C# 列表到 JToken

Question

如何将对象列表保存在 json 文件中？这是我的代码：

string json = System.IO.File.ReadAllText(Server.MapPath("~/settings.conf"));
            dynamic jsonObj = JsonConvert.DeserializeObject(json);

City city = svm.City;
            jsonObj["city"]["name"] = city.Name;
            jsonObj["city"]["latitude"] = city.Latitude;
            jsonObj["city"]["longitude"] = city.Longitude;
            jsonObj["city"]["id"] = city.ID;
List<Social> bottomSocial = svm.BottomSocials;
            jsonObj["bottomSocial"] = bottomSocial;


            string output = JsonConvert.SerializeObject(jsonObj, Newtonsoft.Json.Formatting.Indented);
            System.IO.File.WriteAllText(Server.MapPath("~/settings.conf"), output);

它适用于 City，但不适用于 bottomSocial。