I parse server JSON response with GSON library. Backend guys sometimes tell me: "We can't specify variable type in JSON for some reason" (old php, they don't know how to do it and so on and so forth).
GSON likes strong typing in its object model. So I can't parse Object as String.
GSON wait for:
{
"service":{
"description":null,
"name":"Base",
"id":"4c7a90410529"
}
}
But it gets (empty data):
"service": ""
And I get
java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1396
What is the best practice to parse such response?
Another question:
How can I build object, it can recognize Integer variable which returned from time to time as Integer or as String? The same server side issue.
"data": "1"
or
"data": 1
I know - we should use specific types in Java. But sometime it is worth to make concessions,
Thanks
EDIT:
My solution based on Java Developer's answer.
ServiceDeserializer class deserialize every object depending on its internal value.
public class ServiceDeserializer implements JsonDeserializer<ServiceState>{
#Override
public ServiceState deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
String name = "";
String uuid = "";
String description = "";
if (json.isJsonObject()) {
JsonObject obj = json.getAsJsonObject();
if (!obj.get("name").isJsonNull()) {
name = obj.get("name").getAsString();
}
if (!obj.get("uuid").isJsonNull()) {
uuid = obj.get("uuid").getAsString();
}
if (!obj.get("description").isJsonNull()) {
description = obj.get("description").getAsString();
}
}
return new ServiceState(name, uuid, description);
}
}
And my GSON constructor with type adapter for ServiceState.
Gson gson = new GsonBuilder()
.registerTypeAdapter(ServiceState.class, new ServiceDeserializer())
.create();
You need to scrape the JSON response before trying to deserialize it into your Response Java object. You can make use of Java org.json parser to verify that service object actually exists and fix it otherwise.
String json = "{\"service\":{\r\n" +
" \"description\":null,\r\n" +
" \"name\":\"Base\",\r\n" +
" \"id\":\"4c7a90410529\"\r\n" +
"}}";
String json2 = "{\"service\":\"\"}";
JSONObject root = new JSONObject(json);
// JSONObject root = new JSONObject(json2);
if (root.optJSONObject("service") == null) {
root.put("service", new JSONObject());
}
Gson gson = new Gson();
Response response = gson.fromJson(root.toString(), Response.class);
System.out.println(response.getService());
Output :
// for JSONObject root = new JSONObject(json);
Service [id=4c7a90410529, name=Base, description=null]
// for JSONObject root = new JSONObject(json2);
Service [id=null, name=null, description=null]
Secondly, Gson is smart enough to do simple conversions like String to Integer etc. So, deserializing such JSON properties shouldn't give you any troubles.
System.out.println(gson.fromJson("10", Integer.class)); // 10
System.out.println(gson.fromJson("\"20\"", Integer.class)); // 20
If you want to stick with strictly gson you can provide a custom deserializer. Since we know that service is either a property of the base json string or embedded within some other property, we can use the deserializer to step-wise parse out the offending components and handle them accordingly.
public class MyJsonDeserializer implements JsonDeserializer<YourParsedData> {
#Override
public YourParsedData deserialize(final JsonElement je, final Type type, final JsonDeserialization Context jdc) throws JsonParseException
{
final JsonObject obj = je.getAsJsonObject(); //our original full json string
final JsonElement serviceElement = obj.get("service");
//here we provide the functionality to handle the naughty element. It seems emtpy string is returned as a JsonPrimitive... so one option
if(serviceElement instanceOf JsonPrimitive)
{
//it was empty do something
}
return YourParsedData.create(); //provide the functionality to take in the parsed data
}
}
The custom deserializer would be called as follows:
final Gson gson = new GsonBuilder().registerTypeAdapter(YourParsedData.class, new MyJsonDeserializer()).create();
gson.fromJson("{service: ''}", YourParsedData.class);
I typed all this up so if I missed some syntax my apologies.
Your json is invalid and any Json parser wouldn't be able to parse a syntactically incorrect json:
"service": {
"description": null,
"name": "Base",
"id": "4c7a90410529"
}
should be encapsulated in curly braces as mentioned here:
{
"service": {
"description": null,
"name": "Base",
"id": "4c7a90410529"
}
}
A json structure is enclosed within {}. Your response seems to be missing that. You can manually append { and } at the beginning and end of the string to make it into a valid json structure.
