How to map a nested value to a property using Jackson annotations?

How to map a nested value to a property using Jackson annotations?

To map a nested value to a property using Jackson annotations in Java, you can use the @JsonProperty annotation along with dot notation to specify the path to the nested value. Here's how you can do it:

Suppose you have a JSON object with a nested structure like this:

{
    "person": {
        "name": "John",
        "age": 30
    }
}

And you want to map the "name" field within the "person" object to a property in your Java class.

Here's how you can achieve this using Jackson annotations:

import com.fasterxml.jackson.annotation.JsonProperty;

public class MyObject {
    @JsonProperty("person.name")
    private String personName;

    // Getter and setter for personName

    @Override
    public String toString() {
        return "MyObject{" +
                "personName='" + personName + '\'' +
                '}';
    }
}

In this example:

  • We annotate the personName field with @JsonProperty("person.name") to specify that it should be mapped to the "name" field within the "person" object in the JSON.

  • Jackson will use dot notation to navigate the JSON structure and map the nested "name" field to the personName property.

  • You can then use Jackson's ObjectMapper to deserialize the JSON into a MyObject instance:

import com.fasterxml.jackson.databind.ObjectMapper;

public class Main {
    public static void main(String[] args) throws Exception {
        String json = "{\"person\":{\"name\":\"John\",\"age\":30}}";
        
        ObjectMapper objectMapper = new ObjectMapper();
        MyObject myObject = objectMapper.readValue(json, MyObject.class);
        
        System.out.println(myObject);
    }
}

When you run this code, Jackson will map the nested "name" field to the personName property, and you'll get the following output:

MyObject{personName='John'}

This allows you to map nested values from a JSON object to properties in your Java class using Jackson's @JsonProperty annotation with dot notation.

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