Develop Reference

Is there a way with Jackson ObjectMapper (without a custom #JsonCreator) to unmarshall this Json to the supplied Java Dto?

I have two Java classes:
public class Request
{
private List<Item> subItems;
public Request()
{
}
public List<Item> getSubItems()
{
return subItems;
}
public void setSubItems(List<Item> subItems)
{
this.subItems = subItems;
}
}
class Item
{
private String name;
private String functionName;
//...elided...
}
The subItems that will be passed can be complex (include a function) or simple (just a name). There can be a mix of these. To simplify the JSON, I'd like to be able to accept the following:
JSON:
{
"subItems": [
{
"name": "complexType",
"function": "someFunction"
},
"simpleType"
]
}
and then have this turned into the equivalent of the following instance:
Request request = new Request();
request.setSubItems(
Arrays.asList(
new Item( "complexType", "SomeFunction" ),
new Item( "simpleType" )
)
);
Is this possible with Jackson/ObjectMapper?
What settings and annotations would I need?

If your Item class has a string constructor, it will be called with the "simpleType" value.
class Item {
private String name;
private String functionName;
public Item() {
}
public Item(String name) {
this.name = name;
}
// getters and setters here
}
Full demo
public class Request {
public static void main(String[] args) throws IOException {
String json = "{\"subItems\":[" +
"{\"name\":\"complexType\",\"functionName\":\"SomeFunction\"}," +
"\"simpleType\"" +
"]}";
Request request = new ObjectMapper().readValue(json, Request.class);
System.out.println(request);
}
private List<Item> subItems;
public Request() {
}
public Request(Item... subItems) {
this.subItems = Arrays.asList(subItems);
}
public List<Item> getSubItems() {
return this.subItems;
}
public void setSubItems(List<Item> subItems) {
this.subItems = subItems;
}
#Override
public String toString() {
return "Request [subItems=" + this.subItems + "]";
}
}
class Item {
private String name;
private String functionName;
public Item() {
}
public Item(String name) {
this.name = name;
}
public Item(String name, String functionName) {
this.name = name;
this.functionName = functionName;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public String getFunctionName() {
return this.functionName;
}
public void setFunctionName(String functionName) {
this.functionName = functionName;
}
#Override
public String toString() {
return "Item [name=" + this.name + ", functionName=" + this.functionName + "]";
}
}
Output
Request [subItems=[Item [name=complexType, functionName=SomeFunction], Item [name=simpleType, functionName=null]]]

UnrecognizedPropertyException: Unrecognized field "sections"

I'm using Jackson as part of a spring boot app. I am turning JSON into Java, and I am getting this error. I did some research, but I still don't understand what is going wrong or how to fix it.
Here is the JSON fragment:
"dataBlock": {
"sections": [
{
"info": "",
"prompt": "",
"name": "First Section",
"sequence": 0,
"fields": [],
"gatingConditions": [],
"guid": "480d160c-c34f-4022-97b0-e8a1f28c49ae",
"id": -2
}
],
"prompt": "",
"id": -1,
"name": ""
}
So my Java object for this "dataBlock" element:
public class DataBlockObject {
private int id;
private String prompt;
private String name;
private List<SectionObject> sections;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getPrompt() {
return prompt;
}
public void setPrompt(String prompt) {
this.prompt = prompt;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<SectionObject> getSections() {
return sections;
}
public void setSections(List<SectionObject> sections) {
this.sections = sections;
}
}
And the Section object is this:
public class SectionObject {
private int id;
private String name;
private String prompt;
private String info;
private int sequence;
private List<FieldObject> fields;
private List<GatingConditionObject> gatingConditions;
private String guid;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPrompt() {
return prompt;
}
public void setPrompt(String prompt) {
this.prompt = prompt;
}
public String getInfo() {
return info;
}
public void setInfo(String info) {
this.info = info;
}
public int getSequence() {
return sequence;
}
public void setSequence(int sequence) {
this.sequence = sequence;
}
public List<FieldObject> getFields() {
return fields;
}
public void setFields(List<FieldObject> fields) {
this.fields = fields;
}
public List<GatingConditionObject> getGatingConditions() {
return gatingConditions;
}
public void setGatingConditions(List<GatingConditionObject> gatingConditions) {
this.gatingConditions = gatingConditions;
}
public String getGuid() {
return guid;
}
public void setGuid(String guid) {
this.guid = guid;
}
}
So it seems to me that Jackson would make a DataBlockObject, map the obvious elemenets, and create an array that I have clearly marked as a List named sections. -- just like the JSON shows.
Now the error is:
Caused by: com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "sections" (class com.gridunity.workflow.bean.json.SectionObject), not marked as ignorable (8 known properties: "gatingConditions", "sequence", "prompt", "fields", "id", "info", "guid", "name"])
Now according to that error it would seem that one of my 8 elements should be named "sections" - But that's not one of my elements. It clearly has a problem with my List of Sections, but I cant figure out what it is.
Can someone explain WHY this is happening, especially sence it looks like I have my structure correct, and how to fix this. I have seen this on other posts:
objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
But that seems incredibly wrong as I know all of my properties.

