Adding material to object programmatically raises MissingComponentException-CodePudding

I'm pretty new to Unity, I'm sure it's a stupid question, I'm trying to add a Material to a GameObject, here's my code:

// this works
GameObject cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
Renderer rend = cube.GetComponent<Renderer>();
rend.material = this.material;

// this does not work
GameObject obj1 = Resources.Load($"{basePath}/{this.componentName}") as GameObject;
Renderer rend2 = obj1.GetComponent<Renderer>();
rend2.material = this.material;
Instantiate(obj1, position, Quaternion.identity);

// this does not work too
GameObject obj2 = Resources.Load($"{basePath}/{this.componentName}") as GameObject;
GameObject instatiatedObj = Instantiate(obj2, position, Quaternion.identity);
Renderer rend3 = instatiatedObj.GetComponent<Renderer>();
rend3.material = this.material;

As I wrote in comment adding the material to a cube works, when I'm trying to add it to a loaded game object does not work, in both cases objects are displayed correctly but without material. In Unity the following error is displayed:

MissingComponentException: There is no 'Renderer' attached to the "xxx" game object, but a script is trying to access it.
You probably need to add a Renderer to the game object "xxx". Or your script needs to check if the component is attached before using it.

Thanks in advance.

CodePudding user response：

When you are instantiating an .obj you are not instantiating a single GameObject. When looking at the hierachy you will see the name of the .obj and a default object.
See:

In that case the default object will contain the objects MeshRenderer component. You have to change your code to use GetComponentInChildren (Documentation).

GameObject obj1 = Resources.Load($"{basePath}/{this.componentName}") as GameObject;
Renderer rend2 = obj1.GetComponentInChildren<Renderer>();
rend2.material = this.material;
Instantiate(obj1, position, Quaternion.identity);