InsertOnSubmit-NullReferenceException

Question

我有2個模型。

帳戶實體

[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; }
    }

詳細實體

[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; }
}

主要

 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();
 }

關系為AccountEntity <- DetailsEntity (1-n)

當我嘗試插入記錄時，拋出異常（ NullReferenceException ）

原因：由EntitySet null

請幫我把它插入。

---

我在發現問題

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

如果沒有引用，則必須是新實例

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

Answer 1

嘗試使用以下內容更新詳細信息表

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

因為您需要在將數據插入時生成主鍵。

希望這會有所幫助。