C# EF只是第一次编辑我的实体

我有一个WCF Rest服务，如您所见：

 [OperationContract]
        [WebInvoke(Method = "PUT", UriTemplate = "/EditNews", RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json)]
        bool Edit(News entity);

 News student = new News
            {
                Id = Guid.Parse("7320D87D-4819-4663-BCF9-2D09F9E4BD70"),
                Subject = "aaaaaaaaaaaaaassssssssssss",
                ViewerCounter = 3, // removed the "" (string)
                MainContent = "fsdsd", // renamed from "Content"
                SubmitDateTime = DateTime.Now,
                ModifiedDateTime = DateTime.Now,
                PublisherName = "sdaadasd",
                PictureAddress = "adfafsd",
                TypeOfNews = "bbbbb"
            };
            WebClient Proxy1 = new WebClient();
            Proxy1.Headers["Content-type"] = "application/json";
            MemoryStream ms = new MemoryStream();
            DataContractJsonSerializer serializerToUplaod = new DataContractJsonSerializer(typeof(News));
            serializerToUplaod.WriteObject(ms, student);
            byte[] a = Proxy1.UploadData("http://localhost:47026/NewsRepository.svc/EditNews", "PUT", ms.ToArray());

使用此代码：

public class NewsRepository :INewsRepository
    {
        private readonly DataContext _ctx;
        public NewsRepository(DataContext ctx)
        {
            _ctx = ctx;

        }

        public bool Add(News entity)
        {
            try
            {
                _ctx.News.Add(entity);
                _ctx.SaveChanges();
                return true;
            }
            catch (Exception ex)
            {
                // TODO log this error
                return false;
            }
        }

        public bool Edit(News entity)
        {
            try
            {

                _ctx.Entry(entity).State = System.Data.Entity.EntityState.Modified;
                _ctx.SaveChanges();
                return true;
            }
            catch (Exception ex)
            {
                // TODO log this error
                return false;
            }
        }
}}

因此，我在我的客户机中调用我的服务来编辑我的实体，如您所见：

 [OperationContract]
        [WebInvoke(Method = "PUT", UriTemplate = "/EditNews", RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json)]
        bool Edit(News entity);

 News student = new News
            {
                Id = Guid.Parse("7320D87D-4819-4663-BCF9-2D09F9E4BD70"),
                Subject = "aaaaaaaaaaaaaassssssssssss",
                ViewerCounter = 3, // removed the "" (string)
                MainContent = "fsdsd", // renamed from "Content"
                SubmitDateTime = DateTime.Now,
                ModifiedDateTime = DateTime.Now,
                PublisherName = "sdaadasd",
                PictureAddress = "adfafsd",
                TypeOfNews = "bbbbb"
            };
            WebClient Proxy1 = new WebClient();
            Proxy1.Headers["Content-type"] = "application/json";
            MemoryStream ms = new MemoryStream();
            DataContractJsonSerializer serializerToUplaod = new DataContractJsonSerializer(typeof(News));
            serializerToUplaod.WriteObject(ms, student);
            byte[] a = Proxy1.UploadData("http://localhost:47026/NewsRepository.svc/EditNews", "PUT", ms.ToArray());

因此，我运行我的服务和客户端应用程序，点击编辑按钮，我的编辑工作。但这是我第二次在编辑方法中遇到这个错误

---

确保没有任何其他实体附加到您的新闻模型，可能它正试图添加一个附加到您的新闻实体的实体，只需传递它而不包含任何子对象，并确保在选择此实体时使用了AsNoTracking

最终解决方案

  public bool Edit(News entity)
            {
                try
                {
                    News Edited = _ctx.News.Where(i => i.Id == entity.Id).First();
                    _ctx.Entry(Edited).CurrentValues.SetValues(entity);
                    _ctx.SaveChanges();
                    return true;
                }
                catch (Exception ex)
                {
                    // TODO log this error
                    return false;
                }
            }

---

没有。我只是对wcf REST发送的新闻有一个距离。我的意思是在编辑期间是否附加了任何导航属性，如果没有，请在get上选择时检查AsNoTracking。您可以详细告诉我如何使用AsNoTracking来避免此错误吗？在编辑对象之前，请调用数据库以获取该对象。那个调用，确保上次我遇到这个错误时，它变成了我忘记添加asnotracking它可能被缓存在您的上下文中，这就是为什么当您使用asnotracking时它不会被缓存，所以它会知道它是被修改的同一项