Jersey loses id field

Question

I am using Jersey as JSR 311 implementation. The object i am trying to convert to JSON looks like this:

@XmlRootElement
public class deliveryTimes{
  private Integer id;
  private Short type;
  private Integer orderId;
  /* ... more fields and autogenerated Getters & Setters ... */
}

The JSON result is:

{"deliveryTimes":
[{"type":"1","orderId":"30449",/* ... other fields ... */ },
/* ... */
]}

In words: The field "id" is getting lost. In my other objects the id-fields have other names like orderId, customerId, ... and these fields don't get lost.

My pom.xml looks like this:

<!-- other stuff -->
<!--  JERSEY -->
<dependency>
    <groupId>com.sun.jersey</groupId>
    <artifactId>jersey-server</artifactId>
    <version>1.11</version>
</dependency>
<dependency>
    <groupId>com.sun.jersey</groupId>
    <artifactId>jersey-json</artifactId>
    <version>1.11</version>
</dependency>
<dependency>
    <groupId>com.sun.jersey</groupId>
    <artifactId>jersey-grizzly2</artifactId>
    <version>1.11</version>
</dependency>
<dependency>
    <groupId>com.sun.jersey</groupId>
    <artifactId>jersey-servlet</artifactId>
    <version>1.11</version>
</dependency>

<!-- Jersey + Spring -->
<dependency>
    <groupId>com.sun.jersey.contribs</groupId>
    <artifactId>jersey-spring</artifactId>
    <version>1.11</version>
    <exclusions>
        <exclusion>
            <groupId>org.springframework</groupId>
            <artifactId>spring</artifactId>
        </exclusion>
        <exclusion>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
        </exclusion>
        <exclusion>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
        </exclusion>
        <exclusion>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
        </exclusion>
        <exclusion>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<!-- other stuff -->

There's no further configuration. I didn't find anything helpful on the jersey website or via google, so I ended up here with my first post ever.

Is there any config option I am missing? How do you JSONify id-fields?

Answer 1

There are a number of reasons why the id may not be marshalled.

1 - It has a null value

By default JAXB implementations will not marshal out null values. If you wish to marshal out a null value be sure to add the following annotation

@XmlElement(nillable=true)

For More Information See:

• http://blog.bdoughan.com/2012/04/binding-to-json-xml-handling-null.html

2 - There is a field but not no accessor (get/set) methods

By default JAXB only maps public fields and accessors. Anything not matching this criteria is considered unmapped. You can solve this issue by specifying XmlAccessorType(XmlAccessType.FIELD)

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class deliveryTimes{
    ...
}

or by annotating the field

@XmlRootElement
public class deliveryTimes{
    @XmlElement
    private Integer id;
}

For More Information See:

• http://blog.bdoughan.com/2011/06/using-jaxbs-xmlaccessortype-to.html

3 - There is a get method but no set method

If there is a get method but no accompanying set method then your JAXB implementation will treat it as an unmapped property. To fix this you simply need to map the get method with @XmlElement.

Answer 2

There's nothing special about "id". From the @XmlRootElement on your class, I assume you're using JAXB for marshalling (the default with Jersey). In a default configuration, JAXB requires a getter to marshal a field to XML/JSON and a setter to unmarshal a field from XML/JSON. In this case, I'd guess you're lacking a public Integer getId() method. You can easily change this behavior by adding @XmlElement to your id field.