InsertOnSubmit - NullReferenceException

Question

我有两个模特。

AccountEntity

[Table(Name = "Account")]
    public class AccountEntity
    {
        [Column(IsPrimaryKey = true, IsDbGenerated = true, AutoSync = AutoSync.OnInsert)]
        public int id { get; set; }
        [Column(CanBeNull = false, Name = "email")]
        public string email { get; set; }
        [Column(CanBeNull = false, Name = "pwd")]
        public string pwd { get; set; }
        [Column(CanBeNull = false, Name = "row_guid")]
        public Guid guid { get; set; }

        private EntitySet<DetailsEntity> details_id { get; set; }
        [Association(Storage = "details_id", OtherKey = "id", ThisKey = "id")]
        public ICollection<DetailsEntity> detailsCollection { get; set; }
    }

DetailsEntity

[Table(Name = "Details")]

    public class DetailsEntity
    {
    public DetailsEntity(AccountEntity a) {
        this.Account = a;
    }

    [Column(IsPrimaryKey = true, IsDbGenerated = true, DbType = "int")]
    public int id { get; set; }

    private EntityRef<AccountEntity> _account = new EntityRef<AccountEntity>();
    [Association(IsForeignKey = true, Storage = "_account", ThisKey = "id")]
    public AccountEntity Account { get; set; }
}

Main

 using (Database db = new Database())
 {
     AccountEntity a = new AccountEntity();
     a.email = "hahaha";
     a.pwd = "13212312";
     a.guid = Guid.NewGuid();
     db.Account.InsertOnSubmit(a);
     db.SubmitChanges();
 }

有关系的AccountEntity <- DetailsEntity (1-n)

当我试图插入记录时，会引发异常(NullReferenceException)

原因: by EntitySet null

请帮我把它插入。

我发现问题出在

private EntitySet<DetailsEntity> details_id { get; set; } // this is properties 

如果没有引用，这必须是新实例。

private EntitySet<DetailsEntity> details_id = new EntitySet<DetailsEntity>();

Answer 1

尝试用以下内容更新Details表

[Column(IsPrimaryKey = true, IsDbGenerated = true, AutoSync = AutoSync.OnInsert)]

因为您需要生成数据进入其中的主键。

希望这能帮上忙。