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Extract data from YouTube Data API with Java / Sprint Boot

I am trying to extract title, videoId, and description data of all the videos I got from using YT Data API. I was able to return the data in what looks like JSON format (but it is actually LinkedHashMap when I check with getClass()) in Postman and Chrome browser, but was unable to extract the value from specific keys I have mentioned above.
I tried:
System.out.println((rest.getForObject(url, Object.class, params)).get("items"));
It asks me to cast to JSONObject
Overall, I need to extract the data and convert into xml before sending it over to ActiveMQ
Edit:
Format I get in Postman/Chrome browser
{
"kind": "youtube#searchListResponse",
"etag": "3LV4enCWAzOaiqJb_cMIUVklXJY",
"nextPageToken": "CAUQAA",
"regionCode": "CA",
"pageInfo": {
"totalResults": 478712,
"resultsPerPage": 5
},
"items": [
{
"kind": "youtube#searchResult",
"etag": "gt6x7J2XpzU8Mpb3yv9_HmNTzWY",
"id": {
"kind": "youtube#video",
"videoId": "I_ZK0t9-llo"
},
"snippet": {
"publishedAt": "2021-03-01T18:15:13Z",
"channelId": "UC2WHjPDvbE6O328n17ZGcfg",
"title": "Stack Overflow is full of idiots.",
"description": "The Stack Overflow culture needs to be fixed. The overall gatekeeping & elitism in computer science & programming - as a whole ...",
"thumbnails": {
"default": {
"url": "https://i.ytimg.com/vi/I_ZK0t9-llo/default.jpg",
"width": 120,
"height": 90
},
"medium": {
"url": "https://i.ytimg.com/vi/I_ZK0t9-llo/mqdefault.jpg",
"width": 320,
"height": 180
},
"high": {
"url": "https://i.ytimg.com/vi/I_ZK0t9-llo/hqdefault.jpg",
"width": 480,
"height": 360
}
},
"channelTitle": "ForrestKnight",
"liveBroadcastContent": "none",
"publishTime": "2021-03-01T18:15:13Z"
}
},
{
"kind": "youtube#searchResult",
"etag": "RwmGP1qMzUCzK6oV82s0NUEOETw",
"id": {
"kind": "youtube#video",
"videoId": "sMIslcynm0Q"
},
"snippet": {
"publishedAt": "2021-03-07T16:00:13Z",
"channelId": "UCXwjZTvpFiBl93ACCUh1NXQ",
"title": "How To Use Stack Overflow (no, ForrestKnight, it's not full of idiots)",
"description": "Hey everyone, I can't believe I have to make this video. Unfortunately ForrestKnight recently made a video saying Stack Overflow ...",
"thumbnails": {
...
Edit2: I tried
JSONObject jsonObject = new JSONObject( rest.getForObject(url, Object.class, params));
JSONArray array = jsonObject.getJSONArray("items" );
for(int i=0;i<array.length();i++){
JSONObject snippet =array.getJSONObject(i);
System.out.println(snippet.getJSONObject("snippet").get("title"));
}
JSONObject["items"] not found.
Edit3:
I also tried without Edit2 and just
JSONObject jsonObject = new JSONObject( rest.getForObject(url, Object.class, params));
System.out.println(jsonObject);
No error and I was about to fetch data shown in Postman. But in console printed {}, meaning I might not have gotten the data and won't be able to extract.
I tried extracting using .get System.out.println(jsonObject.get("items"));
and I got the same error JSONObject["items"] not found.
Seems like it could be a format error, again it looks like json already and to use .get, I placed it inside jsonObject but found nothing
Edit4: I can confirm the data I get back is Json (like it says on the doc) using
try {
new JSONObject(rest.getForObject(url, Object.class, params));
} catch (JSONException ex) {
// edited, to include #Arthur's comment
// e.g. in case JSONArray is valid as well...
try {
new JSONArray(rest.getForObject(url, Object.class, params));
} catch (JSONException ex1) {
return false;
}
}
return true;
Returned true
Edit5: Seems like the keys is null after trying
String[] keys = JSONObject.getNames(jsonObject);
// iterate over them
for (String key1 : keys) {
// retrieve the values
Object value = jsonObject.get(key1);
// if you just have strings:
String value1 = (String) jsonObject.get(key1);
System.out.println(value);
System.out.println(value1);
}
Cannot read the array length because "keys" is null

