Develop Reference

How to map a complex JSON with POJO

I'm having some trouble with how to map a JSON correctly. I have to save this incoming JSON in my DB:
{
"request": {
"Target": "Affiliate_Offer",
"Format": "json",
"Service": "HasOffers",
"Version": "2",
"api_key": "3225235c56334584b1360d",
"Method": "findAll",
"contain": [
"Country"
]
},
"response": {
"status": 1,
"httpStatus": 200,
"data": {
"18292": {
"Offer": {
"id": "18292",
"name": "247 Profit Formula",
"approval_status": "approved"
},
"Country": {
"US": {
"id": "840",
"code": "US",
"name": "United States",
"regions": {
"4": {
"id": "4",
"country_code": "US",
"country_code_3c": "USA",
"code": "AR",
"name": "Arkansas"
},
"5": {
"id": "5",
"country_code": "US",
"country_code_3c": "USA",
"code": "CA",
"name": "California"
},
"10": {
"id": "10",
"country_code": "US",
"country_code_3c": "USA",
"code": "FL",
"name": "Florida"
}
},
"CA": {
"id": "124",
"code": "CA",
"name": "Canada",
"regions": []
}
}
},
"17823": {
"Offer": {
"id": "17823",
"name": "American Career Guide",
"approval_status": null
},
"Country": {
"Country": {
"US": {
"id": "840",
"code": "US",
"name": "United States",
"regions": []
},
"UK": {
"id": "826",
"code": "UK",
"name": "United Kingdom",
"regions": []
},
"AU": {
"id": "36",
"code": "AU",
"name": "Australia",
"regions": []
},
"CA": {
"id": "124",
"code": "CA",
"name": "Canada",
"regions": []
},
"NZ": {
"id": "554",
"code": "NZ",
"name": "New Zealand",
"regions": []
}
}
}
},
The Offer structure is already mapped, but I'm having some trouble with the Country.
The OfferMapper:
#Data
#AllArgsConstructor
#NoArgsConstructor
#JsonIgnoreProperties(ignoreUnknown = true)
public class OfferMapper {
OfferRequest request;
OfferResponse response;
}
The OfferResponse:
#Getter #Setter
#JsonIgnoreProperties(ignoreUnknown = true)
public class OfferResponse {
#JsonProperty("status")
private int status;
#JsonProperty("httpStatus")
private int httpStatus;
#JsonProperty("data")
private Map<String, OfferData> data;
}
Here is the structure that I'm having trouble. The OfferData:
#Getter #Setter
#JsonIgnoreProperties(ignoreUnknown = true)
public class OfferData {
#JsonProperty("Offer")
Offer offer;
#JsonProperty("Country")
Country country;
}
I tried to put in a map like this Map<Country, String> countries; and List<Map<Country, String>> countries; no luck so far to arrange this part with a POJO:
"Country": {
"US": {
"id": "840",
"code": "US",
"name": "United States",
"regions": []
}
}

"Country": {
"US": {
"id": "840",
"code": "US",
"name": "United States",
"regions": []
}
}
It is equivalent to receiving an object of Country that has an object of US.
Structure of US
public class US
{
private String id;
private String code;
private String name;
private List<String> regions; //if regions is gonna be list of strings
//getters and setters
}

Your Json Country is having letter C as capital hence it might be the issue that Jackson is not recognizing it. Check Java Naming conventions and other docs for more information.
class Data {
private String id;
private String code;
private String name;
private List<String> regions;
}
class CountryData {
public Map<String, Data> getCountry() {
return Country;
}
public void setCountry(Map<String, Data> Country) {
Country = Country;
}
//To resolve the error you need to add the below tag and define your class accordingly.
#JsonProperty("Country")
private Map<String, Data> Country;
}
public class POJO {
public static void main(String[] args) throws JsonProcessingException {
String countryjson = "{\n" +
" \"Country\": {\n" +
" \"US\": {\n" +
" \"id\": \"840\",\n" +
" \"code\": \"US\",\n" +
" \"name\": \"United States\",\n" +
" \"regions\": []\n" +
" },\n" +
" \"UK\": {\n" +
" \"id\": \"826\",\n" +
" \"code\": \"UK\",\n" +
" \"name\": \"United Kingdom\",\n" +
" \"regions\": []\n" +
" },\n" +
" \"AU\": {\n" +
" \"id\": \"36\",\n" +
" \"code\": \"AU\",\n" +
" \"name\": \"Australia\",\n" +
" \"regions\": []\n" +
" },\n" +
" \"CA\": {\n" +
" \"id\": \"124\",\n" +
" \"code\": \"CA\",\n" +
" \"name\": \"Canada\",\n" +
" \"regions\": []\n" +
" },\n" +
" \"NZ\": {\n" +
" \"id\": \"554\",\n" +
" \"code\": \"NZ\",\n" +
" \"name\": \"New Zealand\",\n" +
" \"regions\": []\n" +
" }\n" +
" }\n" +
"}";
ObjectMapper objectMapper = new ObjectMapper();
CountryData country = objectMapper.readValue(countryjson, CountryData.class);
System.out.println(country.toString());
}
}
It should work, Add #JsonProperty Tag in you POJO definition.