Once this is done, you can use Gson to parse your json response normally.
What is the best practice to parse such response?
Use a good enough Json parser. That's more than enough. And try to have a class representing the exact same Structure as the response to avoid parsing the json responses level by level, manually.
Related
I have a Java POJO
public class TagBean {
private String type;
private String id;
public TagBean(String type, String id) {
this.type = type;
this.id = id;
}
// getters
// setters
}
I'm building pojo's and adding them to a List, as
....
List<TagBean> channelsList = new ArrayList<>();
List<TagBean> showsList = new ArrayList<>();
for each <business logic> {
if value=channels {
channelsList.add(new TagBean(...));
}
if value=shows {
showsList.add(new TagBean(...));
}
}
Gson gson = new GsonBuilder().create();
JsonObject tjsonObject = new JsonObject();
tjsonObject.addProperty("channels", gson.toJson(channelsList));
tjsonObject.addProperty("shows", gson.toJson(showsList));
JsonObject mainjsonObject = mainjsonObject.add("tags", tjsonObject);
return mainjsonObject;
My output is:
{
"tags": {
"channels": "[{\"type\":\"channel\",\"id\":\"channel\",\"name\":\"Channel\",\"parent\":\"SXM\"}]",
"shows": "[{\"type\":\"shows\",\"id\":\"shows\",\"name\":\"Shows\",\"parent\":\"SXM\"},{\"type\":\"shows\",\"id\":\"howard\",\"name\":\"Howard Stern\",\"parent\":\"shows\"},{\"type\":\"shows\",\"id\":\"howardstern\",\"name\":\"Howard Stern\",\"parent\":\"howard\"}]",
"sports": "[]"
}
}
How can i remove the backslashes? So the output is like:
{
"tags": {
"channels": " [{"type":"channel","id":"channel","name":"Channel","parent":"SXM"}]",
"shows": "[{"type":"shows","id":"shows","name":"Shows","parent":"SXM"},{"type":"shows","id":"howard","name":"Howard Stern","parent":"shows"}....
There were few other posts, but none explained this.
The problem is caused by this:
tjsonObject.addProperty("channels", gson.toJson(channelsList));
What that is doing is converting channelsList to a string containing a representation of the list in JSON, then setting the property to that string. Since the string contains JSON meta-characters, they must be escaped when the strings are serialized ... a second time.
I think that you need to do this instead:
tjsonObject.add("channels", gson.toJsonTree(channelsList));
That should produce this:
{
"tags": {
"channels":
[{"type":"channel","id":"channel","name":"Channel","parent":"SXM"}],
"shows":
[{"type":"shows","id":"shows","name":"Shows","parent":"SXM"},
{"type":"shows","id":"howard","name":"Howard Stern","parent":"shows"}
....
That is slightly different to what your question asked for, but it has the advantage of being syntactically valid JSON!
String mainJsonStr = mainjsonObject.toString();
mainJsonStr = mainJsonStr.replace("\\\\", ""); //replace the \
System.out.println(mainJsonStr);
The problem is that gson.toJson returns a String, and
tjsonObject.addProperty("channels", gson.toJson(channelsList));
this will add channels as a string and not as a JSON object.
One possible solution is to convert the string returned from gson.toJson to JSON object first then add it to the parent JSON object like
Gson gson = new GsonBuilder().create();
JsonObject tjsonObject = new JsonObject();
tjsonObject.put("channels", new JsonObject(gson.toJson(channelsList)));
tjsonObject.put("shows", new JsonObject(gson.toJson(showsList)));
this will treat channels and shows as JSON object
All strings in java have to escape quotes in them. So jsonInString should have slashes in it. When you output jsonInString though it shouldn't have the quotes. Are you looking at it in a debugger or something?
Just parse json directly and check - will get the output
above solution is not working anymore since GSON 2.8.*
use gson.toJsonTree(jsonText).getAsString(); instead
I am consuming an external API to which the response body is a String in JSON format. I am using Gson to parse the String into a JSON Object. However, I get the following error when trying to display the object in browser.