The RestTemplate delegates to the underlying Jackson to deserialize the JSON string to a java object .If you get the HTTP response as a generic object type , it will deserialize it into a Map.
You can simply create a POJO with the structure that is the same as the expected JSON response, and then use the Jackson annotations to configure how to deserialize the JSON into this POJO , and get the HTTP response as this POJO class.
Something like :
public class Result {
#JsonProperty("items")
private List<Item> items = new ArrayList<>();
}
public class Item {
#JsonProperty("kind")
private String kind;
#JsonProperty("etag")
private String etag;
#JsonProperty("snippet")
private List<Snippet> snippets = new ArrayList<>();
}
public class Snippet {
#JsonProperty("channelId")
private String channelId;
#JsonProperty("title")
private String title;
}
Then use the following to get the response :
Result result = rest.getForObject(url, Result.class, params);
Once you get the Result POJO , use the favourite library to serialize it into XML.
P.S I just show you the ideas. You have to fine tune the POJO structure

Getting Error while converting from JSON String Java Model Class

I am have a problem in converting JSON String to Java object. As per my scenario Database (PostgreSQL) is returning JSON String in PGOBJECT through function.
Which I am trying to convert into model Class. Returned value JSON sample is:
{
"A_REASON": [
{
"cd": "CLOSE",
"name": "CLOSE",
"value": "A_REASON",
"type": "A_REASON"
}
],
"P_MODE": [
{
"cd": "CLOSE",
"name": "CLOSE",
"value": "A_REASON",
"type": "A_REASON"
}
],
"F_TYPE": [
{
"cd": "CLOSE",
"name": "CLOSE",
"value": "A_REASON",
"type": "A_REASON"
} ] }
I have created My Model Classes like below.
public class MODEL {
private List<MISCDTO> A_REASON;
private List<MISCDTO> P_MODE;
private List<MISCDTO> F_TYPE;
//settter and Getter
}
public class MISCDTO{
private String cd;
private String name;
private String value;
private String type;
}
When I am trying to convert into Model Class from JSON String it gives error, I have tried multiple ways
ObjectMapper mapper = new ObjectMapper();
MODEL object = mapper.readValue(pGobject.getValue(), MODEL.class);
List<MODEL> list = mapper.readValue(pGobject.getValue(), new TypeReference<List<MODEL >>(){});
MODEL object= mapper.readValue(pGobject.getValue(), new TypeReference<MODEL>() {});
I am looking to convert into either Map> or MODEL object having List, List etc. Please help. Please do help in Formatting as i am trying to Write in Stack Standard. Still novice on this.

Spring RestTemplate parse JSON object with variable keyname

I have a REST API call that returns the following JSON object. I need to parse this with Spring's RestTemplate. The problem is that the first key ISBN:0132856204 is variable (the numbers change depending on the book). How would I go about doing this?
{
"ISBN:0132856204": {
"publishers": [
{
"name": "Pearson"
}
],
"pagination": "xxiv, 862p",
"identifiers": {
"isbn_13": [
"978-0-13-285620-1"
],
"openlibrary": [
"OL25617855M"
]
},
"weight": "1340 grams",
"title": "Computer networking",
"url": "https://openlibrary.org/books/OL25617855M/Computer_networking",
"number_of_pages": 862,
"cover": {
"small": "https://covers.openlibrary.org/b/id/7290810-S.jpg",
"large": "https://covers.openlibrary.org/b/id/7290810-L.jpg",
"medium": "https://covers.openlibrary.org/b/id/7290810-M.jpg"
},
"publish_date": "2013",
"key": "/books/OL25617855M",
"authors": [
{
"url": "https://openlibrary.org/authors/OL31244A/James_F._Kurose",
"name": "James F. Kurose"
},
{
"url": "https://openlibrary.org/authors/OL658909A/Keith_W._Ross",
"name": "Keith W. Ross"
}
],
"subtitle": "A Top-Down Approach"
}
}

In here "ISBN:0132856204" is a value and also a key for your business.
To get ISBN first, what about wrapping json content with 1 more closure?
{
"yourAwesomePlaceHolderKey" :
{
"ISBN:0132856204": {
......
}
}
}
First get the ISBN key as a value, then your ISBN value can be used as a key to get related content.
First goal will be extracting -String1,Object1- pair where String1 is "yourAwesomePlaceholderKey" and second goal will be again extracting -String2,Object2- from Object1 where String2 is your ISBN key.

