Question

我的实体关系是客户＆gt;地址＆gt;联系方式。我正在尝试更新客户表中的数据并从Address＆amp;中删除特定数据。联系人表格并尝试在地址和地址中再次添加数据联系表。

客户ID是地址表中的FK，地址ID是联系人表格中的FK。因此，当我在联系表中插入数据时，我必须传递联系表的AddressID值，但我怎么知道当前的AddressID是什么，因为我删除了一个地址数据并再次插入其ID为联系表要插入的ID。我想在一个SaveChanges()

中做的全部事情

我真的遇到了问题而且不明白如何解决它。这是我的代码。

private void button3_Click(object sender, EventArgs e)
{
    using (var db = new TestDBContext())
    {
    var existingCustomer = db.Customer
    .Include(a => a.Addresses.Select(x => x.Contacts))
    .FirstOrDefault(p => p.CustomerID == 5);

    existingCustomer.FirstName = "Test Customer123";

    existingCustomer.Addresses.Where(a => a.AddressID == 5).ToList().ForEach(r => db.Addresses.Remove(r));
    existingCustomer.Addresses.Where(a => a.AddressID == 5).SelectMany(ad => ad.Contacts).Where(c=> c.ContactID==5).ToList().ForEach(r => db.Contacts.Remove(r));

    Addresses oAdrModel = new Addresses();
    oAdrModel.Address1 = "test xxx";
    oAdrModel.Address2 = "test xxx";
    oAdrModel.SerialNo = 3;
    oAdrModel.IsDefault = true;
    oAdrModel.CustomerID = 5;
    db.Addresses.Add(oAdrModel);
    int xx = oAdrModel.AddressID;

    Contacts ContactModel = new Contacts();
    ContactModel.Phone = "XX-1111111-33";
    ContactModel.Fax = "XX-1-1111111";
    ContactModel.SerialNo = 4;
    ContactModel.IsDefault = true;
    //ContactModel.AddressID = 5;
    db.Contacts.Add(ContactModel);

    db.SaveChanges();
    }
}

ContactModel.AddressID，其值不知道导致问题。

我能想到的一种方法是我可以将数据插入到地址表中，然后我调用SaveChanges()然后我可以获得地址ID ，我可以稍后将其插入到联系表中。我正在寻找最好的建议和指导方针来处理这个问题。感谢

完整工作代码

using (var db = new TestDBContext())
{
    //db.Database.Log = s => MyLogger.Log("EFApp", s);

    var existingCustomer = db.Customer
    .Include(a => a.Addresses.Select(x => x.Contacts))
    .FirstOrDefault(p => p.CustomerID == 5);

    existingCustomer.FirstName = "Test Customer123";

    existingCustomer.Addresses.Where(a => a.AddressID == 5).ToList().ForEach(r => db.Addresses.Remove(r));
    existingCustomer.Addresses.Where(a => a.AddressID == 5).SelectMany(ad => ad.Contacts).Where(c=> c.ContactID==5).ToList().ForEach(r => db.Contacts.Remove(r));

    Addresses oAdrModel = new Addresses();
    oAdrModel.Address1 = "test xxx";
    oAdrModel.Address2 = "test xxx";
    oAdrModel.SerialNo = 3;
    oAdrModel.IsDefault = true;
    oAdrModel.CustomerID = 5;
    db.Addresses.Add(oAdrModel);
    db.SaveChanges();
    int CurAddressID = oAdrModel.AddressID;

    Contacts ContactModel = new Contacts();
    ContactModel.Phone = "XX-1111111-33";
    ContactModel.Fax = "XX-1-1111111";
    ContactModel.SerialNo = 4;
    ContactModel.IsDefault = true;
    ContactModel.AddressID = CurAddressID;
    db.Contacts.Add(ContactModel);

    db.SaveChanges();
}

当前代码

查看我的完整代码，我收到错误对象引用未设置

        using (var db = new TestDBContext())
        {
            //db.Database.Log = s => MyLogger.Log("EFApp", s);

            var existingCustomer = db.Customer
            .Include(a => a.Addresses.Select(x => x.Contacts))
            .FirstOrDefault(p => p.CustomerID == 5);

            existingCustomer.FirstName = "New Customer";

            existingCustomer.Addresses.Where(a => a.AddressID == 5).ToList().ForEach(r => db.Addresses.Remove(r));
            existingCustomer.Addresses.Where(a => a.AddressID == 5).SelectMany(ad => ad.Contacts).Where(c=> c.ContactID==5).ToList().ForEach(r => db.Contacts.Remove(r));

