Unity instance not saved between scripts

Question

I have a script Planet.cs like :

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[System.Serializable]
public class Planet : MonoBehaviour
{
    public string Name { get; set; } 
}

In a custom function I need to generate multiple planets, so I create a new GameObject, I add the component Planet (my script), and I set My attribute like :

        GameObject planet2 = GameObject.CreatePrimitive(PrimitiveType.Sphere);
        planet2.AddComponent<Planet>();

        Planet planetCompo2 = planet2.GetComponent<Planet>();
        planetCompo2.Name = "Planet 2";

If I check in the end of my function, all attributes are setted, If I check the attribute Name of any planets it's ok.

My problem is, in another script, I try to get a Planet from a GameObject with component Planet, but I always have a null Object.

Example : this.gameObject.GetComponent<Planet>() or this.GetComponent<Planet>() are always null where this is the GameObject with Planet Component.

Why my instances are not saved ? What my error ? Thanks !

In the "another script", are you sure the planet is already instantiated before calling GetComponent ? Nothing wrong in your code, probably a script loading order problem. — FLX
– FLX, Commented Mar 8, 2017 at 13:58
Yes, in the another script, The GameObject "this" is the GameObject clicked in my scene, so he is real :) A script loading order problem ? — Clément Andraud
– Clément Andraud, Commented Mar 8, 2017 at 13:59
waitwaitwait. Something strange with what you think "this" is — FLX
– FLX, Commented Mar 8, 2017 at 14:02

Programmer · Accepted Answer · 2017-03-08 14:30:29Z

4

this.gameObject.GetComponent<Planet>() and this.GetComponent<Planet>() are both the-same thing since they will both try to get the Planet component from the this GameObject this script is attached to.

The thing to look at for here is this. You are referring to this script. When you do that from another script, you are trying to the Planet component from this script that is executing the GetComponent function. If this script does not have the Planet component, you get null. I am sure this is what's happening.

I would suggest naming the GameObject you just created:

GameObject planet2 = GameObject.CreatePrimitive(PrimitiveType.Sphere);
planet2.AddComponent<Planet>();
//Name it
planet2.name = "Your Other GameObject";

Now, find the GameObject from another script then access the Planet component from it:

GameObject obj = GameObject.Find("Your Other GameObject");
//Now you can do 
Planet planetCompo2 = obj.GetComponent<Planet>();

Since you already have the variable Name in your Planet script, you can all Planet script with GetComponent[s] then just loop through it and check which one has the name "Planet 2".

Planet planetCompo2 = null;

//Get all Planet components
Planet[] tempComPlanet = GetComponents<Planet>();

//Seatch for which one has the name "Planet 2"
for (int i = 0; i < tempComPlanet.Length; i++)
{
    if (tempComPlanet[i].Name == "Planet 2")
    {
        //Found. Store it to planetCompo2 then exit the loop
        planetCompo2 = tempComPlanet[i];
        break;
    }
}

edited Mar 8, 2017 at 14:30

answered Mar 8, 2017 at 13:59

Programmer

126k22 gold badges253 silver badges344 bronze badges

Sign up to request clarification or add additional context in comments.

8 Comments

Chad Over a year ago

Does the GameObject.Find("someStringHere") find an object by it's name in the editor? And what happens if there are multiple entities with the same name?

Programmer Over a year ago

"Does the GameObject.Find("someStringHere") find an object by it's name in the editor?" Yes. "And what happens if there are multiple entities with the same name?" It finds the first one only. If you plan to use it make sure that your object names are unique. If two objects have the-same name but under different objects then you can use "/" to find it as a folder name which is cool. For example, two Door Objects under different Objects: GameObject.Find("House/Door"); and GameObject.Find("Car/Door");

Clément Andraud Over a year ago

I think I have another thing, I'm working on a Clone on the real GameObject Planet. Is this a problem ? Do the clone either copy the instance of the component Planet ?

Clément Andraud Over a year ago

Planet clonePlanet = GameObject.Instantiate(My_Original_planet, GameObject.Find("SolarSystem").transform);

Clément Andraud Over a year ago

Yeah, I know now it's not a good solution :) Thanks for help I will think about that ;)

|

Chad · Accepted Answer · 2017-03-08 14:12:19Z

1

Using the keyword 'this' in your other script will reference that object looking for a Planet script attached to it. You should either look for the Game Object that has the script attached or instantiate one.

Apply a tag like PlanetObject to your game object with the planet script and use something like the following:

var planet = GameObject.FindWithTag("PlanetObject").GetComponent<Planet>();

edited Mar 8, 2017 at 14:12

answered Mar 8, 2017 at 13:59

Chad

8928 silver badges24 bronze badges

Collectives™ on Stack Overflow

Unity instance not saved between scripts

2 Answers 2

8 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

8 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related