Deserializing JSON into object with overloaded methods using Jackson

Question

I am attempting to deserialize a JSON object stored in CouchDb using Jackson. This object needs to deserialize into a pojo that contains overloaded methods. When I attempt to retrieve the object from couch and do the deserialization I get the following exception:

org.ektorp.DbAccessException: org.codehaus.jackson.map.JsonMappingException: Conflicting setter definitions for property "multiplier": com.db.commodities.framework.sdos.model.security.EqOpt#setMultiplier(1 params) vs com.db.commodities.framework.sdos.model.security.EqOpt#setMultiplier(1 params)

I tried to annotate the setter I would like Jackson to use, but that appears to not have worked.

@JsonProperty("multiplier") public void setMultiplier(SDOSAttribute multiplier) {      this.multiplier = multiplier; }  public void setMultiplier(double multiplier) {      this.multiplier.setValue(String.valueOf(multiplier)); } 

How do I configure Jackson to properly deserialize using a specific method? Or am I approaching this problem the wrong way?

EDIT:

I have made the following changes. This seems to work, but is a little uglier. If anyone has a better way to do this please feel free to share and I will gladly accept.

@JsonProperty("multiplier") protected void setMultiplierAttribute(SDOSAttribute multiplier) {     this.multiplier = multiplier; }  @JsonIgnore public void setMultiplier(double multiplier) {     this.multiplier.setValue(String.valueOf(multiplier)); } 

Answer 1

It's not necessary to change the name of the setter method to avoid ambiguity. You're otherwise on the right track with @JsonIgnore. With @JsonIgnore on all of the same-named methods to be ignored, the one to use does not need the @JsonProperty annotation.

Here's a simple example to demonstrate this point.

input.json: {"value":"forty-two"}

Foo.java:

import java.io.File;  import org.codehaus.jackson.annotate.JsonIgnore; import org.codehaus.jackson.map.ObjectMapper;  public class Foo {   String value;    public String getValue() {return value;}   public void setValue(String value) {this.value = value;}    @JsonIgnore   public void setValue(int value) {this.value = String.valueOf(value);}    public static void main(String[] args) throws Exception   {     ObjectMapper mapper = new ObjectMapper();     Foo foo = mapper.readValue(new File("input.json"), Foo.class);     System.out.println(mapper.writeValueAsString(foo));   } } 

If you don't want to alter the pristine POJO defs with a Jackson annotation, then you can use a MixIn.

import java.io.File;  import org.codehaus.jackson.annotate.JsonIgnore; import org.codehaus.jackson.map.ObjectMapper;  public class Foo {   String value;    public String getValue() {return value;}   public void setValue(String value) {this.value = value;}   public void setValue(int value) {this.value = String.valueOf(value);}    public static void main(String[] args) throws Exception   {     ObjectMapper mapper = new ObjectMapper();     mapper.getDeserializationConfig().addMixInAnnotations(Foo.class, IgnoreFooSetValueIntMixIn.class);     Foo foo = mapper.readValue(new File("input.json"), Foo.class);     System.out.println(mapper.writeValueAsString(foo));   } }  abstract class IgnoreFooSetValueIntMixIn {   @JsonIgnore public abstract void setValue(int value); } 

Answer 2

In Jackson > 2.4 use directly :

mapper.addMixIn(Foo.class, IgnoreFooSetValueIntMixIn.class);