Jython: Parse JSON object to get value (object has array) - java

I have JavaScript that parses a JSON object (object has array) and returns the value from the ZONE field.
var obj = JSON.parse(json_text);
parsed_val = obj.features[0].attributes.ZONE
I would like to convert the JavaScript code to Jython.
This is what I've tried:
from com.ibm.json.java import JSONObject
obj = JSONObject.parse(json_text)
parsed_val = obj.get('features.attributes.ZONE');
The Jython compiles, but it doesn't return a valid value (it returns None). I think this is because I haven't referenced the array properly.
How can I parse the JSON object/array using Jython to get the ZONE value?
(Jython version is 2.7.0. However, I can't seem to use Python's JSON library (normally included in Jython)).

I needed to use get() at each level of the object.
As well as specify the array's index position after the first level: [0].
from com.ibm.json.java import JSONObject
obj = JSONObject.parse(json_text)
parsed_val = obj.get("features")[0].get("attributes").get("WEEK")
Credit goes to #vikarjramun for pointing me in the right direction. Thanks.

Related

Getting a JSON Array from JSON Object (SOLVED)

First time having to work with JSON data on my own, even if very simple.
Here is the JSON data I'm working with:
{
"heart" : [92, 108],
"temperature" : [85.08, 85.66],
"conductance" : [4095, 4095]
}
What I'm attempting to do is extract one of the three arrays found within that JSON object, but I'm receiving a JSONException: Not a primitive array: class org.json.JSONArray. Here is a portion of the code that I'm using to extract the array of values associated with "heart":
JSONObject obj = new JSONObject(obtainJSONObject());
JSONArray arr = new JSONArray(obj.getJSONArray("heart")); // This is where the error is occuring
int low = arr.getInt(0);
int high = arr.getInt(1);
I've tried to follow what this solution answered, but can't really make much sense of it: How to Get JSON Array Within JSON Object?
I'm not sure if it has something to do with the way how the JSON data is being formatted? I did check online to see if it was any valid or not at https://jsonformatter.curiousconcept.com/. Any help or insights will be greatly appreciated!

Can't get value from JSONObject

So I am using the simple json library to perform some json operations. Right now I can construct a JSONObject from a json string but I am not able to get the value from the object I created.
For example if I do something like:
String value = (String) jsonRecord.get("Key");
I will get an error saying:
java.lang.ClassCastException: org.json.simple.JSONObject cannot be cast to java.lang.String
I removed the type cast to string and it works in IntelliJ. However, when I do this at command line it gives me an error saying:
error: incompatible types: Object cannot be converted to String
The schema is as follows:
{
"myArray": {
"array": ["Decaf mocha", "Vanilla mocha", "Chai Latte"]
},
"Item": {
"string": "Decaf macha"
}
}
Update: the toString() fixed the problem. But when I tried to get the array I am getting:
java.lang.ClassCastException: org.json.simple.JSONObject cannot be cast to org.json.simple.JSONArray
Can someone please suggest how to fix the problem? Thanks!
Your value is a JSONObject, not a string. Your error message makes that quite clear. If you really want it as a string, use
String value = jsonRecord.get("Key").toString();
You can pass any object to System.out.println, not just strings, but to actually turn it to a string, you need to call toString() yourself.
However, if you're expecting an actual String as the Key, and not a JSONObject, then you should take a second look at your JSON, because you're doing something wrong.
UPDATE:
Okay, looking at your schema, I see the problem. Instead of mapping the keys to values directly, your JSON maps keys to objects which then contain values. So to get the array in the JSON you posted, instead of
value = jsonRecord.get("myArray")
you would use
JSONArray value = jsonRecord.getJSONObject("myArray").getJSONArray("array");
and for the string, you would use
String value = jsonRecord.getJSONObject("Item").getString("string");
Just need to add the current "org.json" dependency would resolve your issue as latest version holds get() method (JSONObject class) which returns Object.
Below is my maven dependency:-
<dependency>
<groupId>org.json</groupId>
<artifactId>json</artifactId>
<version>20190722</version>
</dependency>
Below is my code which performs get key operation.
public void iterateJsonObject(JSONObject jsonObj) {
jsonObj.keySet().forEach(keyStr ->
{
Object keyvalue = jsonObj.get(keyStr);
System.out.println("key: "+ keyStr + " value: " + keyvalue);
});
}
You can prevent the ClassCastException by using Generics, because Generics provide compile time checks and can be used to develop type-safe applications.
You are not converting the json record value that you are fetching into a string.
String value = String.valueOf(jsonRecord.get("Key"));
his should fix your problem. You can also use toString() method but I personally prefer String.valueOf() over it because at times toString() tends to give garbage value.

