JsonUtility and Arrays [Error - "JSON must represent an object type"]

Question

Hi all,

I know this has been asked previously and I have looked through those post. I am having a hard time wrapping my brain around what I have to do to get an array to work with the JsonUtitlity Serialization, or if it's even possible.

Heres what I have:

 [System.Serializable]
     public class JSONObject : System.Object  {
         public string[] values;
     }
 
     public void request (params string[] values){
         JSONObject JSON = new JSONObject ();
         JSON.values = values;
         StartCoroutine(webCoro(JsonUtility.ToJson(JSON)));
     }
 
     void response (string JSONstring) {
         JSONObject JSON = JsonUtility.FromJson <JSONObject> (JSONstring);
     }
     
     IEnumerator webCoro (string data){
         string URL = "http://" + host + ":" + port;
         WWW request = new WWW (URL, encoding.GetBytes (data));
         while (!request.isDone) {
             yield return null;
         }
         Debug.Log ("Request Error: " + request.error);
         response (request.text);
     }
 
     public void test (){
         request ("script", "action", "test"); 
     }

When I run test () I get:

ArgumentException: JSON must represent an object type. UnityEngine.JsonUtility.FromJson[JSONObject] (System.String json) (at C:/buildslave/unity/build/artifacts/generated/common/modules/JSONSerialize/JsonUtilityBindings.gen.cs:24) Web.response (System.String JSONstring) (at Assets/Web.cs:36) Web+c__Iterator0.MoveNext () (at Assets/Web.cs:50)

What do I need to do to make this happen?

Thanks in advance, Sean

Answer 1

Best Answer

Answer by Bunny83 · Feb 29, 2016 at 01:02 PM

Well, how does your JSON data looks like? The deserializer expects something like this:

 { "values":["one","two","three"]}

How does your data look like? Is it just an array? The JsonUtility seems to only work with objects as root element. If your data looks like this:

 ["one","two","three"]

You might want to wrap it manually in an object like this:

 string yourJSONArray;
 string JSONToParse = "{\"values\":" + yourJSONArray + "}";

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STBarnard · Feb 29, 2016 at 04:23 PM 0

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So ultimately the answer was that my node.js code was using JSON.stringify (myRequest) on a request that was already in JSON format giving me :

"{\"values\":[\"script\",\"action\",\"test\"]}"

So when I cut that out I received a response more to the tune of:

{"values":["script","action","test"]}

And this worked out, thanks everyone for your responses, they helped me come to this conclusion.

Sean

kryzodoze · Sep 17, 2017 at 04:04 AM 0

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Thank you Bunny83, this is exactly what I needed.

Answer 2

Answer by STBarnard · Feb 29, 2016 at 01:11 PM

Had my node server echo some data back.

"{\"values\":[\"script\",\"action\",\"test\"]}"

That's what i'm working with.

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flashframe · Feb 29, 2016 at 02:27 PM 1

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I just tested your code without the WWW request, and it seems to serialise the array fine.

The string should look like this: {"values”:[“script”,”action”,”test”]}

Did you see this answer? http://answers.unity3d.com/questions/844423/wwwtext-not-reading-utf-8-text.html

STBarnard flashframe · Feb 29, 2016 at 04:15 PM 0

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I tried this based off that post:

 IEnumerator webCoro (string data){
         string URL = "http://" + host + ":" + port;
         WWW request = new WWW (URL, encoding.GetBytes (data));
         while (!request.isDone) {
             yield return null;
         }
         Debug.Log ("Request Error: " + request.error);
         string responseString = System.Text.Encoding.UTF8.GetString(request.bytes, 3, request.bytes.Length - 3);
         Debug.Log (responseString);
         response (responseString);
     }

It just cut off the opening brackets:

"values\":[\"script\",\"action\",\"test\"]}"

JsonUtility and Arrays [Error - "JSON must represent an object type"]

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