How to unwrap and serialize java map in java using jackson?

Question

I have a bean like this

class Foo {
    private Map<String, Data> dataMap;
    private String fooFieldOne;
    private String fooFieldTwo;
}

class Data {
    private fieldOne;
    private fieldTwo;
}

I want to serialize as Json as like this

{
    "key1": {
        "fieldOne": "some value",
        "fieldTwo": "some value"
    },
    "key2": {
        "fieldOne": "some other value",
        "fieldTwo": "some other value"
    },
    "fooFieldOne":"valueone", 
    "fooFieldTwo":"valuetwo" 
}

But i am getting result like

{
    "dataMap": {
        "key1": {
            "fieldOne": "some value",
            "fieldTwo": "some value"
        },
        "key2": {
            "fieldOne": "some other value",
            "fieldTwo": "some other value"
        }
    },
    "fooFieldOne":"valueone", 
    "fooFieldTwo":"valuetwo" 
}

How to ignore dataMap layer in the above json? I'm using java jackson library for this.

Code i tried is

ObjectMapper mapper = new ObjectMapper();
mapper.writeValueAsString(myFOOObject)

Answer 1

You could create a getter for dataMap and serialize the dataMap instead of the entire Foo instance.

mapper.writeValueAsString(myFOOObject.getDataMap());

Another method is using the @JsonUnwrapped annotation. This annotation is available in Jackson 1.9+.

http://jackson.codehaus.org/1.9.9/javadoc/org/codehaus/jackson/annotate/JsonUnwrapped.html

The downside of using this annotation is the inability to use maps as stated in the answer to your other question

Answer 2

I found answer - using @JsonAnyGetter annotation with getter for map. To avoid conflicts during deserialization should be used @JsonAnySetter annotation with setter for this map.