Obtaining value from Json using Gson get()

Given the following Json data:
"values": [
{
"type": "any",
"value": "MO918038B",
"key": "nino"
},
{
"type": "any",
"value": "1956-11-18",
"key": "dob"
},
{
"type": "any",
"value": "q",
"key": "memorableWord"
},
{
"type": "any",
"value": "E13468",
"key": "pin"
},
]
And the following Java class:
public void doStuff() {
try (Reader reader = new FileReader("global-vars.json")) {
JsonObject json = new Gson().fromJson(reader, JsonObject.class);
String reg = json.get("values").toString();
System.out.println(reg);
} catch (IOException e) {
e.printStackTrace();
}
}
I'm not clear, after searching, how best to obtain the "value" of, for example, "nino" which is = "MO918038B"

Type listType = new TypeToken<List<YourObjectClass>>() {}.getType();
List<YourObjectClass> yourList = new Gson().fromJson(yourJson, listType);

Since your posted JSON isn't RFC 4627 conformant, I assume this array is inside of an object.
Code would look like this:
public class YourClass {
class Value {
public String type;
public String value;
public String key;
}
public Value[] values;
}
public class App{
public static void main(String[] args) {
String json = "{ \"values\": [\n" +
"{\n" +
" \"type\": \"any\",\n" +
" \"value\": \"MO918038B\",\n" +
" \"key\": \"nino\"\n" +
"},\n" +
"{\n" +
" \"type\": \"any\",\n" +
" \"value\": \"1956-11-18\",\n" +
" \"key\": \"dob\"\n" +
"},\n" +
"{\n" +
" \"type\": \"any\",\n" +
" \"value\": \"q\",\n" +
" \"key\": \"memorableWord\"\n" +
"},\n" +
"{\n" +
" \"type\": \"any\",\n" +
" \"value\": \"E13468\",\n" +
" \"key\": \"pin\"\n" +
"}\n" +
"]}";
YourClass yourClass = new Gson().fromJson(json, YourClass.class);
for (YourClass.Value value : yourClass.values) {
if (value.key.equals("nino")) {
System.out.println(value.value);
}
}
}
}

How to read a array value form json in java

I have following json data:-
{
"store": {
"book": [
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
},
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
},
{
"category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}
],
"bicycle": {
"color": "red",
"price": 19.95
}
},
"expensive": 10
}
Method to assert json:-
public void assertJsonvalue (String description, String jsonString,
String path, Object expectedValue) {
ObjectMapper objectMapper = new ObjectMapper();
Map<String, Object> jsonMap = null;
try {
jsonMap = objectMapper.readValue(jsonString,
new TypeReference<Map<String, Object>>() {
});
} catch (IOException e) {
fail("Could not parse json from string:" + jsonString);
}
Object actualValue = null;
try {
actualValue = PropertyUtils.getProperty(jsonMap, path);
System.out.println("actualValue" + actualValue);
} catch (IllegalAccessException e) {
// error here
}
assertEquals(description, expectedValue, actualValue);
}
When I try to get json value from by using the following, Its works well.
assertJsonValue("bicycle color", json, "store.bicycle.color", "red");
I want to get array value from json such as details of 1st book.
I have tried the following, that doesn't help me out.
json paths are as follows:-
"store.book[0]"
"store.book.[0]"
"store.book.category"
How Can I do this ?

