Question

问题：

我无法创建和实体并将其保存到数据库。实体表示拥有personal_data实体（组成）的客户，最后一个在组成中也具有和地址，并且地址具有与现有实体的关系。

型号和代码：

型号：

[Table("customers")]
public class Customer
{
    public int ID { get; set; }

    public string comments { get; set; }

    public virtual PersonalData personal_data { get; set; }

    public virtual User User { get; set; }
}

[Table("personal_datas")]
public class PersonalData
{
    [Key]
    [Column("id")]
    public int ID { get; set; }

    public string name { get; set; }

    ...

    public virtual Address address { get; set; }
}

[Table("addresses")]
public class Address
{
    public int ID { get; set; }

    public string address1 { get; set; }

    ...

    public int region_id { get; set; }

    [ForeignKey("region_id")]
    public virtual Region region { get; set; }
}

[Table("regions")]
public class Region
{
    public int ID { get; set; }

    [LocalizedDisplayName("Nombre")]
    public string name { get; set; }        

    public virtual Country country { get; set; }
}

代码：

        Customer customer = new Customer();
        customer.comments = "XXX";
        customer.personal_data = new PersonalData();
        customer.personal_data.last_name_1 = "";
        customer.personal_data.last_name_2 = "";
        customer.personal_data.address = new Address();
        customer.personal_data.address.address1 = "";
        customer.personal_data.address.cp = "";
        customer.personal_data.address.city = "";
        customer.personal_data.address.region_id = 0;

        db.Entry(customer).State = EntityState.Added;
        db.Entry(customer.personal_data).State = EntityState.Added;
        db.Entry(customer.personal_data.address).State = EntityState.Added;

        db.SaveChanges();

错误：

'保存不公开其关系的外键属性的实体时发生错误。 EntityEntries属性将返回null，因为无法将单个实体标识为异常的来源。通过在实体类型中公开外键属性，可以简化保存时的异常处理。有关详细信息，请参见InnerException。'

重点是，这可以在控制器上执行编辑操作：

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Edit([Bind(Include = "ID,comments,personal_data")] Customer customer)
    {
        if (ModelState.IsValid)
        {
            db.Entry(customer).State = EntityState.Modified;
            db.Entry(customer.personal_data).State = EntityState.Modified;
            db.Entry(customer.personal_data.address).State = EntityState.Modified;
            db.SaveChanges();
            return RedirectToAction("Edit", new { id = customer.ID });
        }
        return View(customer);
    }

任何想法？

修改

我已将“地址”添加到“区域”：

public ICollection<Address> Addresses { get; set; }

然后在“ OnModelCreating”中输入：

modelBuilder.Entity<Address>()
        .HasRequired<Region>(s => s.region)
        .WithMany(g => g.Addresses)
        .HasForeignKey<int>(s => s.region_id);

该错误仍然存在。

Answer 1

您需要向数据库上下文提供外键，以便EF可以在创建时满足它。我不知道您的数据库布局，但是在上下文中，一对多关系看起来像下面的样子

this link should be helpful with setup as well

modelBuilder.Entity<MyModel>(entity =>
        {
            ...removed other configuration for brevity

            entity.HasOne(d => d.MyOtherModel)
                .WithMany(p => p.MyModel)
                .HasForeignKey(d => d.MyModelKey)
                .OnDelete(DeleteBehavior.ClientSetNull)
                .HasConstraintName("FK_My_Foreign_Key_Name");
        });

MVC + EF：通过下拉选择创建具有相关属性的实体时出现问题

1 个答案: