Java 8 Nashorm engine not able to fetch key from json object

Question

I am trying to store a JSON object in nashorn engine and fetch value by key.

ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
engine.put("minimumBet", "{\"SEK\":\"1\",\"EUR\":\"2\"}");

//This prints {"SEK":"1","EUR":"2"}
System.out.println(engine.eval("minimumBet")); 

//This assert fails
//engine.eval("minimumBet['SEK']") is retruning null
assertEquals(1, engine.eval("minimumBet['SEK']"));

Please tell me what am I missing.

Answer 1

engine.put("minimumBet", "{\"SEK\":\"1\",\"EUR\":\"2\"}"); does not evaluate the value you place in the property, so you are just setting a string. You would need to eval the string inside the engine.

import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class Test {
    public static void main(String[] args) {
        try {
            ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
            engine.put("minimumBet", "{\"SEK\":1,\"EUR\":2}");
            engine.eval("var bet = JSON.parse(minimumBet);");
            engine.eval("var krona = bet['SEK'];");
            engine.eval("var euro = bet['EUR'];");
            Object krona = engine.get("krona");
            Object euro = engine.get("euro");
            System.out.println(krona + " " + krona.getClass());
            System.out.println(euro + " " + euro.getClass());
        } catch (ScriptException ex) {
            ex.printStackTrace();
        }
    }
}

Yields:

1 class java.lang.Integer
2 class java.lang.Integer