DataStageEditor.cs

using UnityEngine;
using UnityEditor;

[CanEditMultipleObjects]
[CustomEditor(typeof(DataStage))]
public class DataStageEditor : Editor {
    public override void OnInspectorGUI()
    {
        // Get this Stage-Data
        DataStage dataStage = target as DataStage;

        // Find "Stage" Object in Hierarchy-Window
        var stageObject = GameObject.Find("Stage");

        // Get Objects with Stage-Components("Item", Enemy", etc) in "Stage" Object
        var items      = stageObject.GetComponentsInChildren<StageItem>();
        var characters = stageObject.GetComponentsInChildren<StageCharacter>();

        if(GUILayout.Button("Save")){
            // Overwrite Item-Data (Scriptable Object)
            dataStage.items = new DataItem[items.Length];
            for(int i=0; i<items.Length; i++){
                dataStage.items[i] = new DataItem();
                dataStage.items[i].name = items[i].gameObject.name;
                dataStage.items[i].localPosition = items[i].transform.localPosition;
                dataStage.items[i].localRotation = items[i].transform.localRotation;
                dataStage.items[i].localScale = items[i].transform.localScale;
                // and more Item-Component unique params
            }

            // Overwrite Enemy-Data (Scriptable Object)
            dataStage.characters = new DataCharacter[characters.Length];
            for(int i=0; i<characters.Length; i++){
                dataStage.characters[i] = new DataCharacter();
                dataStage.characters[i].name = characters[i].gameObject.name;
                dataStage.characters[i].localPosition = characters[i].transform.localPosition;
                dataStage.characters[i].localRotation = characters[i].transform.localRotation;
                dataStage.characters[i].localScale = characters[i].transform.localScale;
                // and more Enemy-Component unique params
            }
        }

        if(GUILayout.Button("Load")){
            // Clear Stage-Objects in Hierarchy
            for(int i=items.Length-1; i>=0; i--)
                DestroyImmediate(items[i].gameObject);
            for(int i=characters.Length-1; i>=0; i--)
                DestroyImmediate(characters[i].gameObject);

            // Instantiate Stage-Enemies
            for(int i=0; i<dataStage.characters.Length; i++){
                var obj = Instantiate(Resources.Load("StageObject/Character")) as GameObject;
                obj.name = dataStage.characters[i].name;
                obj.transform.SetParent(stageObject.transform);
                obj.transform.localPosition = dataStage.characters[i].localPosition;
                obj.transform.localRotation = dataStage.characters[i].localRotation;
                obj.transform.localScale = dataStage.characters[i].localScale;
            }

            // Instantiate Stage-Items
            for(int i=0; i<dataStage.items.Length; i++){
                var obj = Instantiate(Resources.Load("StageObject/Item")) as GameObject;
                obj.name = dataStage.items[i].name;
                obj.transform.SetParent(stageObject.transform);
                obj.transform.localPosition = dataStage.items[i].localPosition;
                obj.transform.localRotation = dataStage.items[i].localRotation;
                obj.transform.localScale = dataStage.items[i].localScale;
            }
        }

        DrawDefaultInspector();
    }
}