CODEWITHSUNDEEP
c#unity-game-enginejson.net
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Reputation: 730

Referencing an object inside another object causes JsonSerializationException

I am new to Unity/C# and having difficulty converting two objects into JSON.

The goal is to build a JSON object that looks as follows:

{
    "operation": "pin",
    "question": {
        "studentPin": "123456"
    }
}

In Java I would simply do the following:

Question question = new Question();
question.setStudentPin(pin);
ServerRequest request = new ServerRequest();
request.setOperation(Constants.PIN_OPERATION);
//set the values entered for the pin entered
request.setQuestion(question);

String json = gson.toJson(request);

However, when I do the following in C#

 //Creating a new Question object
 Question question = new Question();
 question.studentPin = pinNumber.text;
 ServerRequest request = new ServerRequest();
 request.operation = Constants.PIN_OPERATION;
 //set the values entered for the pin entered
 request.question = question;

 string json = JsonConvert.SerializeObject(request);

I get the following error:

JsonSerializationException: Self referencing loop detected for property 'question' with type 'Question'.Path

I have googled this error and understand that this usually happens when in your model classes there is a reference back to a parent object and that parent object has a reference back to its child object, which causes a circular reference during serialization.

However, I am unsure how exactly I can go about resolving these issues.

My Question class is set-up as follows:

public class Question : MonoBehaviour {

    public string studentPin;

}

My ServerRequest class is set-up as follows:

public class ServerRequest : MonoBehaviour {

    public string operation;
    public Question question;


}

Any help or guidance would be greatly appreciated.

Upvotes: 0

Views: 243

Answers (2)

Lincoln Cheng
Lincoln Cheng

Reputation: 2303

  1. Consider using JsonUtility.ToJson() instead.
  2. If Question and ServerRequest are mainly used to store data only, consider not subclassing it from MonoBehaviour.

In all:

[System.Serializable]
public class Question {
    public string studentPin;
}

[System.Serializable]
public class ServerRequest {
    public string operation;
    public Question question;
}

//Do your instantiation, setups, etc as above.
string json = JsonUtility.ToJson(request);

Read more about Unity's serialization here.

Upvotes: 1

Akos Nagy
Akos Nagy

Reputation: 4360

You should use the JsonSerializaerSettings class and setup reference-based serialization:

 JsonSerializerSettings settings = new JsonSerializerSettings
 {
    PreserveReferencesHandling = PreserveReferencesHandling.All,
    ReferenceLoopHandling = ReferenceLoopHandling.Serialize
 };

 string json = JsonConvert.SerializeObject(request, settings);

Upvotes: 0

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