Jersey/Jackson @JsonIgnore on setter

Question

i have an class with the following annotations:

class A {
public Map<String,List<String>> references;

@JsonProperty
public Map<String,List<String>> getReferences() {
...
}

@JsonIgnore
public void setReferences(Map<String,List<String>>) {
}
...
}
}

What I try is to ignore the json on deserialization. But it doesn't work. Always when JSON String arrives the Jackson lib fill the references attribute. If I use only the @JsonIgnore annotation the getter doesn't work. Are there any solutions for this problem?

Thanks

Solution 1

I think there are two key pieces that should enable you to have "read-only collections" as desired. First, in addition to ignoring the setter, ensure that your field is also marked with @JsonIgnore:

class A {

  @JsonIgnore
  public Map<String,List<String>> references;

  @JsonProperty
  public Map<String,List<String>> getReferences() { ... }

  @JsonIgnore
  public void setReferences(Map<String,List<String>>) { ... }

}

Second, in order to prevent the getters from being used as setters, disable the USE_GETTERS_AS_SETTERS feature:

ObjectMapper mapper = new ObjectMapper();
mapper.disable(MapperFeature.USE_GETTERS_AS_SETTERS);

Solution 2

As of Jackson 2.6, there is a new and improved way to define read-only and write-only properties, using JsonProperty#access() annotation. This is recommended over use of separate JsonIgnore and JsonProperty annotations.

@JsonProperty(access = JsonProperty.Access.READ_ONLY)
public Map<String,List<String>> references;

Solution 3

You have to make sure there is @JsonIgnore annotation on the field level as well as on the setter, and getter annotated with @JsonProperty.

public class Echo {

    @Null
    @JsonIgnore
    private String doNotDeserialise;

    private String echo;

    @JsonProperty
    public String getDoNotDeserialise() {
        return doNotDeserialise;
    }

    @JsonIgnore
    public void setDoNotDeserialise(String doNotDeserialise) {
        this.doNotDeserialise = doNotDeserialise;
    }

    public String getEcho() {
        return echo;
    }

    public void setEcho(String echo) {
        this.echo = echo;
    }
}

@Controller
public class EchoController {

@ResponseBody
@RequestMapping(value = "/echo", consumes = APPLICATION_JSON_VALUE, produces = APPLICATION_JSON_VALUE)
    public Echo echo(@RequestBody @Valid Echo echo) {
        if (StringUtils.isEmpty(echo.getDoNotDeserialise())) {
            echo.setDoNotDeserialise("Value is set by the server, not by the client!");
        }

        return echo;
    }
}

• If you submit a JSON request with a “doNotDeserialise” value set to something, when JSON is deserialised to an object it will be set to null (if not I put a validation constraint on the field so it will error out)
• If you set the “doNotDeserialise” value to something on the server then it will be correctly serialised to JSON and pushed to the client

Solution 4

I used @JsonIgnore on my getter and it didn't work and I couldn't configure the mapper (I was using Jackson Jaxrs providers). This worked for me:

@JsonIgnoreProperties(ignoreUnknown = true, value = { "actorsAsString",
    "writersAsString", "directorsAsString", "genresAsString" }) 

View more solutions

Comments

[guerilla]

That's right. The incoming data is not really in our hands. But the clients sends always references attribute in correct format so handleUnknown will never be called.

[Pete]

Ah, my bad, forgot a little pice of information. You need @JsonIgnoreProperties at the POJO if you want to ignore incoming data. I'll update my post. (PS: we use this to consume facebook's REST resource and all properties sent from facebook that are not contained in our POJO will just get logged and then we decide if we want to add them or not)

[guerilla]

But references is in my POJO so it always matches to the setter

[Pete]

But why do you keep References in your POJO if you don't need it? Found another solution that might be applicable if you really want to keep your exact structure: stackoverflow.com/questions/7421474/…

[guerilla]

Thanks for the link. I've tried mixins before and it works not for me. The challenge is getting the references property to Read-only state. So that I can send information to the client but ignore incoming changes on this property