Entity Framework 3.1 一对多插入数据

Question

我有 Offer 和 OfferLocation。一个报价可以有多个报价位置。在保存报价时，我还想将报价位置保存到报价位置表中，但我收到一条错误消息：

“Microsoft.EntityFrameworkCore.DbUpdateException：更新条目时出错。有关详细信息，请参阅内部异常。\r\n ---> Microsoft.Data.SqlClient.SqlException (0x80131904)：无法为标识插入显式值当 IDENTITY_INSERT 设置为 OFF 时，表“OfferLocation”中的列

请在下面找到代码：

public class Offer
{
    public int Id { get; set; }
    public virtual ICollection<OfferLocation> OfferLocations { get; set; }
    ...

}

public class OfferLocation
{
    public int Id { get; set; }
    public int OfferId { get; set; }

    [ForeignKey("OfferId")]
    public virtual Offer Offer { get; set; }
    ...
}

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
     modelBuilder.Entity<OfferLocation>().HasKey(od => new { od.Id, od.OfferId});
     modelBuilder.Entity<OfferLocation>().HasOne(od => od.Offer).WithMany(od => od.OfferLocations).HasForeignKey(od => od.OfferId);
}


public class OfferRepository : BaseRepository<OfferModel>, IOfferRepository
{
        public OfferRepository(Func<MMADbContext> contexFactory) : base(contexFactory) { }

        public async Task<OfferModel> CreateAsync(OfferModel model)
        {
            var context = ContextFactory();
            var offer = new Offer();
            var offerLocations = new List<OfferLocation>();
           

            context.Add(offer);

            foreach (var location in model.Locations)
            {
                OfferLocation offerLocation = new OfferLocation();
                offerLocation.Id = location.Id;
                offerLocation.Country = location.Country;
                offerLocation.Latitude = location.Latitude;
                offerLocation.Longtitude = location.Longtitude;
                offerLocation.Offer = offer;
                offerLocation.Vicinity = location.Vicinity;

                offerLocations.Add(offerLocation);

            }

            offer.OfferLocations = offerLocations;
            await context.SaveChangesAsync();

            return...
        }
    }
}

我知道问题与插入键和/或外键有关，但我知道如何解决它。任何帮助表示赞赏。

Answer 1

在这一行

modelBuilder.Entity<OfferLocation>().HasKey(od => new { od.Id, od.OfferId});

您正在尝试使用复合主键，但您只需要 (od => od.Id)

id 是你唯一的主键

还有 您不需要在OnModelCreating 中使用注解[ForeignKey("OfferId")] 甚至是流畅的api 配置，因为您已经使用了“有效约定”

您可以访问此link，了解有关与约定建立关系的更多信息

Answer 2

Remove the identiy的

offerLocation.Id

数据库列。您正在尝试将 Identity 设置为主键，但不允许这样做。