SyntaxError: JSON.parse: unexpected character at line 1 column 1 of
the JSON data
Here is my code:
Controller
#RequestMapping("/player")
public JsonArray displayPlayer() throws Exception{
String player = "PacSnackz";
smite.createSession();
String test = smite.getPlayer(player);
JsonArray playerObj = new JsonParser().parse(test).getAsJsonArray();
return playerObj;
}
Smite Class
public String getPlayer(String player) throws Exception {
if (!isSessionValid() && !createSession()) return "session null";
return getURL(combine(new String[] {
baseURL + "getplayer" + responseFormat,
devID,
getSignature("getplayer"),
sessionID,
getTimestamp(),
player
}, "/"));
}
This is what the JSON String looks like:
JSON String
[{"Avatar_URL":"","Created_Datetime":"8\/16\/2016 4:30:14 AM","Id":9993055,"Last_Login_Datetime":"4\/23\/2018 8:47:56 PM","Leaves":3,"Level":17,"Losses":19,"MasteryLevel":1,"Name":"PacSnackz","Personal_Status_Message":"","Rank_Stat_Conquest":0,"Rank_Stat_Duel":0,"Rank_Stat_Joust":0,"RankedConquest":{"Leaves":0,"Losses":0,"Name":"League","Points":0,"PrevRank":0,"Rank":0,"Rank_Stat_Conquest":null,"Rank_Stat_Duel":null,"Rank_Stat_Joust":null,"Season":0,"Tier":0,"Trend":0,"Wins":0,"player_id":null,"ret_msg":null},"RankedDuel":{"Leaves":0,"Losses":0,"Name":"Duel","Points":0,"PrevRank":0,"Rank":0,"Rank_Stat_Conquest":null,"Rank_Stat_Duel":null,"Rank_Stat_Joust":null,"Season":0,"Tier":0,"Trend":0,"Wins":0,"player_id":null,"ret_msg":null},"RankedJoust":{"Leaves":0,"Losses":0,"Name":"Joust","Points":0,"PrevRank":0,"Rank":0,"Rank_Stat_Conquest":null,"Rank_Stat_Duel":null,"Rank_Stat_Joust":null,"Season":0,"Tier":0,"Trend":0,"Wins":0,"player_id":null,"ret_msg":null},"Region":"North America","TeamId":0,"Team_Name":"","Tier_Conquest":0,"Tier_Duel":0,"Tier_Joust":0,"Total_Achievements":28,"Total_Worshippers":510,"Wins":35,"ret_msg":null}]
I am using Spring Boot Java and Google's Gson library. I have looked into Jackson as well with no luck either.
I figured out the answer. The trick was to set Player to an array. For other objects I had I used a for loop to return multiple objects. For this example it is set to 0 since there is only one player.
#RequestMapping("/player")
public Player displayPlayer() throws Exception{
String player = "PacSnackz";
smite.createSession();
String test = smite.getPlayer(player);
Gson gson = new Gson();
Player[] playerObj = gson.fromJson(test, Player[].class);
return playerObj[0];
}
I have tried with gson and Jackson parsers unfortunately I couldn't achieve what I wanted to.
{
"rateName": "My Special Rate",
"adjustments": [
{
"adjustmentType": "LOAN_AMOUNT_GREATER_THAN_550K",
"rate": 0.75
},
{
"adjustmentType": "AMORTIZATION_TERM_LESS_THAN_30_YEARS",
"rate": -0.2
}
],
"errorTypes": [],
"premiumTaxs": [],
"renewalPremiums": [],
"totalInitialRate": 1.95,
"optimumPricing": false,
"miPricingVO": null,
"rateCardId": "BALS_NR",
"ratingInfoBaseRate": 1.4
}
Above is the Json I want to parse. I want to create generic methods using which I can access a value by name easily. For example:
getName(rateName) - Should return 'My Special Rate'
getNameFromArray(adjustmentType, adjustments) - Should return
'LOAN_AMOUNT_GREATER_THAN_550K'
Is there a way to do this? It should be generic so that this can be applied on any Json file.
