jackson - jackson not creating json for nested objects

Question

I have a user list class and an API that returns user list and total records. The class is as follows :

@JsonInclude(JsonInclude.Include.NON_NULL)
public class FMSResponseInfo {

    @JsonProperty("status")
    private String status;
    @JsonProperty("message")
    private String message;
    @JsonProperty("data")
    private Object data;

    @JsonProperty("status")
    public String getStatus() {
        return status;
    }

    @JsonProperty("status")
    public void setStatus(String status) {
        this.status = status;
    }

    @JsonProperty("message")
    public String getMessage() {
        return message;
    }

    @JsonProperty("message")
    public void setMessage(String message) {
        this.message = message;
    }

    @JsonProperty("data")
    public Object getData() {
        return data;
    }

    @JsonProperty("data")
    public void setData(Object data) {
        this.data = data;
    }
}

@JsonInclude(JsonInclude.Include.NON_NULL)
public class UserListResDTO {

    @JsonProperty("users")
    private List<UserDTO> users;
    @JsonProperty("totalRecords")
    private long totalRecords;

    public List<UserDTO> getUsers() {
        return users;
    }
    public void setUsers(List<UserDTO> users) {
        this.users = users;
    }
    public long getTotalRecords() {
        return totalRecords;
    }
    public void setTotalRecords(long totalRecords) {
        this.totalRecords = totalRecords;
    }
}

I am setting an object of type UserListResDTO in FMSResponseInfo as shown below.

I have been successful in creating web services and returning response as json, so far. But the problem I am facing is that the API returns the response as follows : {"data":"org.package.UserListResDTO@70783307","message":"Success","status":"200"}

And this is how I have written the web service :

    @Path("/getUsers")
    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public FMSResponseInfo getUsers(@QueryParam("page") @DefaultValue("0") int page) {
        System.out.println("In getUsers()");
        FMSResponseInfo fmsResponseInfo = new FMSResponseInfo();
        try {
            UserListResDTO userList = fmsUserManager.getAllUsers(page);
            fmsResponseInfo.setData(userList);
            fmsResponseInfo.setStatus(FMSErrorMessageEnum.SUCCESS_CODE.getValue());
            fmsResponseInfo.setMessage(FMSErrorMessageEnum.SUCCESS_MESSAGE.getValue());
        } catch (Exception e) {
            return FMSUtil.getErrorResponseInfo(FMSErrorMessageEnum.INTERNAL_SERVER_ERROR_CODE.getValue(),
                    e.getMessage());
        }
        System.out.println("Out getUsers()");
        return fmsResponseInfo;
    }

I guess there is some problem with the dependencies or something that I am unable to resolve. Major dependencies in my pom are :

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.containers</groupId>
            <artifactId>jersey-container-servlet</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.7.2</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.7.2</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.media</groupId>
            <artifactId>jersey-media-moxy</artifactId>
        </dependency>

and I am creating Web services by extending Application class as follow :

@ApplicationPath("rest")
public class FMSApplication extends Application {    
    public Set<Class<?>> getClasses(){
        Set<Class<?>> set = new HashSet<Class<?>>();
        set.add(FMSUserManagerWebService.class);
        set.add(FMSDocumentManagerWebService.class);
        set.add(FMSInboxManagerWebService.class);
        set.add(FMSLocationManagerWebService.class);
        return set;
    }       
}

Any help will be really appreciated as I am new to this REST web services and have been stuck for quite long.

Answer 1

This link will explain the answer

https://jersey.java.net/documentation/latest/media.html#d0e7963

9.1.1.1. POJO support

POJO support represents the easiest way to convert your Java Objects to JSON and back.

Media modules that support this approach are MOXy and Jackson

The link to Jackson includes

9.1.4.1. Dependency

To use Jackson 2.x as your JSON provider you need to add jersey-media-json-jackson module to your pom.xml file

<dependency>
    <groupId>org.glassfish.jersey.media</groupId>
    <artifactId>jersey-media-json-jackson</artifactId>
    <version>2.22.2</version>  
</dependency>

I don't know much about moxy but you had jackson on your CLASSPATH and were using Jackson annonations. Jersey however was configured to use moxy.

From link

JSON binding support via MOXy is a default and preferred way of supporting JSON binding in your Jersey applications since Jersey 2.0. When JSON MOXy module is on the class-path, Jersey will automatically discover the module and seamlessly enable JSON binding support via MOXy in your applications.

MOXy seemed to have handled FMSResponseInfo. Why it didn't handle the other object I do not know. But since you wanted to use Jackson you should have been using the Jackson module.

Answer 2

As suggested by Shire Resident in the comments using the following dependency I was able to resolve the problem :

<dependency> 
  <groupId>org.glassfish.jersey.media</groupId> 
  <artifactId>jersey-media-json-jackson</artifactId> 
  <version>2.22.2</version> 
</dependency>