This is the way I solved it, using JsonPath for getting the book out of the JSON object and Jackson for mapping it to a Book object:
RestTemplate restTemplate = new RestTemplate();
String isbn = "0132856204";
String endpoint = "https://openlibrary.org/api/books?jscmd=data&format=json&bibkeys=ISBN:{isbn}";
//Get JSON as String
String jsonString = restTemplate.getForObject(endpoint, String.class, isbn);
//Configure JsonPath to use Jackson for mapping
Configuration.setDefaults(new Configuration.Defaults() {
private final JsonProvider jsonProvider = new JacksonJsonProvider();
private final MappingProvider mappingProvider = new JacksonMappingProvider();
#Override
public JsonProvider jsonProvider() {
return jsonProvider;
}
#Override
public MappingProvider mappingProvider() {
return mappingProvider;
}
#Override
public Set<Option> options() {
return EnumSet.noneOf(Option.class);
}
});
//Parse the JSON as a book
Book book = JsonPath.parse(jsonString).read("$.ISBN:" + isbn, Book.class);

You can use JsonProperty to solve
#JsonProperty("ISBN:0132856204")

Jackson - ReadValue fails

UPDATE! Fixed, there was a missed public statement on prices attribute that was the reason this error occurred.
I am trying out Jackson for converting between .json files and objects. However, I keep receiving this error "UnrecognizedPropertyException: Unrecognized field "Prices" (class imp.JsonDTO), not marked as ignorable (one known property: "Ticker"]" .
I am trying to convert a json file that looks like this:
{
"Ticker": "AAPL",
"Prices": [
{
"Date": "1986-01-02T00:00:00",
"Value": 22.25,
"Action": "Sell"
},
{
"Date": "1986-01-03T00:00:00",
"Value": 22.38,
"Action": "Buy"
},
{
"Date": "1986-01-06T00:00:00",
"Value": 22.38,
"Action": "Sell"
}
]
}
I am converting like this:
ObjectMapper mapper = new ObjectMapper();
File file = new File("INTC.json");
JsonDTO dto = mapper.readValue(file, JsonDTO.class);
DTO's that I am using:
public class JsonDTO {
public String Ticker;
List<PriceDTO> Prices = new ArrayList<PriceDTO>();
}
and..
public class PriceDTO {
public String Date;
public double Value;
public String Action;
}
Tried a few different ways for "Prices" but seem unable to get it right.Thanks for help :)

Gson help with parse array - works without array but won't with array

Can somebody help me with Gson parser. When I remove change from JSON and Result it works fine but with change it throws JsonParseException-Parse failed.
Result[] response = gson.fromJson(fileData.toString(), Result[].class);
I have classes like this
public class Result {
public String start_time;
public String end_time;
public change[] change;
}
and
public class change {
public String id;
public String name;
}
and Json string like
[
{
"start_time": "8:00",
"end_time": "10:00",
"change": [
{
"id": "1",
"name": "Sam"
},
{
"id": "2",
"name": "John"
}
]
},
{
"start_time": "9:00",
"end_time": "15:00",
"change": [
{
"id": "1",
"name": "Sam"
},
{
"id": "2",
"name": "John"
}
]
}
]
Can somebody tell me what I did wrong ? Any idea why it won't work with array ?

As has been suggested, you need to use a list instead. Gson has pretty good documentation for using parametized types with the parser, you can read more about it here. Your code will end up looking like this:
Type listType = new TypeToken<List<Result>>() {}.getType();
List<Result> results = gson.fromJson(reader, listType);
for (Result r : results) {
System.out.println(r);
}