实体框架出错:AcceptChanges无法继续,因为对象的键值与ObjectStateManager中的另一个对象冲突

Question

我遇到了Entity Framework 4.0的问题.我正在尝试保存一个"处理"对象,该对象具有"段"对象的集合.每当我尝试添加/编辑一个我在添加2个或更多新段的处理对象时,我会收到以下错误:

已成功提交对数据库的更改,但更新对象上下文时发生错误.ObjectContext可能处于不一致状态.内部异常消息:AcceptChanges无法继续,因为对象的键值与ObjectStateManager中的另一个对象冲突.在调用AcceptChanges之前,请确保键值是唯一的.

这是我正在使用的保存方法."SegmentID"列是"Segment"的PK,它是一个在DB中设置为自动递增的整数(MS SQL 2008).默认情况下,"SegmentID"设置为0,直到从DB获取更新的段.

public bool Save(Treatment myTreatment)
    {
        bool result = false;


        using (tamcEntities db = new tamcEntities())
        {
            // IF NEW TREATMENT, CREATE IT AND ADD TO DB
            if (myTreatment.Treatment_ID == 0)
            {

                db.Treatments.AddObject(myTreatment);
                result = (db.SaveChanges() != 0);

            }
            // IF EXISTING TREATMENT, FIND EXISTING TREATMENT IN DB, AND UPDATE IT
            else
            {
                List<string> treatmentIncludes = new List<string>();
                treatmentIncludes.Add("Segments");

                Treatment myTmt = (from x in db.Treatments
                                   where x.Treatment_ID == myTreatment.Treatment_ID
                                   select x).WithIncludes(treatmentIncludes).FirstOrDefault();

                if (myTmt != null)
                {

                    myTmt.Comment = myTreatment.Comment;
                    myTmt.Cost = myTreatment.Cost;
                    myTmt.CostItemDrain = myTreatment.CostItemDrain;
                    myTmt.CostItemE2E = myTreatment.CostItemE2E;
                    myTmt.CostItemEnhan = myTreatment.CostItemEnhan;
                    myTmt.CostItemEnv = myTreatment.CostItemEnv;
                    myTmt.CostItemGuard = myTreatment.CostItemGuard;
                    myTmt.CostItemOther = myTreatment.CostItemOther;
                    myTmt.CostItemPed = myTreatment.CostItemPed;
                    myTmt.CostItemSub = myTreatment.CostItemSub;
                    myTmt.CostItemTraffic = myTreatment.CostItemTraffic;
                    myTmt.CostItemUtl = myTreatment.CostItemUtl;
                    myTmt.Create_DateTime = myTreatment.Create_DateTime;
                    myTmt.Create_Entity = myTreatment.Create_Entity;
                    myTmt.Create_User = myTreatment.Create_User;
                    myTmt.Description = myTreatment.Description;
                    myTmt.Improvement_Type = myTreatment.Improvement_Type;
                    myTmt.Jurisdiction = myTreatment.Jurisdiction;
                    myTmt.Last_Update_DateTime = myTreatment.Last_Update_DateTime;
                    myTmt.Last_Update_Entity = myTreatment.Last_Update_Entity;
                    myTmt.Last_Update_User = myTreatment.Last_Update_User;
                    myTmt.Life_Expectancy = myTreatment.Life_Expectancy;
                    myTmt.MDOTJobID = myTreatment.MDOTJobID;
                    myTmt.Planned = myTreatment.Planned;
                    myTmt.Project_Classification = myTreatment.Project_Classification;
                    myTmt.ProjectID = myTreatment.ProjectID;
                    myTmt.Quantity = myTreatment.Quantity;
                    myTmt.SurfaceTypeAfter = myTreatment.SurfaceTypeAfter;
                    myTmt.tmp_treat = myTreatment.tmp_treat;
                    myTmt.Treatment_Date = myTreatment.Treatment_Date;
                    myTmt.Unit_of_Measure = myTreatment.Unit_of_Measure;



