C＃实体框架更新SaveChanges（）未更新数据库条目

Question

现在正在研究这个C＃Entity Framework更新问题。也许你们中的一个人可以看到我所缺少的东西。

问题出在代码的userEntry部分内。我已经跟踪并确保userEntry确实填充了我打算更新的信息。调用entities.SaveChanges();时，数据库中的记录不会更新。

            int userId;
            using (Entities entities = new Entities())
            {
                MSIFeedStoreData feedStoreEntry = entities.MSIFeedStoreDatas
                    .FirstOrDefault((d) => d.Alias == user.Alias);

                if (Object.ReferenceEquals(feedStoreEntry, null))
                {
                    throw new ArgumentException("The user's alias could not be located in the feed store. The user cannot be added at this time.");
                }

                int feedStorePersonnelIdValue;
                if (Int32.TryParse(feedStoreEntry.PersonellID, out feedStorePersonnelIdValue))
                {
                    user.EmployeeId = feedStorePersonnelIdValue;
                }
                else
                {
                    throw new ApplicationException("DATABASE BUG CHECK: An entry was found in the feed store for this user but the personnel ID could not be parsed.");
                }

                MSIUser userEntry = entities.MSIUsers
                    .FirstOrDefault((u) => u.EmployeeID == feedStorePersonnelIdValue);

                if (Object.ReferenceEquals(userEntry, null))
                {
                    userEntry = Mapper.Map<MSIUser>(user);
                    userEntry = entities.MSIUsers.Add(userEntry);
                }
                else
                {
                    Mapper.DynamicMap<User, MSIUser>(user, userEntry);
                    entities.MSIUsers.Attach(userEntry);
                }

                userId = userEntry.MSIUser_ID;
                entities.SaveChanges();
            }

            return userId;
        }

Answer 1

删除对Attach的调用，该调用已附加到上下文。