json parsing with jackson

Question

I am using the Jackson library for conversion of a JSON string to Java objects

My json is:

{ 
 "human":{ 
 "fname":"anjali",
 "lname":"malhotra"
 }
}

I want this to be converted into a Java class with following structure:

public class Human
{
 String fname;
 String lname;
}

I can successfully convert it into

public class HumanWrapper
{
 Human human;
}

But, I wanted to know if there is a way I can directly convert it into the Human format. I read about custom deserialization but was reluctant for that approach.

• Michał Ziober: You can use DeserializationFeature.UNWRAP_ROOT_VALUE feature. Examples you can find here: JSON Jackson deserialization multiple keys into same field, Jackson - deserialize inner list of objects to list of one higher level, Mapping Json string to map or hashmap field in java

Answer 1

You could achieve this by configuring ObjectMapper to use DeserializationFeature.UNWRAP_ROOT_VALUE :

ObjectMapper mapper = new ObjectMapper();
mapper.configure(DeserializationFeature.UNWRAP_ROOT_VALUE, true);

and annotatating your Human class with @JsonRootName annotation :

@JsonRootName("human")
public class Human {
....
}

• Nikita Shah: Thanks.. I will try this out and update the result.
• Nikita Shah: Related question:- stackoverflow.com/questions/60950529/…

Answer 2

You need to have a HumanWrapper class as your human object is defined inside you json object

{
 "human": {
 }
}

If you able to change you API to send just a human object like this

{ 
 "fname":"anjali",
 "lname":"malhotra"
}

Then you woudn't be bothering to have a HumanWrapper

• Nikita Shah: In the current framework in my Organization, changing the API response is not possible. And I felt that adding a wrapper just for this is maybe not the best approach