How to parse a jsonObject or Array in Java

I have an API request from my CRM that can either return a jsonObject if there is only one result, or a jsonArray if there are multiple results. Here are what they look like in JSON Viewer
JsonObject:
JsonArray:
Before you answer, this is not my design, it's my CRM's design, I don't have any control over it, and yes, I don't like how it is designed either. The only reason I am not storing the records in my own database and just parsing that, which would be MUCH easier, is because my account is having issues not running some workflows that would allow me to auto add the records. Is there any way to figure out if the result is an object or an array using java? This is for an android app by the way, I need it to display the records on the phone.
You should use OPT command instead of GET
JSONObject potentialObject=response.getJsonObject("resuslt")
.getJsonObject("Potentials");
// here use opt. if the object is null, it means its not the type you specified
JSONObject row=potentialObject.optJsonObject("row");
if(row==null){
// row is json array .
JSONArray rowArray=potentialObject.getJsonArray("row");
// do whatever you like with rowArray
} else {
// row is json object. do whatever you like with it
}
ONE
You can use instanceof keyword to check the instances as in
if(json instanceof JSONObject){
System.out.println("object");
}else
System.out.println("array");
TWO
BUT I think a better way to do this is choose to use only JSONArray so that the format of your results can be predicated and catered for. JSONArrays can contain JSONObjects. That is they can cover the scope of JSONObject.
For example when you get the response (either in a JSONObject or a JSONArray), you need to store that in an instance. What instance are you going to store it in? So to avoid issues use JSONArray to store the response and provide statements to handle that.
THREE
Also you can try method overloading in java or Generics
Simplest way is to use Moshi, so that you dont have to parse, even in the case of the Model changing later, you have to change your pojo and it will work.
Here is the snippet from readme
String json = ...;
Moshi moshi = new Moshi.Builder().build();
JsonAdapter<BlackjackHand> jsonAdapter = moshi.adapter(BlackjackHand.class);
BlackjackHand blackjackHand = jsonAdapter.fromJson(json);
System.out.println(blackjackHand);
https://github.com/square/moshi/blob/master/README.md

Converting JSONObject to JSON using GSON

I am having an Java Object which consist many type of variables including a JSONObject.
Whan i debug my object i got the following String for JSONObject:-
{"INCLUSIONS":{"OPTIONS":[{"display":"Complimentary stay for children under 5 without extra bed"}]}}
But when i used:-gson.toJson(JSONObj),I got following
{"myHashMap":{"INCLUSIONS":{"myHashMap":{"OPTIONS":{"myArrayList":[{"myHashMap":{"display":"Complimentary stay for children under 5 without extra bed"}}]}}}}}
Someone please can elaborate why it is converting JSONObject to Map & list ??
Or Any work Around ??
Thanks.
Just use myJsonObj.toString() instead of myJsonObj.toJSON()
Your problem happens because a JSONObject is stored as a HashMap to allow the programmer to reach values with methods based on keys. As example,
String jsonStr = "{'key': 'value'}";
JsonObject json = gson.fromJson(jsonStr, JsonObject.class);
String value = json.get("key").getAsString();
You can figure that json attributes are stored as a HashMap<JsonElement>

Detect type of JSON attribute

JSON:
{"attribute1":11, "attribute2":"string atribute"}
I want to detect what kind of type are attribute1 and attribute2:
attribute1 is integer
attribute2 is string
jsonObject.getAttributeType("attribute2"); // should output: string/integer/boolean.
It was very easy to achieve in PHP or OBJC. Suggestions?
(I'm assuming that the Android for the org.json package is that same as you can find on the json.org site ... here.)
The only method on a JSONObject that will give you the underlying value ... without coercing it ... is JSONObject.get(name). If name is known, the result is the object that represents the value internally. I haven't done a comprehensive trawl of the code, but I think it can only be one of the following types:
Boolean, Long, Double, String, JSONArray, JSONObject
You should be able to discriminate these using instanceof.
But should be asking yourself if this is the right thing to do. The normal way to deal with JSON object attributes via the JSONObject API is to use the methods that coerce them into the type that you expect. In most cases, it doesn't matter if a number is sent as 42 or 42.0 or "42" ... and it is best not to be picky if the intent is easy to determine.
Another solution you can use the jackson library to do this,
import com.fasterxml.jackson.databind.JsonNode;
import com.github.fge.jackson.JsonLoader;
//Defining the JSON object
JSON json = {"attribute1":11, "attribute2":"string atribute"};
//Get the needed attribute
String value = json.get("attribute1");
//Convert the attribute to JsonNode
JsonNode value = JsonLoader.fromString(value);
//Then you can check type as below
value.isObject();
value.isArray();
value.isDouble();
value.isTextual();
value.isInt()

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