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spring boot jackson generate dynamic property name with hierarchical levels

How to apply dynamic property name with counter in it.?
I am building a spring boot rest api that returns the following response object.
Response object is a structure with hierarchical levels. Instead of showing all the "levels" property name as default "levels", i want to dynamically put the level number to it as explained in the below sample json.
public class Root {
private String id;
private List<Level> levels;
}
public class Level {
private String name;
private List<Level> levels;
}
current json output:
{
"id" :"testid",
"levels" : [
{
"name" :"test1"
"levels" : [
{
"name": "test3"
"levels" : []
}
}
Sample expected json:
{
"id" :"testid",
"level1" : [
{
"name" :"test1"
"level2" : [
{
"name": "test3"
"level3" : []
}
}

i solved it as follows, by adding a field that contains current level and appending that to the field name.
public class Root {
private String id;
#JsonIgnore
private List<Level> levels;
#JsonIgnore
private int level;
#JsonAnyGetter
public Map<String, List<Level>> any() {
return Collections.singletonMap("level"+level, levels);
}
}
public class Level {
private String name;
private List<Level> levels;
#JsonIgnore
private int level;
#JsonAnyGetter
public Map<String, List<Level>> any() {
return Collections.singletonMap("level"+level, levels);
}
}

How to model JSON response with Jackson in Java?

I am try to model an Api response using Jackson. The id will be the same type in all but the body will be different types.
An example response would be:
{
"responses": [
{
"id": "jobTitle",
"body": {
"jobTitle": "Software Engineer"
}
},
{
"id": "thumbnailPhoto",
"body": "base 64 bit string"
}
]
}
I have the following implementation. Is this the correct approach? If the type for body returns as a string, would the JobTitle be ignored/ null?
#JsonIgnoreProperties(ignoreUnknown = true)
public class Response
{
#JsonProperty("id")
private String id;
#JsonProperty("body")
private String photo;
#JsonProperty("body")
private JobTitle jobTitle;
// getters and setters
}

I'm no expert in this area, but I would like to share my answer here.
I don't know why you design the JSON string as an array of responses for your original question. I would suggest a better design to be a single instance of "Response" object as below:
{
"id":"response id",
"jobTitle":"title",
"img":"img b64 string"
}
Just leave the field null if not exists.
But if you insist on using the origin design, below code below coding can be achieved, but the JSON string need small changes to add "type" info Tutorial from Baeldung.
[ {
"id" : "1",
"body" : {
"type" : "jobTitle",
"jobTitle" : "job title"
}
}, {
"id" : "2",
"body" : {
"type" : "img",
"data" : "xxxxx"
}
} ]
Java coding as below:
package org.example.test4;
import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import java.util.ArrayList;
public class TestApp {
public static class Response<X extends Body> {
private String id;
private X body;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public X getBody() {
return body;
}
public void setBody(X body) {
this.body = body;
}
}
#JsonTypeInfo(
use = JsonTypeInfo.Id.NAME,
include = JsonTypeInfo.As.PROPERTY,
property = "type"
)
#JsonSubTypes({
#JsonSubTypes.Type(value = JobTitle.class, name = "jobTitle"),
#JsonSubTypes.Type(value = IMG.class, name = "img")
})
public static abstract class Body{}
public static class JobTitle extends Body{
private String jobTitle;
public String getJobTitle() {
return jobTitle;
}
public void setJobTitle(String jobTitle) {
this.jobTitle = jobTitle;
}
}
public static class IMG extends Body{
private String data;
public String getData() {
return data;
}
public void setData(String data) {
this.data = data;
}
}
public static void main(String[] args) throws JsonProcessingException {
ObjectMapper om = new ObjectMapper().enable(SerializationFeature.INDENT_OUTPUT);;
JobTitle jt = new JobTitle();
jt.setJobTitle("job title");
System.out.println(om.writeValueAsString(jt));
IMG img = new IMG();
img.setData("xxxxx");
System.out.println(om.writeValueAsString(img));
ArrayList<Response<?>> rs = new ArrayList<Response<?>>();
Response<JobTitle> r1 = new Response<JobTitle>();
r1.setId("1");
r1.setBody(jt);
rs.add(r1);
Response<IMG> r2 = new Response<IMG>();
r2.setId("2");
r2.setBody(img);
rs.add(r2);
System.out.println(om.writeValueAsString(rs));
}
}

How to convert a POST API call with a JSON body to a java class in Springboot?