According to this answer, you should be able to get the mentioned properties like this:
assertJsonValue("...", json, "store.(book)[0].category", "reference");
Edit:
Which version of jackson and beanutils are you using? I've modified your method a bit and made a simple test case, using beanutils 1.9.2 and jackson 2.6.5 tests seem to pass:
import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.commons.beanutils.PropertyUtils;
import org.junit.Test;
import java.io.IOException;
import static org.junit.Assert.*;
public class TestJson {
private static final String JSON = "{\n" +
" \"store\": {\n" +
" \"book\": [\n" +
" {\n" +
" \"category\": \"reference\",\n" +
" \"author\": \"Nigel Rees\",\n" +
" \"title\": \"Sayings of the Century\",\n" +
" \"price\": 8.95\n" +
" }\n" +
" ],\n" +
" \"bicycle\": {\n" +
" \"color\": \"red\",\n" +
" \"price\": 19.95\n" +
" }\n" +
" },\n" +
" \"expensive\": 10\n" +
"}";
#Test
public void testJson() {
assertTrue(assertJsonValue(JSON, "store.(book)[0].category", "reference"));
assertTrue(assertJsonValue(JSON, "store.(book)[0].author", "Nigel Rees"));
assertTrue(assertJsonValue(JSON, "store.(book)[0].title", "Sayings of the Century"));
assertTrue(assertJsonValue(JSON, "store.(book)[0].price", 8.95));
}
public boolean assertJsonValue(String jsonString,
String path,
Object expectedValue) {
ObjectMapper objectMapper = new ObjectMapper();
try {
Object actual = PropertyUtils
.getProperty(objectMapper.readValue(jsonString, Object.class), path);
if (actual.equals(expectedValue)) {
return true;
}
} catch (IOException | ReflectiveOperationException e) {
// handle error
}
return false;
}
}

How to format the output to proper json format?

I have a dynamic web project where in my jsp page, on clicking a form, it retrieves the data from elasticsearch and displays in the UI in proper json format as Key:value pair.
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String start = request.getParameter("start");
String end = request.getParameter("end");
String line1;
StringBuffer jsonString1 = new StringBuffer();
try {
URL url1 = new URL("http://localhost:9200/indexname/_search?filter_path=hits.hits._source&pretty=1&size=100000");
String payload1 = "{\"query\":{\"filtered\":{\"filter\":{\"range\":{\"Date\":{\"lte\":\""+end+"\",\"gte\":\""+start+"\"}}}}},\"_source\":{\"include\":[\"ID\",\"Name\",\"Status\",\"Date\"]}}";
HttpURLConnection connection1 = (HttpURLConnection) url1.openConnection();
connection1.setDoInput(true);
connection1.setDoOutput(true);
connection1.setRequestMethod("POST");
connection1.setRequestProperty("Accept", "application/json");
connection1.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
OutputStreamWriter writer1 = new OutputStreamWriter(connection1.getOutputStream(), "UTF-8");
writer1.write(payload1);
writer1.close();
BufferedReader br1 = new BufferedReader(new InputStreamReader(connection1.getInputStream()));
while ((line1 = br1.readLine()) != null) {
jsonString1.append(line1);
}
br1.close();
file1.close();
connection1.disconnect();
} catch (Exception e) {
throw new RuntimeException(e.getMessage());
}
response.setContentType("application/json");
// JSONObject jsonObj = new JSONObject(jsonString1.toString()); //JSONObject cannot be resolved to a type error is getting displayed.
//System.out.println("---------------------------");
// System.out.println(jsonObj);
PrintWriter out = response.getWriter();
out.print(jsonString1); //Here instead of String buffer I want to send a json object or an arraylist which outputs just the key value pair by removing all unwanted characters.
out.flush();
out.close();
}
In m HTML, on performing a Submit operation, it displays something like this :
{ "hits" : { "hits" : [ { "_source":{"ID":"123","Status":"false","Name":"ABC_123","Date":"2010-08-16T11:07:48"} }, { "_source":{"ID":"124","Status":"false","Name":"ABC_678","Date":"2010-08-16T12:00:12"} }, { "_source":{"ID":"125","Status":"true","Name":"FGH_122","Date":"2010-08-16T12:01:48"} }, { "_source":{"ID":"126","Status":"false","Name":"TYT_333","Date":"2010-08-16T12:06:48"} }, { "_source":{"ID":"127","Status":"false","Name":"CVF_230","Date":"2010-08-16T12:07:18"} }, { "_source":{"ID":"128","Status":"true","Name":"AWE_101","Date":"2010-08-16T12:03:48"} }, { "_source":{"ID":"129","Status":"true","Name":"WEC_299","Date":"2010-08-16T12:07:29"} } ] }}
Instead, I want to display in my UI some alert box or something like that where it displays
{"ID":"123","Status":"false","Name":"ABC_123","Date":"2010-08-16T11:07:48"},
{"ID":"124","Status":"false","Name":"ABC_678","Date":"2010-08-16T12:00:12"},
{"ID":"125","Status":"true","Name":"FGH_122","Date":"2010-08-16T12:01:48"}
etc....
Any idea on how I can achieve this? Please advice. Thanks.

