c# - 如何使用 Entity Framework 更改另一个现有实体的相关实体

Question

我有两个类(class):

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; }
}

我想更新 ShipmentRoutePointDb 的 VehicleNumber 以便检索更新记录:

var shipmentRoutePointDb = _shipmentRoutePointRepository.GetByUuid(updatedRoutePoint.Uuid);

然后我需要检查是否应该在 TransportInfoDb 中创建新记录，或者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，我会像这样更新shipmentRoutePointDb:

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();
}

但是 SaveChanges() 抛出了一个异常:

System.InvalidOperationException: "A referential integrity constraintviolation occurred: The property value(s) of 'TransportInfoDb.Id' onone end of a relationship do not match the property value(s) of'ShipmentRoutePointDb.NextTransportId' on the other end."

我知道我没有在那里列出我使用的一些方法，但它们运行良好，它们的名称是不言自明的。

Answer 1

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();
}

这有帮助。主要原因是该项目禁用了检测更改。