i'm passing a POST request with raw JSON body which holds the configuration details, i want to save it as a java class so i can distribute the data using getters to relevant classes that need the config details specified for them.This is the body of my request
{
"aisles" : 2,
"sections" : 2,
"shelves" : 1,
"packagingAreas": [ "a1.3", "a2.3" ],
"workers" : [
{
"name" : "rem",
"location" : "a1.1",
"capacity" : 20
}
],
"items" : [
{
"id" : "mars",
"name" : "Mars",
"supplier" : "Nestle",
"weight" : 1
},
{
"id" : "kitkat",
"name" : "Kit Kat",
"supplier" : "Nestle",
"weight" : 1
},
{
"id" : "dd",
"name" : "Double Decker",
"supplier" : "Nestle",
"weight" : 1
}
]
}
and i want to the details of that body into my config.java class, this is the config.java class
public class Config {
private static String aisles;
private static String sections;
private static String shelves;
private static String packagingAreas[];
private static ArrayList<Worker> workers;
private static ArrayList<Item> items;
public static String getAisles() {
return aisles;
}
public static String getSections() {
return sections;
}
public static String getShelves() {
return shelves;
}
public static String[] getPackagingAreas() {
return packagingAreas;
}
public static ArrayList<Worker> getWorkers() {
return workers;
}
public static ArrayList<Item> getItems() {
return items;
}
}
And i have modelled the worker and item classes with the same variables as in the json configuration file, is there a direct way to convert this JSON file to a class? if not what other methods can i try?
Thanks in advance!
edit- This is the endpoint i have created, using #Rest Controller
#RequestMapping(value ="/config", method = RequestMethod.POST)
public void configure() {
//i want to do the conversion here
}

Update the controller as follows
#RequestMapping(value ="/config", method = RequestMethod.POST)
public void configure(#RequestBody Config config) {
//your json is converted to config java object
}
Update your Config class
public class Config {
private String aisles;
private String sections;
private String shelves;
private String packagingAreas[];
private ArrayList<Worker> workers;
private ArrayList<Item> items;
public void setAisles(String aisles) {
this.aisles = aisles;
}
public void setSections(String sections) {
this.sections = sections;
}
public void setShelves(String shelves) {
this.shelves = shelves;
}
public void setPackagingAreas(String[] packagingAreas) {
this.packagingAreas = packagingAreas;
}
public void setWorkers(ArrayList<Worker> workers) {
this.workers = workers;
}
public void setItems(ArrayList<Item> items) {
this.items = items;
}
public String getAisles() {
return aisles;
}
public String getSections() {
return sections;
}
public String getShelves() {
return shelves;
}
public String[] getPackagingAreas() {
return packagingAreas;
}
public ArrayList<Worker> getWorkers() {
return workers;
}
public ArrayList<Item> getItems() {
return items;
}
}
Explanation
By default spring boot comes with several HttpMessageConverters enabled. One of them is MappingJacksonHttpMessageConverter which converts your json to java object.
See this http message converter

Order of JSON objects using Jackson's ObjectMapper

I'm using ObjectMapper to do my java-json mapping.
ObjectWriter ow = new ObjectMapper().writer().withDefaultPrettyPrinter();
ow.writeValue(new File( fileName +".json"), jsonObj);
this is my java class:
public class Relation {
private String id;
private String source;
private String target;
private String label;
private List<RelAttribute> attributes;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getSource() {
return source;
}
public void setSource(String source) {
this.source = source;
}
public String getTarget() {
return target;
}
public void setTarget(String target) {
this.target = target;
}
public String getLabel() {
return label;
}
public void setLabel(String label) {
this.label = label;
}
public void setAttributes(List<RelAttribute> attributes) {
this.attributes = attributes;
}
public List<RelAttribute> getAttributes() {
return attributes;
}
}
this is what I get:
{
"id" : "-75da69d3-79c8-4000-a3d8-b10350a57a7e",
"attributes" : [ {
"attrName" : "ID",
"attrValue" : ""
}, {
"attrName" : "Description",
"attrValue" : "Primary Actor"
}, {
"attrName" : "Status",
"attrValue" : ""
} ],
"label" : "new Label",
"target" : "-46b238ac-b8b3-4230-b32c-be9707f8b691",
"source" : "-daa34638-061a-45e0-9f2e-35afd6c271e0"
}
So my question now is, how can I get this json output:
{
"id" : "-75da69d3-79c8-4000-a3d8-b10350a57a7e",
"label" : "new Label",
"target" : "-46b238ac-b8b3-4230-b32c-be9707f8b691",
"source" : "-daa34638-061a-45e0-9f2e-35afd6c271e0",
"attributes" : [ {
"attrName" : "ID",
"attrValue" : ""
}, {
"attrName" : "Description",
"attrValue" : "Primary Actor"
}, {
"attrName" : "Status",
"attrValue" : ""
} ]
}
I want it with same order as in my java declaration. Is there a way to specify it ? Maybe with annotations or stuff like that ?