Do a classic iteration of your json string, before PrintWriter step
String jsonString1 = "{ \"hits\": { \"hits\": [{ \"_source\": { \"ID\": \"123\", \"Status\": \"false\", \"Name\": \"ABC_123\", \"Date\": \"2010-08-16T11:07:48\" } }, { \"_source\": { \"ID\": \"124\", \"Status\": \"false\", \"Name\": \"ABC_678\", \"Date\": \"2010-08-16T12:00:12\" } }, { \"_source\": { \"ID\": \"125\", \"Status\": \"true\", \"Name\": \"FGH_122\", \"Date\": \"2010-08-16T12:01:48\" } }, { \"_source\": { \"ID\": \"126\", \"Status\": \"false\", \"Name\": \"TYT_333\", \"Date\": \"2010-08-16T12:06:48\" } }, { \"_source\": { \"ID\": \"127\", \"Status\": \"false\", \"Name\": \"CVF_230\", \"Date\": \"2010-08-16T12:07:18\" } }, { \"_source\": { \"ID\": \"128\", \"Status\": \"true\", \"Name\": \"AWE_101\", \"Date\": \"2010-08-16T12:03:48\" } }, { \"_source\": { \"ID\": \"129\", \"Status\": \"true\", \"Name\": \"WEC_299\", \"Date\": \"2010-08-16T12:07:29\" } }] }}";
JSONObject jsonObj = new JSONObject(jsonString1);
JSONObject c = jsonObj.getJSONObject("hits");
JSONArray c1 = c.getJSONArray("hits");
// Iterate hits array
for (int i = 0 ; i < c1.length(); i++) {
JSONObject jObject = c1.getJSONObject(i);
System.out.println(jObject.get("_source"));
}
Resultant data looks like,
{"Name":"ABC_123","Status":"false","Date":"2010-08-16T11:07:48","ID":"123"}
{"Name":"ABC_678","Status":"false","Date":"2010-08-16T12:00:12","ID":"124"}
{"Name":"FGH_122","Status":"true","Date":"2010-08-16T12:01:48","ID":"125"}
{"Name":"TYT_333","Status":"false","Date":"2010-08-16T12:06:48","ID":"126"}
{"Name":"CVF_230","Status":"false","Date":"2010-08-16T12:07:18","ID":"127"}
{"Name":"AWE_101","Status":"true","Date":"2010-08-16T12:03:48","ID":"128"}
{"Name":"WEC_299","Status":"true","Date":"2010-08-16T12:07:29","ID":"129"}
As well checkout Demo, It's a client side iteration. If you can able to do it in client side this may help you.

