We need to evaluate JSON object expressions in java.

We have the following source JSON object

{
  "a": 100,
  "b": 200,
  "c": 300,
  "d": "calc(a c)",
  "f": {
    "g": 100,
    "h": 200,
    "i": "calc(g h)"
  }
}

we need output this format

{
  "a": 100,
  "b": 200,
  "c": 300,
  "d": 400,
   "f": {
    "g": 100,
    "h": 200,
    "i": 300
  }
}

We tried

we tried https://github.com/octomix/josson but that is more of a filtering JSON.

CodePudding user response：

Hope this helps. All the necessary information is mentioned inside the code itself.

import java.util.Iterator;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.json.JSONObject;

public class Main {

    public static void main(String[] args) {

        String inputString = "{'a': 100, 'b': 200, 'c': 300, 'd': 'calc(a c)', 'f': {'g': 100, 'h': 200, 'i': 'calc(g h)'} }";

        JSONObject newJSON = parseJSONValue(inputString, new JSONObject());

        System.out.println(newJSON.toString());
        // {"a":100,"b":200,"c":300,"d":400,"f":{"g":100,"h":200,"i":300}}

    }

    public static JSONObject parseJSONValue(String inputString, JSONObject resultJSON) {

        // Parse your string as JSONObject
        JSONObject jsonObject = new JSONObject(inputString);
        Iterator<String> keys = jsonObject.keys();

        // Iterate through your keys
        while (keys.hasNext()) {

            String key = keys.next();
            Object value = jsonObject.get(key);

            if (value instanceof Integer) {

                // Your normal values

            } else if (value instanceof String) {

                // Your 'calc(x y)' strings

                // Extract everything between "(" and ")" from calc(a c)
                Pattern pattern = Pattern.compile("\\((.*?)\\)");
                Matcher m = pattern.matcher(value.toString());

                while (m.find()) {

                    // a c
                    String evalString = m.group(1);

                    // Split by ' '
                    String[] splitEvalString = evalString.split("\\ ");

                    // Check if exactly 2 values are found
                    if (splitEvalString.length == 2) {
                        value = (Integer) jsonObject.get(splitEvalString[0])
                                  (Integer) jsonObject.get(splitEvalString[1]);
                    }

                }

            } else if (value instanceof JSONObject) {
                // Your nested JSONObjects
                // Recursively call this method
                value = parseJSONValue(value.toString(), new JSONObject());
            }

            // Add to your new JSON Object
            resultJSON.put(key, value);

        }

        return resultJSON;

    }

}

CodePudding user response：

Josson josson = Josson.fromJsonString(jsonString);
JsonNode node = josson.getNode("field(d:eval(d), f.field(i:eval(i)))");
System.out.println(node.toPrettyString());

Output

{
  "a" : 100,
  "b" : 200,
  "c" : 300,
  "d" : 400.0,
  "f" : {
    "g" : 100,
    "h" : 200,
    "i" : 300.0
  }
}