how to remove unnecessary xmlns="" in the child element

[eonezhang]

Hello guys,
I want to add namespace to the root element, but the child elements were attached an empty xmlns="", would you guys help me to remove the redundant bugs.

here is my xml output

<Parent xmlns="http://www.163.com/api/v1">
  <name xmlns="">parent</name>
  <Child xmlns="">
    <age>18</age>
  </Child>
</Parent>

I want to remove the xmlns="" in the <name xmlns="">parent</name> and <Child xmlns="">

here is my java code

package utils;

import java.io.IOException;

import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLOutputFactory;

import com.ctc.wstx.stax.WstxInputFactory;
import com.ctc.wstx.stax.WstxOutputFactory;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.dataformat.xml.XmlFactory;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlRootElement;

import lombok.Getter;
import lombok.Setter;
import lombok.experimental.Accessors;

/**
 * @author eonezhang (eonezhang@gmail.com)
 * @since 2019-08-13-18:30
 */
public class DemoTest {

    public static final String NS = "http://www.163.com/api/v1";

    public static void main(String[] args) throws IOException {
        DemoTest t = new DemoTest();
        t.marshallTest();
    }

    public void marshallTest() throws IOException {
        Parent p = new Parent()
              .setChild(new Child().setAge(18))
              .setName("parent");

        mashall(p);
    }

    private void mashall(Parent p) throws IOException {

        XMLInputFactory ifactory = new WstxInputFactory();
        XMLOutputFactory ofactory = new WstxOutputFactory();
        XmlFactory xf = new XmlFactory(ifactory, ofactory);

        ObjectMapper xmlMapper = new XmlMapper(xf);
        xmlMapper.enable(SerializationFeature.INDENT_OUTPUT);

        xmlMapper.writeValue(System.out, p);
    }

    @Getter
    @Setter
    @Accessors(chain = true)
    @JacksonXmlRootElement(localName = "Parent", namespace = NS)
    public static class Parent {
        @JacksonXmlProperty(localName = "Child")
        private Child child;
        private String name;
    }

    @Getter
    @Setter
    @Accessors(chain = true)
    public static class Child {
        private Integer age;
    }
}

and here is my dependencies

implementation 'com.fasterxml.jackson.dataformat:jackson-dataformat-xml:2.9.9'
implementation 'com.fasterxml.jackson.module:jackson-module-jaxb-annotations:2.9.9'
implementation 'com.fasterxml.woodstox:woodstox-core:5.3.0'
    

[cowtowncoder]

That is not a bug but feature. Your Parent has namespace with non-empty URI; Child on the other hand does not, and needs "empty" namespace. That must be declared (with @JacksonXmlProperty which has property for specifying namespace, similar to @JacksonXmlRootElement).

Or, you need to declare same namespace for Child and (I think) name.

[jawpio]

The feature is quite poor IMO, as you must annotate actually EACH field with JacksonXmlProperty with the same namespace.

[simon04]

Relates to #18.