NullReference Error after Instantiating a Prefab

Unity Engine
1

So I don´t know if I´m missing an dumb error of myself but my problem is:
I´ve got an class which deserializes a json file into a tree-structure. That part is working without an error. Now while doing this i want to create Objects of another class - we just call it “CityObject” for the moment.

public class CityObject : MonoBehaviour {

    private GameObject gameObject;

    public ArrayList children;

    public int width;


    public CityObject(GameObject prefab, int newWidth)
    {
        gameObject = Instantiate(prefab);
        children = new ArrayList();
        width = newWidth;
    }
}

Depending on the Information in the json file, the GameObject should get a simple cube prefab or a flat cube prefab and instantiate it. So far so good - in the unity Scene all Objects are created, so in my example there are 5 created GameObjects - 2 flat and 3 simple cubes.

public class CityBuilder : MonoBehaviour {

    public GameObject plane;
    public GameObject cube;
    public CityObject origin;

    private int maxW = 0;

    private ProjectView ProcessProjectData(string jsonString)
    {
        ProjectView parsejson = JsonUtility.FromJson<ProjectView>(jsonString);
        return parsejson;
    }

    private GameObject FindPrefab(string type)
    {
        switch (type.ToLower())
        {
            case "block": newPlane = false; return cube;
            case "scope": newPlane = true; return plane;
            default: return null;
        }
    }
   
    private CityObject CreateGameObjectFromProjectData(ProjectData projectData, CityObject cityObjectParent)
    {
     
        var prefab = FindPrefab(projectData.type);
        if (!prefab)
            return null;


        CityObject rootCityObject = new CityObject(prefab,  getSubtreeWidth(projectData));

       
        if(maxW == 0)
        {
            maxW = rootCityObject.width;
        }
        scaleObject(rootCityObject);
       
        /* * *
         * If an object has one or more children, then the children should execute this method on their own.
         */

        if (projectData.children != null)
        {
            foreach (ProjectData data in projectData.children)
            {
                Debug.Log(data.id);
            }
            foreach (ProjectData data in projectData.children)
            {
                CityObject newChild = CreateGameObjectFromProjectData(data, rootCityObject);
                rootCityObject.appendChild(newChild);
            }
        }
        return rootCityObject;
    }

The problem is that in line 40 i want to scale the gameObject of the cityObject like this:

private void scaleObject(CityObject node)
{
float scaleRatio = (float)(node.width/maxW);
node.gameObject.transform.localScale.Set(scaleRatio, scaleRatio, scaleRatio);
}

Then there is a NullReference Error for the node.GameObject - so there seems to be no reference between the cityObject and the GameObject. This is the part i can´t understand. Is it the Instantiate in the CityObejct Constructor? Isn´t the Instantiate creating a Reference between the “Script-Object” and the Gameobject in the unity-Scence?

2

Nevermind, I was wrong. Sorry :smiley: