FolderListResource.gd

extends Resource
class_name FolderListResource

export (String) onready var FolderPath setget set_folder_path
export (String) var ResourceCategory

var all_resources = []

func set_folder_path(value):
    FolderPath = value
    load_all_resources()

func load_all_resources() -> void:
    var folder = Directory.new()
    if FolderPath and folder.open(FolderPath) == OK:
        folder.list_dir_begin()
        
        var file_name = folder.get_next()
        while file_name != "":
            if not folder.current_is_dir() and file_name.find(".tres") != -1:
                all_resources.push_back(load(FolderPath.plus_file(file_name)))
            
            file_name = folder.get_next()
            
        folder.list_dir_end()
    else:
        print("An error occurred when trying to access the folder.")
        
        
func find_index_of(resource : Resource) -> int:
    return all_resources.find(resource)


The 4.0 version of this is:

extends Resource
class_name FolderListResource

@export
@onready var FolderPath : String:
    set(value):
        FolderPath = value
        load_all_resources()
        
@export
var ResourceCategory : String

var all_resources = []

func load_all_resources() -> void:
    if FolderPath:
        var folder = DirAccess.open(FolderPath)
        folder.list_dir_begin()
        
        var file_name = folder.get_next()
        while file_name != "":
            if not folder.current_is_dir() and file_name.find(".gd") == -1:
                all_resources.push_back(load(FolderPath.path_join(file_name)))
            
            file_name = folder.get_next()
            
        folder.list_dir_end()
    else:
        print("An error occurred when trying to access the folder.")
        
        
func find_index_of(resource : Resource) -> int:
    return all_resources.find(resource)

This is one of the more useful resources I've ever created. This will automatically load all resources within a given folder. These can be images, sounds, text files, .tres files - anything you want. Just be careful as they are not guaranteed to all be the same type unless you're very careful!