Parse jsonObject when field names are unknowm

Question

I'm trying to extract some data from a JsonObject. The problem is that the fields that come inside that json have unpredictable names.

How can I extract that information having this weird field names?

Here is an example:

 "myObject":{  
          "216cfa89a2de57554b36b177f0bfbb05":{  

           },
           "0cf9182b5ceba2cb64174141a13e647d":{  

           },
           "eb1d1b19e117ba1387a798d9194b4660":{  

           },
           "157b52871e8e560c7ec0be111ef02363":{  

           },
           "4db69dd3a8ae8e0089bd2959ab0c5f86":{  

           },
}

I'm using gson, where we have the method getAsJsonObject, but how can I use it if I don't know the field names?

JsonObject jsonObject= myObjectJsonObject.getAsJsonObject("???");

Also, there can be a variable number of fields, and this is a problem too. I wonder why I don't get an jsonArray as a response, it would be more suitable and I could have parse it that way.

it's content changes, the name of the fields and their number is variable — Jones, Nov 11 '15 at 09:05

score 1 · Answer 1 · answered Nov 11 '15 at 09:22

In your case its beter to use JsonPath

With JSON like this :

{
  "myObject": {
    "216cfa89a2de57554b36b177f0bfbb05": {
      "field1": true
    },
    "0cf9182b5ceba2cb64174141a13e647d": {
      "field2": true
    },
    "eb1d1b19e117ba1387a798d9194b4660": {
      "field3": true
    },
    "157b52871e8e560c7ec0be111ef02363": {
      "field2": true
    },
    "4db69dd3a8ae8e0089bd2959ab0c5f86": {
      "field5": true
    }
  }
}

And an expretion of JsonPth

$.myObject.*

You will get an array of fields

[
  {
    "field1": true
  },
  {
    "field2": true
  },
  {
    "field3": true
  },
  {
    "field2": true
  },
  {
    "field5": true
  }
]

Hope that help :)

Michael Lloyd Lee mlk · Accepted Answer · 2015-11-11T10:12:27.613

Use the JsonObject.entrySet().

    String json = "{ 'abcd': { 'a':'d' }, 'dcba': { 'd':'a' } }";
    JsonObject o = new JsonParser().parse(json).getAsJsonObject();

    for(Map.Entry<String, JsonElement> entry : o.entrySet()) {
        System.out.println(entry.getKey());
        System.out.println(entry.getValue());
    }

Or you could get a map when you load the object:

    Map<String, JsonObject> map = new Gson().fromJson(json, new TypeToken<Map<String, JsonObject>>(){}.getType());
    for(Map.Entry e : map.entrySet()) {
        System.out.println(e.getKey());
        System.out.println(e.getValue());
    }
}

Or you could add a JsonDeserializer which can deserialize your class into something sensible (likely a map).

score -1 · Answer 3 · edited May 23 '17 at 10:30

-1

If you look at this post you see that you can simply do:

Object o = new Gson().fromJson(json, Object.class);

The object returned is a Map of String and either String or a Map.

edited May 23 '17 at 10:30

Community

1
1

answered Nov 11 '15 at 09:05

Jelle van Es

613
6
20

score -1 · Answer 4 · answered Nov 11 '15 at 09:50

-1

JsonObject o = new JsonParser().parse("some json string").getAsJsonObject();

answered Nov 11 '15 at 09:50

Muzaffer

1,457
1
13
22

While this code block may answer the OP's question, this answer would be much more useful if you explain how and why this code is different from the code in the question, and why that solves the problem without introducing others. – Mifeet Nov 11 '15 at 10:39
Please consider editing your post to add more explanation about what your code does and why it will solve the problem. An answer that mostly just contains code (even if it's working) usually wont help the OP to understand their problem. – SuperBiasedMan Nov 11 '15 at 11:33

Parse jsonObject when field names are unknowm

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