Jackson Object mapper how to Serialize object as String which is having nested object? - jackson-databind

Question

I have json like following
{"data": [
{
"instance": { ...
"inner"" {....
.............}
}
}]
"isvalid":true
"nextVal" : <some num>
}
and POJO like
class A{
private String data;
private boolean isvalid;
private String nextVal;
//with getter setters and proper jackson annotations
}
These can have variable structure inside data, so with object mapper.read I want to take entire data object in string!
have tried direct serialization to my simple object which obviously gives error and also tried JSONNode
mapper.readValue(jsonString, JsonNode.class);
String content = node.get("data").textValue();
This returns blank
anyway I can achieve that to take entire data object value in string with objectmapper?

Answer 1

I tried toString and returned just fine what I wanted - entire data object as String
JsonNode node = (ObjectNode) mapper.readValue(jsonString, JsonNode.class);
node.get("data").toString();

Answer 2

The reason it returns blank is because, data is an array. You need to deseralise it in to JsonArray. Assuming your JSON structure as below,
{
"data": [
{"instance": {
"inner": {
"id": "1"
}
}
}],
"isvalid": true,
"nextVal": 1
}
This will be deserialised using below code (in JSONNode),
List<JsonNode> list = node.findValues("data");
for(JsonNode n: list){
JsonNode in1 = n.findValue("instance");
JsonNode in2 = in1.findValue("inner");
String abc = in2.findValue("id").textValue();
System.out.println(abc);
}
You need to have the POJO structure as shown above. The data will be list of instance object. instance object will have to have inner object.
Update:
Outer node = mapper.readValue(jsonstr, Outer.class);
The classes which needs to be created would be as shown below.
public class Outer {
private List<Data> data;
Boolean valid;
Integer nextval;
public List<Data> getData() {
return data;
}
public void setData(List<Data> data) {
this.data = data;
}
public Boolean isValid() {
return valid;
}
public void setValid(Boolean valid) {
this.valid = valid;
}
public Integer getNextval() {
return nextval;
}
public void setNextval(Integer nextval) {
this.nextval = nextval;
}
}
public class Data {
Instance instance;
public Instance getInstance() {
return instance;
}
public void setInstance(Instance instance) {
this.instance = instance;
}
}
public class Instance {
private Inner inner;
public Inner getInner() {
return inner;
}
public void setInner(Inner inner) {
this.inner = inner;
}
}
public class Inner {
private String id;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
}