Ef包括未更新的鏈接表

我有這個 ef 方法，我正在使用它并使用IdInclude選擇父表。我正在發送一個要創建到資料庫中的模型。它對于我發送一個新記錄的作業正常，但是當我發送一個已經有記錄的值時，我希望它更新資料而不是創建新記錄。我還需要更改其他內容才能使更新正常作業嗎？SingleMeetingPollingId0MeetingPollingQuestionId

public ResultStatus SaveMeetingPollingQuestion(Model.MeetingPollingQuestion mpq)
        {
            using (var db = new NccnEcommerceEntities())
            {
                using (DbContextTransaction dbTran = db.Database.BeginTransaction())
                {

                    ResultStatus result = new ResultStatus();

                    try
                    {


                        var meetingPolling = db.MeetingPollings
                            .Include(x => x.MeetingPollingQuestions)
                            .Include(x => x.MeetingPollingQuestions.Select(q => q.MeetingPollingParts))
                                .Single(x => x.MeetingPollingId == mpq.MeetingPollingId);

                        var newMeetingPollingQuestion = new EFModel.MeetingPollingQuestion
                        {
                            MeetingPollingQuestionId = mpq.MeetingPollingQuestionId,
                            MeetingPollingId = mpq.MeetingPollingId,
                            MeetingPollingQuestionTypeId = mpq.MeetingPollingQuestionTypeId,
                            SequenceOrder = mpq.SequenceOrder,
                            MeetingPollingParts = mpq.MeetingPollingParts.Select(p => new EFModel.MeetingPollingPart
                            {
                                MeetingPollingPartsTypeId = p.MeetingPollingPartsTypeId,
                                MeetingPollingPartsValues = p.MeetingPollingPartsValues.Select(v => new EFModel.MeetingPollingPartsValue
                                {
                                    QuestionValue = v.QuestionValue,
                                    MeetingPollingPartsValuesTypeId = v.MeetingPollingPartsValuesTypeId
                                }).ToList()
                            }).ToList()
                        };

                        meetingPolling.MeetingPollingQuestions.Add(newMeetingPollingQuestion);

                        db.SaveChanges();
                        dbTran.Commit();

                        result.ResultCode = Convert.ToInt32(Enums.Result.Code.Success);
                        result.Message = "Successfully uploaded.";
                    }
                    catch (Exception e)
                    {
                        dbTran.Rollback();
                        result.Message = "Error Save Meeting Polling Question"   e.Message;
                        result.ResultCode = Convert.ToInt32(Enums.Result.Code.Error);

                    }
                    return result;
                }
            }
        }

uj5u.com熱心網友回復：

您要求的是物體框架不支持“開箱即用”的“Upsert” 。其他查詢語言（如 PostgreSQL 等）支持 Upsert。

您將不得不使用物體框架“滾動您自己的”Upsert 功能。由于您使用的是 . Add()在您的示例中，您只是插入資料，但從不更新它。為此，您需要檢查問題 ID 是否已存在。

你可以做類似的事情......

// determine whether the question id exists
var mpqIdExists = db.MeetingPollings.Where(mp => mp.MeetingPollingId == mpq.MeetingPollingId && mp.MeetingPollingQuestionId == mpq.MeetingPollingQuestionId).Any();

if (mpqIdExists) 
{
     // update
     db.Entry(newMeetingPollingQuestion).State = EntityState.Modified;
}
else 
{
     // insert
     meetingPolling.MeetingPollingQuestions.Add(newMeetingPollingQuestion);
}

db.SaveChanges();
dbTran.Commit();

禮貌： 使用 EF6 執行 UPSERT 的更有效方式

標籤：C＃实体框架

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