GSON parsing fromJSON regarding arrays of objects exception

I am using google's GSON parsing library and I'm not sure if this has been asked before (I did check what I could find) but, here I go!! It's regarding the fromJSON method and how it refuses to interpret some classes as arrays.
Given the JSON structure below:
{"visualization": {
"root": {
"fullname": "CC/dudu",
"name": "dudu",
"type": "String",
"children": [
{
"fullname": "CC/dudu/lulu",
"name": "lulu",
"type": "String"
}
]
},
"traces": {
"messages": [
{
"from": "dudu",
"method": "call()",
"scenario": "#1",
"timestamp": "09-12-2013 00:21:14",
"to": "dudu",
"type": "void",
"violation": "true",
"visible": "true"
}
],
"scenarios": [
{
"name": "testscenario",
"id": "#1",
"description": "testing parsing!"
}
]
}
}}
And the accompanying contained classes.
public class Response {
private Visualization visualization;
//+getter/setter
}
public class Visualization {
private Component root;
private Map<String, Trace> traces;
//+getter/setter
}
public class Trace {
private ArrayList<Message> messages;
private ArrayList<Scenario> scenarios;
//+getter/setter
}
I get the error that GSON was expecting an Object and NOT an Array (before the "[" token of messages). Anyone know why that is? The types (as can be seen in the classes) are List, so it should be fine. And I have tried having more objects in the array and I still get the same error message! Why is Gson interpreting the List<TypeA> type as an object and not an array?
EDIT:
Here's the code code, but it's kinda pointless, since the exception is being thrown because of the parsing process. I doubt you'll find anything useful. "visualization" is a string with a correct JSON format.
Gson gsonParser = new Gson();
Response r = gsonParser.fromJson(visualization, Response.class);

The code below allows you to parse exactly your JSON.
Note that I put all into a class to make easier for you to test it. Anycase, Gson does not work well with inner classes unless they are static. So I suggest you to make a file for each class or use only static inner classes.
package stackoverflow.questions;
import java.util.*;
import com.google.gson.Gson;
public class Q20461706 {
public class Trace {
ArrayList<Message> messages;
ArrayList<Scenario> scenarios;
#Override
public String toString() {
return "Trace [messages=" + messages + ", scenarios=" + scenarios + "]";
}
}
public static class Message {
String from; // "from": "dudu",
String method; // "method": "call()",
String scenario; // "scenario": "#1",
String timestamp; // "timestamp": "09-12-2013 00:21:14",
String to; // "to": "dudu",
String type; // "type": "void",
Boolean violation; // "violation": "true",
Boolean visible; // "visible": "true"
#Override
public String toString() {
return "Message [from=" + from + ", method=" + method + ", scenario=" + scenario + ", timestamp=" + timestamp + ", to=" + to + ", type=" + type + ", violation=" + violation + ", visible=" + visible + "]";
}
}
public static class Scenario {
String name;// "name": "testscenario",
String id; // "id": "#1",
String description; // "description": "testing parsing!"
#Override
public String toString() {
return "Scenario [name=" + name + ", id=" + id + ", description=" + description + "]";
}
}
public static class Component {
String fullname; // "fullname": "CC/dudu",
String name; // "name": "dudu",
String type; // "type": "String",
List<Component> children;
#Override
public String toString() {
return "Component [fullname=" + fullname + ", name=" + name + ", type=" + type + ", children=" + children + "]";
}
}
public static class Visualization {
Component root;
Trace traces;
#Override
public String toString() {
return "Visualization [root=" + root + ", traces=" + traces + "]";
}
}
public static class Response {
Visualization visualization;
#Override
public String toString() {
return "Response [visualization=" + visualization + "]";
}
}
public static void main(String[] args) {
String json =
" {\"visualization\": { "+
" \"root\": { "+
" \"fullname\": \"CC/dudu\", "+
" \"name\": \"dudu\", "+
" \"type\": \"String\", "+
" \"children\": [ "+
" { "+
" \"fullname\": \"CC/dudu/lulu\", "+
" \"name\": \"lulu\", "+
" \"type\": \"String\" "+
" } "+
" ] "+
" }, "+
" \"traces\": { "+
" \"messages\": [ "+
" { "+
" \"from\": \"dudu\", "+
" \"method\": \"call()\", "+
" \"scenario\": \"#1\", "+
" \"timestamp\": \"09-12-2013 00:21:14\", "+
" \"to\": \"dudu\", "+
" \"type\": \"void\", "+
" \"violation\": \"true\", "+
" \"visible\": \"true\" "+
" } "+
" ], "+
" \"scenarios\": [ "+
" { "+
" \"name\": \"testscenario\", "+
" \"id\": \"#1\", "+
" \"description\": \"testing parsing!\" "+
" } "+
" ] "+
" } "+
" }} ";
Gson gsonParser = new Gson();
Response r = gsonParser.fromJson(json, Response.class);
System.out.println(r);
}
}
To respond to your question, note that I changed your Visualization class with Trace traces since you have only a Trace object in your JSON and not an array. This is why Gson complains.
Note also that I avoided to parse the date as date, you need to specify a custom date format for that, but it's beyond the scope of this question. You can find many examples here on SO.