Unable to convert Json string to Map<String, Object>

Question

I am trying to convert my json into a map uisng jackson-core-2.9.6 . My json is

 {
  "name": "Loren",
  "inputDetails": {
  "truncated": false,
   "result": [
     {
    "subjects": [
      {
        "math": "50",
        "SST": "37 ",
        "status": "ACTIVE"
      }
    ]
  }
]
},
"timeoutInSeconds": null
}

and the Java Code is by which I am trying to parse this JSON into Map is like this

public static void main(String[]args){
    
    String request="{\r\n  \"name\": \"Loren\",\r\n  \"inputDetails\": {\r\n    \"truncated\": false,\r\n    \"result\": [\r\n      {\r\n        \"subjects\": [\r\n          {\r\n            \"math\": \"50\",\r\n            \"SST\": \"37 \",\r\n            \"status\": \"ACTIVE\"\r\n          }\r\n        ]\r\n      }\r\n    ]\r\n  },\r\n  \"timeoutInSeconds\": null\r\n}";
    try {  
            List servicesResponse = null;
            Map<String,Object> inputParam=null;
            ObjectMapper objectMapper = new ObjectMapper();
            request =  objectMapper.writeValueAsString(request);
            objectMapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);
            objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
            objectMapper.enable(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT);
            inputParam = (Map<String, Object>) objectMapper.readValue(request, Map.class);
            servicesResponse = (List)inputParam.get("result");
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    
  }

Exception which I am getting is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of java.util.LinkedHashMap (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('{ "name": "Loren", "inputDetails": { "truncated": false, "result": [ { "subjects": [ { "math": "50", "SST": "37 ", "status": "ACTIVE" } ] } ] }, "timeoutInSeconds": null }') at [Source: (String)""{\r\n "name": "Loren",\r\n "inputDetails": {\r\n "truncated": false,\r\n "result": [\r\n {\r\n "subjects": [\r\n {\r\n "math": "50",\r\n "SST": "37 ",\r\n "status": "ACTIVE"\r\n }\r\n ]\r\n }\r\n ]\r\n },\r\n "timeoutInSeconds": null\r\n}""; line: 1, column: 1] at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:63) at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1342) at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1031) at com.fasterxml.jackson.databind.deser.ValueInstantiator._createFromStringFallbacks(ValueInstantiator.java:371) at com.fasterxml.jackson.databind.deser.std.StdValueInstantiator.createFromString(StdValueInstantiator.java:323) at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:357) at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:29) at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4013) at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3004) at Test.main(Test.java:22)

I have tried looking into similar questions available on Stakoverflow but unable to find json with similar structure which is having both string and objects.

Answer 1

This is what causing your problem

request = objectMapper.writeValueAsString(request);

It affects your String json, just pass the String object to the readValue method, it accepts also strings

Answer 2

The above code worked for me for parsing. But since you need result variable, it is inside inputDetails. So you need to change last line as below:

List servicesResponse = (List) ((Map<String, Object>)inputParam.get("inputDetails")).get("result");