SceneField

SceneField.cs

// Taken from http://wiki.unity3d.com/index.php/SceneField

using UnityEngine;

[System.Serializable]
public class SceneField : ISerializationCallbackReceiver
{
  public string SceneName => sceneName;
  public string ScenePath => scenePath;

#if UNITY_EDITOR
  public UnityEditor.SceneAsset sceneAsset;
#endif

#pragma warning disable 414
  [SerializeField] private string sceneName = "";
  [SerializeField] private string scenePath = "";
#pragma warning restore 414


  // Makes it work with the existing Unity methods (LoadLevel/LoadScene)
  public static implicit operator string(SceneField sceneField)
  {
#if UNITY_EDITOR
    return System.IO.Path.GetFileNameWithoutExtension(UnityEditor.AssetDatabase.GetAssetPath(sceneField.sceneAsset));
#else
    return sceneField.sceneName;
#endif
  }

#if UNITY_EDITOR
  public void EditorSetScene(UnityEngine.SceneManagement.Scene scene)
  {
    sceneAsset = UnityEditor.AssetDatabase.LoadAssetAtPath<UnityEditor.SceneAsset>(scene.path);
    sceneName = System.IO.Path.GetFileName(scene.path);
    scenePath = scene.path;
  }
#endif

  public void OnBeforeSerialize()
  {
#if UNITY_EDITOR
    sceneName = this;
    scenePath = UnityEditor.AssetDatabase.GetAssetPath(sceneAsset);
#endif
  }
  public void OnAfterDeserialize() { }
}

Here is a cleaned up version with Odin that gets rid of the extra inspector fields.

using Sirenix.OdinInspector;
using UnityEngine;

// Taken from http://wiki.unity3d.com/index.php/SceneField
    [InlineProperty]
    [System.Serializable]
    public class SceneField : ISerializationCallbackReceiver {
        public string SceneName => _sceneName;
        public string ScenePath => _scenePath;

#if UNITY_EDITOR
        [HideLabel]
        public UnityEditor.SceneAsset _sceneAsset;
#endif

#pragma warning disable 414
        [HideInEditorMode]
        [ReadOnly]
        [SerializeField]
        private string _sceneName = "";

        [HideInEditorMode]
        [ReadOnly]
        [SerializeField]
        private string _scenePath = "";
#pragma warning restore 414


        // Makes it work with the existing Unity methods (LoadLevel/LoadScene)
        public static implicit operator string (SceneField sceneField) {
#if UNITY_EDITOR
            return System.IO.Path.GetFileNameWithoutExtension(
                UnityEditor.AssetDatabase.GetAssetPath(sceneField._sceneAsset)
            );
#else
    return sceneField.SceneName;
#endif
        }

#if UNITY_EDITOR
        public void EditorSetScene (UnityEngine.SceneManagement.Scene scene) {
            _sceneAsset = UnityEditor.AssetDatabase.LoadAssetAtPath<UnityEditor.SceneAsset>(scene.path);
            _sceneName = System.IO.Path.GetFileName(scene.path);
            _scenePath = scene.path;
        }
#endif

        public void OnBeforeSerialize () {
#if UNITY_EDITOR
            _sceneName = this;
            _scenePath = UnityEditor.AssetDatabase.GetAssetPath(_sceneAsset);
#endif
        }

        public void OnAfterDeserialize () {
        }
    }