It looks like the JSON itself has another sections field in one or more of the dataBlock.sections items. If you don't have control over the construction of the JSON object, you'll need to add a #JsonIgnoreProperties annotation on the SectionObject class so that when the JSON object has fields that aren't specified in the POJO, it won't throw an error during deserialization.
#JsonIgnoreProperties(ignoreUnknown = true)
public class SectionObject {
// class members and methods here
}

Trouble converting Json Array into Pojo with array of pojos

JSON String
{
"order":{
"address":{
"city":"seattle"
},
"orderItem":[
{
"itemId":"lkasj",
"count":2
},
{
"itemId":"ldka",
"count":3
}
]
}
}
Order Class
public class Order {
private OrderItem[] orderItems;
private CustomerAddress address;
Order(OrderItem[] orderItems, CustomerAddress address ) {
this.orderItems = orderItems;
this.address = address;
}
public OrderItem[] getOrderItems() {
return orderItems;
}
public void setOrderItems(OrderItem[] orderItems) {
this.orderItems = orderItems;
}
public CustomerAddress getAddress() {
return address;
}
public void setAddress(CustomerAddress address) {
this.address = address;
}
}
My OrderItem class
package com.cbd.backend.model;
import org.springframework.data.annotation.Id;
public class OrderItem {
#Id
private String id;
private String itemId;
private String count;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
unit Test that blows up
public String getItemId() {
return itemId;
}
public void setItemId(String itemId) {
this.itemId = itemId;
}
public String getCount() {
return count;
}
public void setCount(String count) {
this.count = count;
}
}
Unit test to demonstrate issue
package com.cbd.backend.model;
import com.google.gson.Gson;
import org.junit.Test;
import static org.junit.Assert.*;
public class OrderTest {
Gson gson = new Gson();
#Test
public void gsonToOrder() {
Order order = gson.fromJson( a, Order.class );
assertNotNull(order);
assertNotNull(order.getOrderItems()[0]);
}
private final String a = "{ \"order\": { \"address\": { \"city\": \"seattle\" },\"orderItem\":[{ \"itemId\":\"lkasj\", \"count\":2 }, { \"itemId\":\"ldka\", \"count\":3 } ] } }";
}
Should I be using something other than gson or am i constructing this incorrectly

There are two problems in your code:
The root element of your JSON is "order", but the class does not have a property with this name. Try changing you model or just removing the element from the JSON.
There is a mismatch in the name of the "orderItem" property. It is plural in the class, but singular in the JSON.
To sum it up, the following JSON will work without any changes to the code.
{
"address":{
"city":"seattle"
},
"orderItems":[
{
"itemId":"lkasj",
"count":2
},
{
"itemId":"ldka",
"count":3
}
]
}
Also, "count" as it appears in the JSON seems to be numeric, so you might want to change the type of OrderItem.count to int or java.lang.Integer.