Additional info: I tried using Gson, but this parses the whole file and throws an error if it finds an array.
JsonReader j = new JsonReader(new FileReader("Path of Json"));
j.beginObject();
while (j.hasNext()) {
String name = j.nextName();
if (name.equals("rateName")) {
System.out.println(j.nextString());
}
System.out.println(name);
}
I tried with jackson and encountered the same as Gson.
JsonFactory jfactory = new JsonFactory();
JsonParser jParser = jfactory.createJsonParser("Path of Json");
while (jParser.nextToken() != JsonToken.END_OBJECT) {
System.out.println(jParser.getCurrentName());;
}
If you mean standard library when you say generic, then org.json would be that library.
Altough not as intuitive as GSON or Jackson, it is easy to use it:
JSONObject jsonData = new JSONObject(jsonString);
String rateName= jsonData.getString("rateName");//My Special Rate
To parse array you need to loop:
JSONArray adjustments = jsonData.getJSONArray("adjustments");
for(int i = 0; i < adjustments.length(); i++){
JSONObject adjustment = adjustments.getJSONObject(i);
String adjustmentType = adjustment.getString("adjustmentType");
}
Hi You can use JASON READER , it readers the JSON and map the data into a MAP .
Below is the URL to Download the JAR JASON READER.
https://drive.google.com/open?id=0BwyOcFBoJ5pueXdadFFMS2tjLVU
Below is the example -
package com;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import com.JasonReader;
public class Test {
public static void main(String[] args) {
String request ="{\"rateName\": \"My Special Rate\",\"adjustments\":[{\"adjustmentType\": \"LOAN_AMOUNT_GREATER_THAN_550K\",\"rate\": 0.75},{\"adjustmentType\": \"AMORTIZATION_TERM_LESS_THAN_30_YEARS\",\"rate\": -0.2}],\"errorTypes\": [],\"premiumTaxs\": [],\"renewalPremiums\": [],\"totalInitialRate\": 1.95,\"optimumPricing\": false,\"miPricingVO\": null,\"rateCardId\": \"BALS_NR\",\"ratingInfoBaseRate\": 1.}";
//
Map<String,String> map =new HashMap<String,String>();
map=JasonReader.readJason(request,map);
//System.out.println(map);
for (Entry<String, String> entry : map.entrySet()) {
System.out.println(entry.getKey()+ "=" +entry.getValue());
}
}
}
OUTPUT -
rateCardId=BALS_NR
adjustments|rate1=-0.2
miPricingVO=null
adjustments|adjustmentType=LOAN_AMOUNT_GREATER_THAN_550K
adjustments|adjustmentType1=AMORTIZATION_TERM_LESS_THAN_30_YEARS
adjustments|rate=0.75
optimumPricing=false
totalInitialRate=1.95
rateName=My Special Rate
ratingInfoBaseRate=1.
You can use the standard JsonParser which is part of the javax.json package. This parser is part of Java EE since version 7 and you can use this parser without any additional library.
The parser allows you to navigate through a JSON structure using the so called 'pull parsing programming model'
JsonParser parser = Json.createParser(myJSON);
Event event = parser.next(); // START_OBJECT
event = parser.next(); // KEY_NAME
String key = parser.getString(); // 'rateName'
event = parser.next(); // STRING_VALUE
String value=parser.getString(); // 'My Special Rate'
event = parser.next(); // START_ARRAY
....
But of course you need to navigate through your json data structure
Or you can just use Jodd JSON parser. You just need to deserialize the input string and the result will be collected in regular Map and List.
JsonParser jsonParser = new JsonParser();
Map<String, Object> map = jsonParser.parse(input);
Simple as that - and the result is the most generic as it can be. Then just call map.get("rateName") to get your value and so on.
But notice that for adjustments you can get the way you want without some util method that would iterate elements and search for the right one. If you can, change the JSON so that you dont have an array of adjustments, but a map.
If you need specific results, just pass the type with the input string. See more about parsing features.