                    // DELETE MISSING SEGMENTS THAT ARE NO LONGER PART OF THE TREATMENT
                    List<int> segmentIDsToKeep = myTreatment.Segments.Select(x => x.SegmentID).ToList();
                    myTmt.Segments.Where(x => !segmentIDsToKeep.Contains(x.SegmentID)).ToList().ForEach(x => db.Segments.DeleteObject(x));


                    // ITERATE OVER EACH SEGMENT AND INSERT OR UPDATE IT
                    foreach (Segment s in myTreatment.Segments)
                    {

                        if (!string.IsNullOrWhiteSpace(s.PR) && !string.IsNullOrWhiteSpace(s.BMP.ToString()) && !string.IsNullOrWhiteSpace(s.EMP.ToString()))
                        {
                            Segment mySegment = new Segment();

                            // IF EXISTING SEGMENT, FIND EXISTING SEGMENT IN DB, AND UPDATE IT
                            if (s.SegmentID != 0)
                            {
                                mySegment = (from x in myTmt.Segments
                                             where x.SegmentID == s.SegmentID
                                             select x).FirstOrDefault();
                            }

                            mySegment.ActualLength = s.ActualLength;
                            mySegment.BMP = s.BMP;
                            mySegment.Create_DateTime = s.Create_DateTime;
                            mySegment.Create_Entity = s.Create_Entity;
                            mySegment.Create_User = s.Create_User;
                            mySegment.EMP = s.EMP;
                            mySegment.HasRequiredHPMS = s.HasRequiredHPMS;
                            mySegment.Lanes = s.Lanes;
                            mySegment.Last_Update_DateTime = s.Last_Update_DateTime;
                            mySegment.Last_Update_Entity = s.Last_Update_Entity;
                            mySegment.Last_Update_User = s.Last_Update_User;
                            mySegment.PASER_Rating = s.PASER_Rating;
                            mySegment.PR = s.PR;
                            mySegment.RoadName = s.RoadName;
                            mySegment.SurfaceType = s.SurfaceType;
                            mySegment.Treatment_ID = s.Treatment_ID;
                            mySegment.Version = s.Version;

                            // If the BMP is greater than the EMP, swap them.
                            if (mySegment.BMP > mySegment.EMP)
                            {
                                decimal tempBMP = mySegment.BMP;
                                decimal tempEMP = mySegment.EMP;

                                mySegment.BMP = tempEMP;
                                mySegment.EMP = tempBMP;
                            }


                            // IF NEW SEGMENT, ADD IT
                            if (s.SegmentID == 0)
                            {
                                myTmt.Segments.Add(mySegment);
                            }



                        }

                    }

                    result = (db.SaveChanges(SaveOptions.AcceptAllChangesAfterSave) != 0);
                }

            }



        }

        return result;
    }

Answer 1

将行插入 Oracle 表时，我遇到了同样的错误，解决了将 edmx 文件编辑为 xml（右键单击，打开方式...，XML 编辑器）并添加 StoreGeneratedPattern="Identity"到表定义的问题。

前

<Property Name="ID" Type="number" Nullable="false" Precision="38" Scale="0" />

后

<Property Name="ID" Type="number" Nullable="false" Precision="38" Scale="0" StoreGeneratedPattern="Identity" />

Answer 2

问题是您Segment在上下文中两次分配相同的键，这会弄乱 ObjectStateManager。

myTreatment有一个实体集合Segment，所有实体都被跟踪。现在，当您循环遍历它们时，您创建了另一个Segment，它最终可能与Segment集合中的现有密钥具有相同的密钥：

foreach (Segment s in myTreatment.Segments){
    ....
    Segment mySegment = new Segment(); //NEW OBJECT

    if (s.SegmentID != 0)
    {
        //IN HERE YOU ASSIGN THE SAME KEY TO THE NEW OBJECT
        //s.SegmentID == mySegment.SegmentID **CONFLICT**
        mySegment = (from x in myTmt.Segments
                    where x.SegmentID == s.SegmentID
                    select x).FirstOrDefault();
    }