C# 如何使用实体框架将相关实体更改为另一个现有实体

我有两门课：

public partial class ShipmentRoutePointDb
{
    public long Id { get; set; } // Primary key
    public System.Guid Uuid { get; set; }
    public virtual TransportInfoDb NextTransportInfo { get; set; }
}

public partial class TransportInfoDb
{
    public TransportInfoDb()
    {
        this.CertifiedConsignments = new HashSet<CertifiedConsignmentDb>();
        this.TransportInfoGroups = new HashSet<TransportInfoGroupDb>();
    }

    public long Id { get; set; }

    public string VehicleNumber { get; set; }

    public virtual ICollection<CertifiedConsignmentDb> CertifiedConsignments { get; set; }
    public virtual ICollection<TransportInfoGroupDb> TransportInfoGroups { get; set; }
}

然后，我需要检查是否在TransportInfoDb中创建了新记录，或者是否已经存在具有类似参数的记录：

var duplicate = transportInfoRepository.GetByParams(shipmentRoutePointDb.NextTransportInfo.VehicleNumber);

如果我能找到这样的记录，我会更新shipmentRoutePointDb，如下所示：

shipmentRoutePointDb.NextTransportInfo = duplicate;
shipmentRoutePointDb.NextTransportId = duplicate.Id;

_shipmentRoutePointRepository.Update2(shipmentRoutePointDb);

public void Update2(ShipmentRoutePointDb entity)
{
    var entr = _context.Entry<ShipmentRoutePointDb>(entity);

    entr.State = EntityState.Modified;

    SaveChanges();
}

shipmentRoutePointDb.NextTransportInfo=重复；
shipmentRoutePointDb.NextTransportId=replicate.Id；
_shipmentRoutePointRepository.Update2（shipmentRoutePointDb）；
公共无效更新2（ShipmentRoutePointDb实体）
{
var entr=_context.Entry（实体）；
entr.State=EntityState.Modified；
保存更改（）；
}

但是SaveChanges（）引发了一个异常：

System.InvalidOperationException:“引用完整性约束 发生冲突：上的“TransportInfoDb.Id”的属性值 关系的一端与的属性值不匹配 另一端为“ShipmentRoutePointDb.NextTransportId”

---

我知道我还没有列出我使用的一些方法，但是它们工作得很好，它们的名称也很简单。

我的朋友，我相信你唯一需要做的就是通过传递id和参数进行如下更新：

public void Update2(var id, type entity)
{
    var result = _context.tableName.SingleOrDefault(b => b.NextTransportId == id);
    if (result != null)
    {
        try
        {
            db.Entry(entity).State = EntityState.Modified;
            db.SaveChanges();
        }
        catch (Exception ex)
        {
            throw;
        }
    }
}

这有帮助。主要原因是在此项目上禁用了检测更改

public void Update2(var id, type entity)
{
    var result = _context.tableName.SingleOrDefault(b => b.NextTransportId == id);
    if (result != null)
    {
        try
        {
            db.Entry(entity).State = EntityState.Modified;
            db.SaveChanges();
        }
        catch (Exception ex)
        {
            throw;
        }
    }
}

public void Update2(long transportId, long shipmentRouteId)
{
    var shipment = _context.ShipmentRoutePointDb.FirstOrDefault(x => x.Id == shipmentRouteId);            
    _context.ShipmentRoutePointDb.Attach(shipment);

    shipment.NextTransportId = transportId;

    _context.ChangeTracker.DetectChanges();

    SaveChanges();
}