            Addresses oAdrModel = new Addresses();
            oAdrModel.Address1 = "New test xxx";
            oAdrModel.Address2 = "New test xxx";
            oAdrModel.SerialNo = 3;
            oAdrModel.IsDefault = true;
            //oAdrModel.CustomerID = 5;
            existingCustomer.Addresses.Add(oAdrModel);
            //db.Addresses.Add(oAdrModel);
            //db.SaveChanges();
            //int CurAddressID = oAdrModel.AddressID;

            Contacts ContactModel = new Contacts();
            ContactModel.Phone = "New XX-1111111-33";
            ContactModel.Fax = "New XX-1-1111111";
            ContactModel.SerialNo = 4;
            ContactModel.IsDefault = true;
            oAdrModel.Contacts.Add(ContactModel);

            //ContactModel.AddressID = CurAddressID;
            //db.Contacts.Add(ContactModel);

            db.SaveChanges();
        }

EF的POCO课程

public class CustomerBase
{
    public int CustomerID { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }

    [NotMapped]
    public string Address1 { get; set; }

    [NotMapped]
    public string Address2 { get; set; }

    [NotMapped]
    public string Phone { get; set; }

    [NotMapped]
    public string Fax { get; set; }

}

public class Customer : CustomerBase
{
    public virtual List<Addresses> Addresses { get; set; }
}

public class Addresses
{
    [Key]
    public int AddressID { get; set; }
    public string Address1 { get; set; }
    public string Address2 { get; set; }
    public bool IsDefault { get; set; }
    public int SerialNo { get; set; }
    public virtual List<Contacts> Contacts { get; set; }

    public int CustomerID { get; set; }
    //[ForeignKey("CustomerID")]
    public virtual Customer Customer { get; set; }
}

public class Contacts
{
    [Key]
    public int ContactID { get; set; }

    public string Phone { get; set; }
    public string Fax { get; set; }
    public bool IsDefault { get; set; }
    public int SerialNo { get; set; }
    public int AddressID { get; set; }

    //[ForeignKey("AddressID")]
    public virtual Addresses Customer { get; set; } 

}

此行oAdrModel.Contacts.Add(ContactModel);投掷错误未将对象引用设置为对象实例

我的代码有什么问题？请帮我解决。

Answer 1

不是设置父Id属性并将新实体直接添加到相应的DbSet，而只需将它们添加到相应的父集合中：

Addresses oAdrModel = new Addresses() { Contacts = new List<Contacts>() };
oAdrModel.Address1 = "test xxx";
oAdrModel.Address2 = "test xxx";
oAdrModel.SerialNo = 3;
oAdrModel.IsDefault = true;

existingCustomer.Addresses.Add(oAdrModel);

Contacts ContactModel = new Contacts();
ContactModel.Phone = "XX-1111111-33";
ContactModel.Fax = "XX-1-1111111";
ContactModel.SerialNo = 4;
ContactModel.IsDefault = true;

oAdrModel.Contacts.Add(ContactModel);

Answer 2

你可以做两步db.SaveChanges（）;

像这样：

Addresses oAdrModel = new Addresses();
oAdrModel.Address1 = "test xxx";
oAdrModel.Address2 = "test xxx";
oAdrModel.SerialNo = 3;
oAdrModel.IsDefault = true;
oAdrModel.CustomerID = 5;
db.Addresses.Add(oAdrModel);
int xx = oAdrModel.AddressID;
db.Addresses.Add(oAdrModel);

db.SaveChanges();

Contacts ContactModel = new Contacts();
ContactModel.Phone = "XX-1111111-33";
ContactModel.Fax = "XX-1-1111111";
ContactModel.SerialNo = 4;
ContactModel.IsDefault = true;
ContactModel.AddressID = oAdrModel.AddressID;
db.Contacts.Add(ContactModel);

db.SaveChanges();

Answer 3

Addresses oAdrModel = new Addresses();
oAdrModel.Address1 = "test xxx";
oAdrModel.Address2 = "test xxx";
oAdrModel.SerialNo = 3;
oAdrModel.IsDefault = true;
oAdrModel.CustomerID = 5;
db.Addresses.Add(oAdrModel);
int xx = oAdrModel.AddressID;

Contacts ContactModel = new Contacts();
ContactModel.Phone = "XX-1111111-33";
ContactModel.Fax = "XX-1-1111111";
ContactModel.SerialNo = 4;
ContactModel.IsDefault = true;
//ContactModel.AddressID = 5;
ContactModel.Address = oAdrModel
db.Contacts.Add(ContactModel);

db.SaveChanges();

Where Address应该是虚拟地址，并且已加入AddressID：

public class ContacModel{
{
    public  int AddressID { get; set; }
    [ForeignKey("AddressID")]
    public virtual Addresses Address { get; set; }
}

实体框架：如何在子表

完整工作代码

当前代码

3 个答案: