test.cs

public IActionResult View(string id) {

  // retrieve document by id and return document as model
  using (var db = new LiteDatabase("App_Data/MyData.db")) {

      var fs = db.FileStorage;

      using (MemoryStream ms = new MemoryStream()) {
          fs.Download("$/documents/dummy_" + id + ".tx", ms);
          var fileBytes = ms.ToArray();

          ViewDocument viewDoc = new ViewDocument() {
              Name = "dummy" + id + ".tx",
              BinaryData = Convert.ToBase64String(fileBytes)
          };

          return View(viewDoc);
      }
  }
}