使用 EntityFramework 代码优先时，ID 没有更新答案

【问题标题】：Id's not updating when using EntityFramework code-first使用 EntityFramework 代码优先时，ID 没有更新
【发布时间】：2013-05-06 09:41:29
【问题描述】：

在较早的问题之后，我仍在努力使用 EF Code-First；

我有 3 个（在此示例中，实际上还有更多），其中 1 个表使用多个 Id 来访问其他表。

我有两个问题

1：保存到数据库时未设置运输和交付的 ID（保持为“0”）。 2：使用 DBMigrations 时，会为 RecordId 创建两次索引

.Index(t => t.RecordId),
.Index(t => t.RecordId);

代码示例：

记录类：

public class Record
{
    public Record()
    {
        Shipping = new Shipping();
        Delivery = new Delivery();
    }

    public int RecordId { get; set; }
    public int ShippingId { get; set; }
    public int DeliveryId { get; set; }

    public virtual Shipping Shipping { get; set; }
    public virtual Delivery Delivery { get; set; }
}

运输类别：

public class Shipping
{
    public int ShippingId { get; set; }
    public string ShippingName { get; set; }

    public virtual Record Record { get; set; }
}

交付类：

public class Delivery
{
    public int DeliveryId { get; set; }
    public String DeliveryText { get; set; }

    public virtual Record Record { get; set; }
}

上下文：

public class Context : DbContext
{
    public DbSet<Record> Records { get; set; }
    public DbSet<Shipping> Shippings { get; set; }
    public DbSet<Delivery> Deliveries { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {

        modelBuilder.Entity<Record>()
            .HasRequired(m => m.Shipping)
            .WithRequiredDependent(x => x.Record)
            .WillCascadeOnDelete(false);

        modelBuilder.Entity<Record>()
            .HasRequired(m => m.Delivery)
            .WithRequiredDependent(x => x.Record)
            .WillCascadeOnDelete(false);

        base.OnModelCreating(modelBuilder);
    }

主程序（方法）：

using (Context context = new Context())
      {
            var model = context.Records.Create();
            var shipping = model.Shipping;
            shipping.ShippingName = "TestContext";
            var delivery = model.Delivery;
            delivery.DeliveryText = "customText";
            context.Entry(model).State = EntityState.Added;
            context.SaveChanges();
      }

主程序（第二次尝试）

using (Context context = new Context())
      {               
            var model = context.Records.Create();
            model.Shipping = context.Shippings.Create();
            var shipping = model.Shipping;
            shipping.ShippingName = "TestContext";
            model.Delivery = context.Deliveries.Create();
            var delivery = model.Delivery;
            delivery.DeliveryText = "customText";
            context.Entry(model).State = EntityState.Added;
            context.SaveChanges();
      }

【问题讨论】：

标签： entity-framework-4 ef-code-first entity-framework-migrations

【解决方案1】：

为了避免额外的索引，不要在你的记录类中指定关键字段。要获取默认的身份行为名称，关键字段 Id

public class Record
{
    public Record()
    {
        Shipping = new Shipping();
        Delivery = new Delivery();
    }

    public int Id { get; set; }
    public virtual Shipping Shipping { get; set; }
    public virtual Delivery Delivery { get; set; }
}

【讨论】：