#JsonPropertyOrder({ "id", "label", "target", "source", "attributes" })
public class Relation { ... }

Do you know there is a convenient way to specify alphabetic ordering?
#JsonPropertyOrder(alphabetic = true)
public class Relation { ... }
If you have specific requirements, here how you configure custom ordering:
#JsonPropertyOrder({ "id", "label", "target", "source", "attributes" })
public class Relation { ... }

The ordering of fields within a generated .class is indeterminate, so you can't count on that.
If you want specific ordering per class then you'll need to use the one of the approaches specified in other answers.
If you want everything to default to alphabetical ordering (e.g. for consistency in how the JSON is structured) then you can configure the ObjectMapper like this:
ObjectMapper mapper = new ObjectMapper();
mapper.setConfig(mapper.getSerializationConfig()
.with(MapperFeature.SORT_PROPERTIES_ALPHABETICALLY));
For more consistent JSON consider also adding:
.with(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS)
One advantage of this approach is that you don't have to modify each class being serialized.

I discovered a third way today in case alphabetic is not your desired sorting order. It turns out adding a #JsonProperty annotation on a field places it last when writing. I discovered that when I wanted to specify a property name which did not conform to java naming conventions.
By Adding an index attribute you can define the order. Lowest index is placed first.
#JsonProperty(index=20)
String prop1;
#JsonProperty(index=10)
String prop2;
Would render:
{"prop2": "valueProp2", "prop1": "valueProp1"}

You can use #XmlAccessorType(XmlAccessType.FIELD)
#XmlType(name = "response", propOrder = { "prop1", "prop2",
"prop3", "prop4", "prop5", "prop6" }).
#JsonPropertyOrder requires a new jar to be added.

As per this documentation, you can configure Jackson2ObjectMapperBuilder globally. This class is available in spring-web dependency.
#Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
builder.featuresToEnable(MapperFeature.SORT_PROPERTIES_ALPHABETICALLY);
return builder;
}
Also, you can use #JsonProperty(index) to determine the order in inherited classes as well.
class animal {
#JsonProperty(index=2)
int p1;
#JsonProperty(index=3)
int p2;
}
class cat extends animal{
#JsonProperty(index=1)
int p3;
}

Json - Java Object to Json

I am very new to Json and my goal to create the Json output below from Java bean. How should I structure my Java object? Should I have MyResult class and User and Result as subclasses? What Json library can I use for this?
“MyResult” {
“AccountID”: “12345”,
"User" {
"Name": "blah blah",
"Email": “blah#blah.com”,
},
"Result" {
"Course": “blah”,
"Score": “10.0”
}
}

Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB (JSR-222) expert group.
How should I structure my Java object?
Below is what your object model could look like. MOXy's JSON binding leverages JAXB annotations for mapping the domain model to JSON, so I have included those as well. JAXB implementations have default rules for mapping field/property names, but since your document differs from the default each field had to be annotated.
MyResult
package forum11001458;
import javax.xml.bind.annotation.*;
#XmlRootElement(name="MyResult")
public class MyResult {
#XmlElement(name="AccountID")
private String accountID;
#XmlElement(name="User")
private User user;
#XmlElement(name="Result")
private Result result;
}
User
package forum11001458;
import javax.xml.bind.annotation.XmlElement;
public class User {
#XmlElement(name="Name")
private String name;
#XmlElement(name="Email")
private String email;
}
Result
package forum11001458;
import javax.xml.bind.annotation.XmlElement;
public class Result {
#XmlElement(name="Course")
private String course;
#XmlElement(name="Score")
private String score;
}
What Json library can I use for this?
Below is how you can use MOXy to do the JSON binding:
jaxb.properties
To use MOXy as your JAXB provider you need to include a file called jaxb.properties with the following entry in the same package as your domain model:
javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory
Demo
Note how MOXy's JSON binding does not require any compile time dependencies. All the necessary APIs are available in Java SE 6. You can add the necessary supporting APIs if you are using Java SE 5.
package forum11001458;
import java.io.File;
import javax.xml.bind.*;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(MyResult.class);
Unmarshaller unmarshaller = jc.createUnmarshaller();
unmarshaller.setProperty("eclipselink.media-type", "application/json");
File json = new File("src/forum11001458/input.json");
Object myResult = unmarshaller.unmarshal(json);
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty("eclipselink.media-type", "application/json");
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.marshal(myResult, System.out);
}
}
input.json/Output
{
"MyResult" : {
"AccountID" : "12345",
"User" : {
"Name" : "blah blah",
"Email" : "blah#blah.com"
},
"Result" : {
"Course" : "blah",
"Score" : "10.0"
}
}
}

