Linq2Sql 克隆对象 C#

Question

tblAgreement AgreementOld = (from g in TDC.tblAgreements
                             where g.AccountID == ids.accountID && g.AgreementID == AgreementID
                            select g).SingleOrDefault();

Guid AgreementIDNew = Guid.NewGuid();
var AgreementNew = AgreementOld;
AgreementNew.AgreementID = AgreementIDNew;
AgreementNew.StatusChangeDate = DateTime.Now;
AgreementNew.CreationDate = DateTime.Now;
AgreementNew.AccountID = ids.accountID;
AgreementNew.CreatedByID = ids.userID;
TDC.tblAgreements.InsertOnSubmit(AgreementNew);

我正在尝试创建一个与旧对象具有相同值的新对象，但我收到此错误消息；

Cannot add an entity that already exists.

注意：我不想删除旧对象。请帮助我，我有 google 但找不到任何帮助或解决方案。

Answer 1

您需要创建一个新对象，目前您的新对象也引用了旧对象：

var AgreementNew = new Agreement();  // create a new instance
AgreementNew.SomeProperty = AgreementOld.SomeProperty; // assign property from old to new
AgreementNew.AgreementID = AgreementIDNew; // new proerties here
AgreementNew.StatusChangeDate = DateTime.Now;
AgreementNew.CreationDate = DateTime.Now;
AgreementNew.AccountID = ids.accountID;
AgreementNew.CreatedByID = ids.userID;
TDC.tblAgreements.InsertOnSubmit(AgreementNew);

Answer 2

如果 AgreementOld 是 DataTable 则直接执行

var AgreementNew = AgreementOld.Copy();