How to check the class_name type of the root node of a PackedScene?

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1

Godot Version

4.3

Question

I implemented a spawner class that is supposed to spawn mobs in a level in my game. One of the exported variables is the PackedScene to be spawned by the spawner. I also wanted to add a check whether the set PackedScene is of a certain type, so the users would get a warning icon in their editor if they set the wrong PackedScene. In order to do that, I need to get information on the class_name type of the script of the root node of the PackedScene which I would then want to check if it extends my Mob class_name.
Is there a good general way to do this?

I’ve tried using the packed_scene.get_state().get_node_type(0) but that returns the native type (e.g. CharacterBody2D) not the type of the script attached to the node.

I also tried using groups and packed_scene.get_state().get_node_groups(0), but that doesn’t work for scenes that inherited the Mob scene., in which case I need to use packed_scene.get_state().get_node_instance(0).get_state().get_node_groups(0). Now, I can work with this option for now, but it feels quite hacky. Is there a better way to do this?

2

In the latest version of Godot this is available.

https://www.reddit.com/r/godot/comments/1ahqgfv/comment/kopxvs0/

Prior versions you had to do a hack like setting a var in your class_name

If curious Google it some more.

3

@wyattbiker While that’s good to know, I don’t know how I would get the script of the root node in the PackedScene (at least not without instancing it, which I don’t want to do here). Would you happen to know how I can do that?
If so, then this would be the complete solution.

4

Try this. First line gets the top node in your scene. Second line gets the script. If no class_name then it gets the top node of scene name:

	# Get top scene node
	var current_scene=get_tree().get_current_scene()
	# Get script attached to it
	var o_script=current_scene.get_script()
	# Get the class_name r if nill get node name
	var s_class_name:StringName=o_script.get_global_name()
	print(s_class_name)
5

But if you have to instance the scene then you only need to add an ID string property with the name or ostensibly, just do a type check if my_scene_instance is MyClass.

(the way I read it) OP is asking how to tell if the scene is the desired type when a user drags a scene into the export variable (inside a tool script).
It doesn’t seem possible without instancing it at least once.

6

@wyattbiker
@sancho2 is correct. I’m talking about the case when I don’t have a scene instance, but a PackedScene set by the user in editor and I’d like to do a check before I do any instancing.