1
我有一個定義,就像下面,基本上,我想在EmailAccount類來創建此:如何使用CodeFirst(的EntityFramework,微軟),使可空列複雜
公共EmailUser? EmailUserAccountInfo {get; set;}
編譯器給我一個關於非空類型的錯誤。我的目標是我想讓EmailUser可選。我有點困惑,因爲我可以直接設置EmailUserAccountInfo = null。
var r = new EmailAccount()
{
EmailUserAccountInfo = null,
Id = 1001
};
public class EmailAccount
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public EmailUser EmailUserAccountInfo { get; set; }
}
public class EmailUser
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public EmailAccount EmailAcount { get; set; }
public string EmailAddress { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string ZipCode { get; set; }
public string City { get; set; }
public string State { get; set; }
public int Temperature { get; set; }
public string WeatherString { get; set; }
public ImageDetail ImageOfUser { get; set; }
}
謝謝Tsuushin,你能解釋一下virtual關鍵字在數據庫中的含義嗎?另外,我對添加外鍵列是否明確有所影響有一些疑問。 –
顯式添加外鍵允許您將其標記爲無效,從而指示EF關係爲零對一。 –
至於虛擬關鍵字,請參閱[對此問題的答案](http://stackoverflow.com/questions/5597760/what-effects-can-the-virtual-keyword-have-in-entity-framework-4- 1-POCO碼-FI) –