Hello i call a service if it contains multiple objects it make list but when it contain only one object it return a single object not a list [] are missing , actually i want to convert them into java class using gson but in case of single exception it throw exception but when it contain list it work fine i actually need to convert my single gSON string to array ,please help me ..here is the string
{
"response":{
"projects":{
"project":{
"ixWorkflow":1,
"sEmail":"j.a#loxvo.com",
"sPhone":"",
"ixProject":2,
"ixPersonOwner":2,
"fDeleted":false,
"sProject":"Project Default",
"fInbox":true,
"sPersonOwner":"junaid"
}
}
}
}
i want it to be like same as
{
"response":{
"projects":{
"project":[
{
"ixWorkflow":1,
"sEmail":"j.a#loxvo.com",
"sPhone":"",
"ixProject":6,
"ixPersonOwner":2,
"fDeleted":false,
"sProject":"project 2",
"fInbox":false,
"sPersonOwner":"junaid"
},
{
"ixWorkflow":1,
"sEmail":"j.a#loxvo.com",
"sPhone":"",
"ixProject":2,
"ixPersonOwner":2,
"fDeleted":false,
"sProject":"Project Default",
"fInbox":true,
"sPersonOwner":"junaid"
}
]
}
}
}
With reference to https://stackoverflow.com/a/7284813/1105291
Please try below code before you pass json to Gson for object conversion, and please let me know if you get any error. Only posibility that I can see is exception at if.
JSONObject jsonObject = new JSONObject(responseString);
JSONObject projectsJsonObject = jsonObject.getJSONObject("response").getJSONObject("projects");
if(projectsJsonObject.getJSONArray("project") == null)
{
JSONArray jsonArray = new JSONArray();
jsonArray.put(projectsJsonObject.getJSONObject("project"));
projectsJsonObject.put("project", jsonArray);
}
//Pass jsonObject to Gson
Use Google Gson
JsonParser parser = new JsonParser();
JsonObject o = (JsonObject)parser.parse("{\"a\": \"A\"}");
I have a jersey client that is getting JSON from a source that I need to get into properly formatted JSON:
My JSON String looks like the folllowing when grabbing it via http request:
{
"properties": [
{
someproperty: "aproperty",
set of data: {
keyA: "SomeValueA",
keyB: "SomeValueB",
keyC: "SomeValueC"
}
}
]
}
I am having problems because the json has to be properly formatted and keyA, keB, and keyC are not surrounded in quotes. Is there some library that helps add quotes or some best way to go about turning this string to properly formatted json? Or if there is some easy way to convert this to a json object without writing a bunch of classes with variables and lists that match the incoming structure?
you can use json-lib. it's very convenient! you can construct your json string like this:
JSONObject dataSet = new JSONObject();
dataSet.put("keyA", "SomeValueA") ;
dataSet.put("keyB", "SomeValueB") ;
dataSet.put("keyC", "SomeValueC") ;
JSONObject someProperty = new JSONObject();
dataSet.put("someproperty", "aproperty") ;
JSONArray properties = new JSONArray();
properties.add(dataSet);
properties.add(someProperty);
and of course you can get your JSON String simply by calling properties.toString()
I like Flexjson, and using lots of initilizers:
public static void main(String[] args) {
Map<String, Object> object = new HashMap<String, Object>() {
{
put("properties", new Object[] { new HashMap<String, Object>() {
{
put("someproperty", "aproperty");
put("set of dada", new HashMap<String, Object>() {
{
put("keyA", "SomeValueA");
put("keyB", "SomeValueB");
put("keyC", "SomeValueC");
}
});
}
} });
}
};
JSONSerializer json = new JSONSerializer();
json.prettyPrint(true);
System.out.println(json.deepSerialize(object));
}
results in:
{
"properties": [
{
"someproperty": "aproperty",
"set of dada": {
"keyA": "SomeValueA",
"keyB": "SomeValueB",
"keyC": "SomeValueC"
}
}
]
}
Your string isn't JSON. It's something that bears a resemblance to JSON. There is no form of JSON that makes those quotes optional. AFAIK, there is no library that will reads your string and cope with the missing quotes and then spit it back out correctly. You need to find the code that produced this and repair it to produce actual JSON.
You can use argo, a simple JSON parser and generator in Java