How to map Riot Api request to an Object with Spring RestTemplate

I am using Spring's RestTemplate to convert a JSON response from the RiotAPI into my BasicSummoner object. I believe the issue is with converting the JSON response into my object. After calling getForObject() all of the object's fields are null/empty. Any help is appreciated as this is my first Spring project and first time using Riot's API.
I have verified that the JSON resonse is correct and looks like this:
{
"riotschmick": {
"id": 585897,
"name": "RiotSchmick",
"profileIconId": 782,
"summonerLevel": 30,
"revisionDate": 1469155559000
}
}
My request looks like this:
public BasicSummoner requestBasicSummoner() {
RestTemplate template = new RestTemplate();
String mes = "https://na.api.pvp.net/api/lol/na/v1.4/summoner/by-name/RiotSchmick?api_key=<my-api-key>";
BasicSummoner summoner = template.getForObject(mes, BasicSummoner.class);
log.info(summoner.toString());
return summoner;
}
And the object BasicSummoner looks like this:
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
#JsonIgnoreProperties(ignoreUnknown = true)
public class BasicSummoner {
private long id;
private String name;
private int profileIconId;
private long revisionDate;
private long summonerLevel;
public BasicSummoner() {
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getProfileIconId() {
return profileIconId;
}
public void setProfileIconId(int profileIconId) {
this.profileIconId = profileIconId;
}
public long getRevisionDate() {
return revisionDate;
}
public void setRevisionDate(long revisionDate) {
this.revisionDate = revisionDate;
}
public long getSummonerLevel() {
return summonerLevel;
}
public void setSummonerLevel(long summonerLevel) {
this.summonerLevel = summonerLevel;
}
#Override
public String toString() {
return "id=" + id + ", name=" + name + " , summoner level=" + summonerLevel;
}
}

Your JSON is not a single Object, but an Object inside another Object.
This means that to use your code as it is now, you need to unwrap the inner Object, or change the structure to something else.
The response seems to fit a Map<String, BasicSummoner>

Binding json, that has a list, with an object using Jackson

Given I have the following json:
{
"Company": {
"name": "cookieltd",
"type": "food",
"franchise_location": [
{
"location_type": "town",
"address_1": "5street"
},
{
"location_type": "village",
"address_1": "2road"
}
]
}
}
How can it be binded to the following object classes using Jackson?:
1) Company class
public class Company
{
String name, type;
List<Location> franchise_location = new ArrayList<Location>();
[getters and setters]
}
2) Location class
public class Location
{
String location_type, address_1;
[getters and setters]
}
I have done:
String content = [json above];
ObjectReader reader = mapper.reader(Company.class).withRootName("Company"); //read after the root name
Company company = reader.readValue(content);
but I am getting:
com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "franchise_location"

As far as I can tell, you are simply missing an appropriately named getter for the field franchise_location. It should be
public List<Location> getFranchise_location() {
return franchise_location;
}
(and the setter)
public void setFranchise_location(List<Location> franchise_location) {
this.franchise_location = franchise_location;
}
Alternatively, you can annotate your current getter or field with
#JsonProperty("franchise_location")
private List<Location> franchiseLocation = ...;
which helps to map JSON element names that don't really work with Java field name conventions.
The following works for me
public static void main(String[] args) throws Exception {
String json = "{ \"Company\": { \"name\": \"cookieltd\", \"type\": \"food\", \"franchise_location\": [ { \"location_type\": \"town\", \"address_1\": \"5street\" }, { \"location_type\": \"village\", \"address_1\": \"2road\" } ] } }";
ObjectMapper mapper = new ObjectMapper();
ObjectReader reader = mapper.reader(Company.class).withRootName(
"Company"); // read after the root name
Company company = reader.readValue(json);
System.out.println(company.getFranchise_location().get(0).getAddress_1());
}
public static class Company {
private String name;
private String type;
private List<Location> franchise_location = new ArrayList<Location>();
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public List<Location> getFranchise_location() {
return franchise_location;
}
public void setFranchise_location(List<Location> franchise_location) {
this.franchise_location = franchise_location;
}
}
public static class Location {
private String location_type;
private String address_1;
public String getLocation_type() {
return location_type;
}
public void setLocation_type(String location_type) {
this.location_type = location_type;
}
public String getAddress_1() {
return address_1;
}
public void setAddress_1(String address_1) {
this.address_1 = address_1;
}
}
and prints
5street

my solution for JSON is always GSON, you can do some research on that, as long as you have the correct structure of class according to the JSON, it can automatically transfer from JSON to object:
Company company = gson.fromJson(json, Company.class);
GSON is so smart to do the convertion thing!
enjoy GSON !