the XML is deserialized jackson skips the attributes in the first entry of a list. All subsequent entries have their attributes read, and using an element instead of an attribute will work, but the first item in the list has it's attributes ignored.

I tried stepping through the code a bit, and found that the JsonParser tokens seem to go straight from the "wrapper" field to the "a" field without ever stopping at the "id" field. I could be wrong about this though.

import java.io.StringReader;
import java.util.List;

import junit.framework.Assert;

import org.junit.Test;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty;

public class TestParseMarketStat
{
    @Test
    public void testBrokenParser() throws Exception
    {
        String xml = "<response><wrapper><item id=\"1\"><a>x</a><b>y</b></item><item id=\"2\"><a>y</a><b>x</b></item></wrapper></response>";
        XmlMapper mapper = new XmlMapper();
        Response res = mapper.readValue(new StringReader(xml), Response.class);

        System.out.println(new ObjectMapper().writeValueAsString(res));
        Assert.assertNotNull(res.getItems().get(0).getId());
    }

    public static class Response
    {
        @JacksonXmlProperty(localName = "wrapper")
        List<Item> items;

        public List<Item> getItems()
        {
            return items;
        }

        public void setItems(List<Item> items)
        {
            this.items = items;
        }
    }

    public static class Item
    {
        protected String id;
        protected String a;
        protected String b;

        public String getId()
        {
            return id;
        }

        public void setId(String id)
        {
            this.id = id;
        }

        public String getA()
        {
            return a;
        }

        public void setA(String a)
        {
            this.a = a;
        }

        public String getB()
        {
            return b;
        }

        public void setB(String b)
        {
            this.b = b;
        }

    }
}

[cowtowncoder]

You are probably right, and I am guessing this behavior may be related to a fix made to allow mapping of special case, where String-value elements had "xml:lang" value (included in 2.1). It should obviously not lead to data loss as here, but perhaps does. Or it may be related to other aspects of optional wrapping of array values (and specifically case where there is no wrapping).

[cowtowncoder]

I can reproduce the issue; adding (failing) unit test. Interestingly, id of second item is handled appropriately, just not the first one.

[cowtowncoder]

Digging in deeper, problem only occurs if wrapper does not have attributes, but the first value has.
In this case, call to skipAttributes() occurs when pointing to the first value; whereas in the other case it still points to the wrapper element

[cowtowncoder]

Fixed for 2.2 -- fix itself is simple, so theoretically could backport to 2.1; however, since there could be regression (none of unit test fails, so there shouldn't be, but...), prefer fixing in new minor release.