Get Length of JSON Array

Question

I am using UnityWebRequest to get a query and parse it in JSON. Everything works as expected but here the node users is an array that is defined as below:

{
  "data": {
    "users": [
      {
        "id": "981d8432-c423-46e1-9124-5b5f111bd749",
      },
      {
        "id": "11cd2db5-3e6e-4363-b8e5-afd2a67a5333",
      }
   ]
}

Now I know that the array is 2 values but how do I make the for loop detect it by the length? Such that

using SimpleJSON;
...
...
void Start()
{

  JSONNode itemsData = JSON.Parse (request.downloadHandler.text);
  for(int i = 0;i<(LengthOfUsers); i++)
    {
      Debug.Log("\nIDs: "+ itemsData["data"]["users"][i]["id"]);
    }
}

You could use [`JsonUtility.FromJson`](https://docs.unity3d.com/ScriptReference/JsonUtility.FromJson.html) where `T` would be a type which represents thr structure of your json-data. This way you get typesafe access to the content of your json-data. — Ackdari, Oct 06 '20 at 13:07
Does this answer your question? [Get Length of array JSON.Net](https://stackoverflow.com/questions/19025174/get-length-of-array-json-net) — code11, Oct 06 '20 at 13:36

Athanasios Kataras · Accepted Answer · 2020-10-06T13:12:57.757

2

Seems like JSonNode implements IEnumerator: https://wiki.unity3d.com/index.php/SimpleJSON

That means that you could in theory use the Linq extentions like this:

itemsData["data"]["users"].Count

edited Oct 06 '20 at 13:12

answered Oct 06 '20 at 13:04

Athanasios Kataras

25,191
4
32
61

I am getting an error that ```'JSONNode.Count' cannot be used like a method.``` So is there an alternate way to do this? – Amar.linsila Oct 06 '20 at 13:11
Try without the parenthesis `()`. There is an implemenation with a member that gets the count from the internal list. – Athanasios Kataras Oct 06 '20 at 13:13

score 0 · Answer 2 · answered Oct 06 '20 at 13:13

itemsData["data"]["users"].Length should do the trick in your case.

If you want, you could make your user-list into a variable:

JSONNode itemsData = JSON.Parse(request.downloadHandler.text);
var users = itemsData["data"]["users"]
for(int i = 0; i < (users.Length); i++)
{
    Debug.Log("\nIDs: "+ users[i]["id"]);
}

An alternative is to not worry about the length, by using a foreach:

JSONNode itemsData = JSON.Parse(request.downloadHandler.text);
foreach(var user in itemsData["data"]["users"])
{
    Debug.Log("\nIDs: "+ user["id"]);
}

itemsData["data"]["users"].Length did not work as it was throwing an error as it cannot be used as a method. — Amar.linsila, Oct 06 '20 at 13:20

score 0 · Answer 3 · answered Oct 06 '20 at 13:18

0

Thanks to Athanasios Kataras for the guidance. Instead of JSONNode, I used just simple var and then counted the length of the array users. The whole code is given below:

var parseJSON = JSON.Parse (request.downloadHandler.text);
var Count = parseJSON["data"]["users"].Count;
  for(int i = 0;i<Count; i++)
    {
      Debug.Log("\nIDs: "+ itemsData["data"]["users"][i]["id"]);
    }
}

answered Oct 06 '20 at 13:18

Amar.linsila

273
1
2
13

You can see my answer for an idiomatic way of deserializing in Unity using standard Unity API. – Eduard Hasanaj Oct 06 '20 at 13:31

score 0 · Answer 4 · answered Oct 06 '20 at 13:28

You can use JsonUtility provided by Unity. In order to deserialize above schema you need following classes

[System.Serializable]
public class User
{
    public string ID { get { return id; } }

    [SerializeField] private string id;
}

[System.Serializable]
public class UserCollection
{
    public User[] users;
}

JsonUtility.FromJson<UserCollection>(jsonText);

In the model class I suggest you to encapsulate attributes behind getters because sometimes we may need to deal with json that contains "_" or not idiomatic naming for c# class attributes and JsonUtility does not support custom attributes you are force to place weird names in the class.

Get Length of JSON Array

4 Answers4