Googles GSON is a really nice json lib. This is from the previous link and it basically outlines some of its functionality.

jackson is also pretty fast and easy to use

Although closed, this SO post can help you understand the differences between Jackson and GSON. Which one is "best" depends on what is important for you.
EDIT: Specifically for Jackson, your example looks a lot like the example they give for what they call Full Data Binding, you can read it here. Btw, although the announced 5 minutes needed to read that document is maybe a bit short, it gives a complete overview of the different ways Jackson can be used. You'll also notice that the examples given do not use annotations.

Or GSON
Super easy (no getters/settres, no annotations or configurations needed).
class BagOfPrimitives {
private int value1 = 1;
private String value2 = "abc";
private transient int value3 = 3;
}
BagOfPrimitives obj = new BagOfPrimitives();
Gson gson = new Gson();
String json = gson.toJson(obj);
==> json is {"value1":1,"value2":"abc"}

What Json library can I use for this? Jackson Library is used to serialize Java objects into JSON and deserialize JSON string into Java objects. Add the following dependencies to pom.xml.
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.4</version>
</dependency>
This dependency will transitively add the following libraries to the classpath:
jackson-annotations-2.9.4.jar
jackson-core-2.9.4.jar
jackson-databind-2.9.4.jar
**Note: Please always go with the latest jars.
How should I structure my Java object? Please see the full working code.
**MainClass.java:**
import java.io.IOException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
public class MainClass {
public static void main(String[] args) throws IOException {
ObjectMapper mapper = new ObjectMapper();
mapper.enable(SerializationFeature.INDENT_OUTPUT);
Result result = new Result();
result.setCourse("blah");
result.setScore("10.0");
User user = new User();
user.setName("blah blah");
user.setEmail("blah#blah.com");
MyResult myResult = new MyResult();
myResult.setAccountID("12345");
myResult.setResult(result);
myResult.setUser(user);
MyPojo myPojo = new MyPojo();
myPojo.setMyResult(myResult);
String jsonStr = mapper.writeValueAsString(myPojo);
System.out.println(jsonStr);
} }
**MyPojo.java:-**
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;
#JsonPropertyOrder({ "AccountID", "User", "Result" })
public class MyPojo {
private MyResult MyResult;
public MyResult getMyResult() {
return MyResult;
}
#JsonProperty("MyResult")
public void setMyResult(MyResult MyResult) {
this.MyResult = MyResult;
} }
**MyResult.java:**
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;
#JsonPropertyOrder({ "AccountID", "User", "Result" })
public class MyResult {
private User User;
private Result Result;
private String AccountID;
public User getUser() {
return User;
}
#JsonProperty("User")
public void setUser(User User) {
this.User = User;
}
public Result getResult() {
return Result;
}
#JsonProperty("Result")
public void setResult(Result Result) {
this.Result = Result;
}
public String getAccountID() {
return AccountID;
}
#JsonProperty("AccountID")
public void setAccountID(String AccountID) {
this.AccountID = AccountID;
} }
**Result.java:**
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;
#JsonPropertyOrder({ "Course", "Score" })
public class Result {
private String Course;
private String Score;
public String getCourse() {
return Course;
}
#JsonProperty("Course")
public void setCourse(String Course) {
this.Course = Course;
}
public String getScore() {
return Score;
}
#JsonProperty("Score")
public void setScore(String Score) {
this.Score = Score;
} }
**User.java:**
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;
#JsonPropertyOrder({ "Name", "Email" })
public class User {
private String Name;
private String Email;
public String getName() {
return Name;
}
#JsonProperty("Name")
public void setName(String Name) {
this.Name = Name;
}
public String getEmail() {
return Email;
}
#JsonProperty("Email")
public void setEmail(String Email) {
this.Email = Email;
}
#Override
public String toString() {
return "ClassPojo [Name = " + Name + ", Email = " + Email + "]";
} }
**Result:**
{
"MyResult" : {
"AccountID" : "12345",
"User" : {
"Name" : "blah blah",
"Email" : "blah#blah.com"
},
"Result" : {
"Course" : "blah",
"Score" : "10.0"
}
}
}
Note: Please note the use of Json Annotations like #JsonProperty("Email") to make json property names as same in the expected output & #JsonPropertyOrder({ "Name", "Email" } to maintain the sequence as in expected output. Refer: https://www.baeldung.com/jackson-annotations.