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

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Let's say I'm making a call to an API that responds with the following JSON for a product:

{
  "id": 123,
  "name": "The Best Product",
  "brand": {
     "id": 234,
     "name": "ACME Products"
  }
}

I'm able to map the product id and name just fine using Jackson annotations:

public class ProductTest {
    private int productId;
    private String productName, brandName;

    @JsonProperty("id")
    public int getProductId() {
        return productId;
    }

    public void setProductId(int productId) {
        this.productId = productId;
    }

    @JsonProperty("name")
    public String getProductName() {
        return productName;
    }

    public void setProductName(String productName) {
        this.productName = productName;
    }

    public String getBrandName() {
        return brandName;
    }

    public void setBrandName(String brandName) {
        this.brandName = brandName;
    }
}

And then using the fromJson method to create the product:

  JsonNode apiResponse = api.getResponse();
  Product product = Json.fromJson(apiResponse, Product.class);

But now I'm trying to figure out how to grab the brand name, which is a nested property. I was hoping that something like this would work:

    @JsonProperty("brand.name")
    public String getBrandName() {
        return brandName;
    }

But of course it didn't. Is there an easy way to accomplish what I want using annotations?

The actual JSON response I'm trying to parse is very complex, and I don't want to have to create an entire new class for every sub-node, even though I only need a single field.


You can achieve this like that:

String brandName;

@JsonProperty("brand")
private void unpackNameFromNestedObject(Map<String, String> brand) {
    brandName = brand.get("name");
}

How to map a nested value to a property using Jackson annotations , You can achieve this like that: String brandName; @JsonProperty("brand") private void unpackNameFromNestedObject(Map<String, String> brand)  Looking for what is the value of my property? Search now! eTour.com is the newest place to search, delivering top results from across the web.


This is how I handled this problem:

Brand class:

package org.answer.entity;

public class Brand {

    private Long id;

    private String name;

    public Brand() {

    }

    //accessors and mutators
}

Product class:

package org.answer.entity;

import com.fasterxml.jackson.annotation.JsonGetter;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonSetter;

public class Product {

    private Long id;

    private String name;

    @JsonIgnore
    private Brand brand;

    private String brandName;

    public Product(){}

    @JsonGetter("brandName")
    protected String getBrandName() {
        if (brand != null)
            brandName = brand.getName();
        return brandName;
    }

    @JsonSetter("brandName")
    protected void setBrandName(String brandName) {
        if (brandName != null) {
            brand = new Brand();
            brand.setName(brandName);
        }
        this.brandName = brandName;
    }

//other accessors and mutators
}

Here, the brand instance will be ignored by Jackson during serialization and deserialization, since it is annotated with @JsonIgnore.

Jackson will use the method annotated with @JsonGetter for serialization of java object into JSON format. So, the brandName is set with brand.getName().

Similarly, Jackson will use the method annotated with @JsonSetter for deserialization of JSON format into java object. In this scenario, you will have to instantiate the brand object yourself and set its name property from brandName.

You can use @Transient persistence annotation with brandName, if you want it to be ignored by persistence provider.

FasterXML/jackson Tips for JSON in Java - The Startup, Q3: How to deserialize nested JSON objects? Q4: How to So, we should map this JSON to a Java object that has the same fields. All fields are This will provide you some options such as changing the property name on  Jackson will use the method annotated with @JsonGetter for serialization of java object into JSON format. So, the brandName is set with brand.getName(). Similarly, Jackson will use the method annotated with @JsonSetter for deserialization of JSON format into java object.


You can use JsonPath-expressions to map nested properties. I don't think there's any official support (see this issue), but there's an unofficial implementation here: https://github.com/elasticpath/json-unmarshaller

How to access the JSON fields, arrays and nested objects of , We can return a valid string representation using the asText() method and convert the value of the node to a Java int using the asInt() method of  To map the nested brandName property, we first need to unpack the nested brand object to a Map and extract the name property. Then to map ownerName, we unpack the nested owner object to a Map and extract its name property. We can instruct Jackson to unpack the nested property by using a combination of @JsonProperty and some custom logic that we


The best is to use setter methods:

JSON:

...
 "coordinates": {
               "lat": 34.018721,
               "lng": -118.489090
             }
...

setter method for lat or lng will look like:

 @JsonProperty("coordinates")
    public void setLng(Map<String, String> coordinates) {
        this.lng = (Float.parseFloat(coordinates.get("lng")));
 }

if you need to read both (as you normally would do) then use a custom method

@JsonProperty("coordinates")
public void setLatLng(Map<String, String> coordinates){
    this.lat = (Float.parseFloat(coordinates.get("lat")));
    this.lng = (Float.parseFloat(coordinates.get("lng")));
}

Jackson Annotations for JSON (Part 3): Deserialization, Use this annotation when your JSON property names are different to the fields of the Java object class, and you want to map them. A Java class  This tutorial has been a deep-dive into Jackson annotations, just scratching the surface of the kind of flexibility you can get using them correctly. The implementation of all these examples and code snippets can be found in the GitHub project – this is a Maven-based project, so it should be easy to import and run as it is.


To make it simple ..I have written the code ...most of it is self explanatory.

Main Method

package com.test;

import java.io.IOException;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class LOGIC {

    public static void main(String[] args) throws JsonParseException, JsonMappingException, IOException {

        ObjectMapper objectMapper = new ObjectMapper();
        String DATA = "{\r\n" + 
                "  \"id\": 123,\r\n" + 
                "  \"name\": \"The Best Product\",\r\n" + 
                "  \"brand\": {\r\n" + 
                "     \"id\": 234,\r\n" + 
                "     \"name\": \"ACME Products\"\r\n" + 
                "  }\r\n" + 
                "}";

        ProductTest productTest = objectMapper.readValue(DATA, ProductTest.class);
        System.out.println(productTest.toString());

    }

}

Class ProductTest

package com.test;

import com.fasterxml.jackson.annotation.JsonProperty;

public class ProductTest {

    private int productId;
    private String productName;
    private BrandName brandName;

    @JsonProperty("id")
    public int getProductId() {
        return productId;
    }
    public void setProductId(int productId) {
        this.productId = productId;
    }

    @JsonProperty("name")
    public String getProductName() {
        return productName;
    }
    public void setProductName(String productName) {
        this.productName = productName;
    }

    @JsonProperty("brand")
    public BrandName getBrandName() {
        return brandName;
    }
    public void setBrandName(BrandName brandName) {
        this.brandName = brandName;
    }

    @Override
    public String toString() {
        return "ProductTest [productId=" + productId + ", productName=" + productName + ", brandName=" + brandName
                + "]";
    }



}

Class BrandName

package com.test;

public class BrandName {

    private Integer id;
    private String name;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return "BrandName [id=" + id + ", name=" + name + "]";
    }




}

OUTPUT

ProductTest [productId=123, productName=The Best Product, brandName=BrandName [id=234, name=ACME Products]]

Guide to Jackson Annotations, The annotation @JsonProperty is used to change the JSON property name used in InvalidFormatException: Can not deserialize value of type java.util. stored in a Map and these properties need to be exposed to JSON. How to map a nested value to a property using Jackson annotations? (4) Hi here is the complete working code.


Java and JSON – Jackson Serialization with ObjectMapper, Jackson serializes a Map as a JSON object whose keys are the keys' toString() set Maps as values if you want nested JSON objects, or you can use Java log.​info("Trying to deserialize with unknown properties" + " fails by  Clone via HTTPS Clone with Git or checkout with SVN using the repository’s web address.


Nested json object java example, We can create nested JSON file using java by using an external Lib :org Using dot notation the nested objects' property(car) is accessed This map object provides read-only access to the JSON object data, and attempts to modify the map,  We use Jackson's ObjectMapper as we did for serialization, using readValue() to process the input. Also, note our use of Jackson's TypeReference, which we'll use in all of our deserialization examples, to describe the type of our destination Map. Here is the toString() representation of our map: {key=value} 4.2. Map<Object, String> Deserialization


Jackson ObjectMapper, The Jackson ObjectMapper can read JSON into Java objects and write By default Jackson maps the fields of a JSON object to fields in a Java object by JSON string now contains an array field called owners and a nested  Hah, this is what I was thinking of, but didn't find it in the jackson-annotations javadocs (it's in jackson-databind). – vanza Oct 25 '13 at 16:50 The member type InnerItems cannot be declared static; static types can only be declared in static or top level types – coltonfranco Feb 6 '17 at 17:52