ASP.Net核心不斷抱怨“資料庫操作預計會影響1行，但實際上影響了0行”

我遇到了上述錯誤，不知道該怎么辦。

您可以假設表已正確設定。這是問題代碼：

    var setting = _context.Settings.FirstOrDefault();
    ICollection<PD_Datafile> PD_Datafiles = new Collection<PD_Datafile>();

    
    for (int i = 0; i < numfiles; i  )
    {
        DAT_FILE PD_Datafile = ParseFileName(files[i].Name, filepath);
        string databodystr = Encoding.Default.GetString(PD_Datafile.SensorData.DataBody);
        PD_Datafiles.Add(new PD_Datafile() { DataId = i, FullName = files[i].Name, DataBody = databodystr });
    }

    setting.PD_Datafiles = PD_Datafiles;

    ICollection<Alarm> alarms = new Collection<Alarm>();
    alarms.Add(new Alarm() { AlarmId = 0, DateOccurred = 20210120, EquipmentType = "GISPD", FaultType = "PD Happening", Sensor = null, Details = "None" });
    alarms.Add(new Alarm() { AlarmId = 1, DateOccurred = 20210121, EquipmentType = "CBCM", FaultType = "Warning", Sensor = null, Details = "None" });
    alarms.Add(new Alarm() { AlarmId = 2, DateOccurred = 20210122, EquipmentType = "DGA", FaultType = "Danger", Sensor = null, Details = "None" });
    alarms.Add(new Alarm() { AlarmId = 3, DateOccurred = 20210123, EquipmentType = "OLTC", FaultType = "Danger", Sensor = null, Details = "None" });
   
    setting.Alarms = alarms;
    _context.Settings.Update(setting);
    
    _context.SaveChanges();

當 '_context' 保存更改時，它一直說“'資料庫操作預計會影響 1 行，但實際上影響了 0 行。自從加載物體以來，資料可能已被修改或洗掉。”

經過一番谷歌搜索后，我也在每個表的主鍵上方添加了這個符號。

[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]

我想我以某種錯誤的方式添加了串列。

以下是我正在使用的表格：

namespace OA2.Model
{
    public class Alarm
    {
        [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int AlarmId { get; set; }
        public string FaultType { get; set; }
        public int DateOccurred { get; set; }
        public Sensor Sensor { get; set; }
        public string EquipmentType { get; set; }
        public string Details { get; set; }
        [ForeignKey("SettingId")]
        public virtual Setting Setting { get; set; }
    }
}

namespace OA2.Model
{
    public partial class Setting
    {
        
        public Setting()
        {
            PD_Datafiles = new HashSet<PD_Datafile>();
            SCBR_Datafiles = new HashSet<SCBR_Datafile>();
            Alarms = new HashSet<Alarm>();
        }

        [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int SettingId { get; set; }
        public int EventAmpTh1 { get; set; }
        public int EventPpsTh1 { get; set; }
        public int EventAmpTh2 { get; set; }
        public int EventPpsTh2 { get; set; }
        public int PulselvlTh { get; set; }
        public long TimePassed { get; set; }
        public string FilePath { get; set; }
        //public virtual PD_Datafile Data { get; set; }
        public virtual ICollection<PD_Datafile> PD_Datafiles { get; set; }
        public virtual ICollection<SCBR_Datafile> SCBR_Datafiles { get; set; }
        public virtual ICollection<Alarm> Alarms { get; set; }

    }
}

我在這里先向您的幫助表示感謝！

uj5u.com熱心網友回復：

看：[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int AlarmId { get; 放; }

這意味著資料庫將生成AlarmId，因此您在創建新物件Alarm物件時無需分配AlarmId。

讓我們洗掉 AlarmId = 0、AlarmId = 1 等...

uj5u.com熱心網友回復：

我認為警報桌上有問題。警報的 ID 是身份，因此您不需要添加警報 ID 第二件事是您同時修改兩個表可能會出現例外。

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