Nested data classes are not parsed back correctly

[yooneskh]

These are my models

data class IChapter<T>(
  var _id: String,
  var title: String,
  var picture: T,
  var createdAt: Long,
  var updatedAt: Long
)

data class IMedia(
  var _id: String,
  var name: String,
  var extension: String,
  var path: String,
  var size: Long,
  var createdAt: Long,
  var updatedAt: Long
)

I want to save this in prefrences.

object prefs : PreferenceHolder() {
  var chapters: List<IChapter<IMedia>> by bindToPreferenceField(listOf())
}

After i populate it with objects coming from this

    fun getRemoteChapters(): List<IChapter<IMedia>> = listOf(
      IChapter("1", "در تنهایی و ...", IMedia("1", "f1", "jpg", "https://images.all-free-download.com/images/wallpapers_large/small_island_wallpaper_beaches_nature_wallpaper_1388.jpg", 0, 0, 0), 0, 0),
      IChapter("2", "پیش از جکومت", IMedia("2", "f2", "jpg", "https://besthqwallpapers.com/Uploads/22-11-2017/29941/thumb2-sea-landscape-waves-beach-sand-clouds.jpg", 0, 0, 0), 0, 0),
      IChapter("3", "تا رهایی", IMedia("3", "f3", "jpg", "https://earthporm.com/wp-content/uploads/2014/08/small-man-grand-nature-landscape-photography-62.jpg", 0, 0, 0), 0, 0)
    )

If i close and open my app i get class cast error as below

    java.lang.ClassCastException: com.google.gson.internal.LinkedTreeMap cannot be cast to ir.yooneskh.alisotries.database.models.IMedia

Am i doing anything wrong?

[MarcinMoskala]

Not sure. This is GSON working on here. Try to use fromJson and toJson and look at how does this works.