linq 和自动增量

Question

错误：

“System.Data.SqlClient.SqlException”类型的未处理异常 发生在 System.Data.Linq.dll 附加信息：违反 PRIMARY KEY 约束“PK_users”。无法在对象“dbo.users”中插入重复键。这 重复键值为 (0)。 声明已终止。

代码：

private void register_Click(object sender, RoutedEventArgs e)
{
    var _user = new user();
    if (username.Text.Length == 0)
    {
        username.Text = "Geef gebruikersnaam in";
    }
    else if (password.Text.Length == 0)
    {
        password.Text = "Voer wachtwoord in";
    }
    else if (password.Text != passcon.Text)
    {
        password.Text = "Wachtwoorden niet gelijk";
    }
    else
    {
        using (MD5 md5Hash = MD5.Create())
        {
            _user.password = md5Hash.ComputeHash(Encoding.UTF8.GetBytes(password.Text));
        }
        _user.username = username.Text;

        bool contactExists = _dataDC.users.Any(x => x.username.Equals(_user.username));
        if (contactExists)
        {
            MessageBox.Show("Gebruiker bestaat al");
        }
        else
        {
            _dataDC.users.InsertOnSubmit(_user);
            _dataDC.SubmitChanges();

            MessageBox.Show("Registratie succesvol");
            MainWindow _main = new MainWindow();
            _main.Show();
            this.Close();
        }
    }
}

我正在使用 SQL Server 管理器。我表中的主键是“ID”。启用自动增量。我没有在任何地方设置 id，所以它在技术上是 null，但我得到了这个错误。有什么解决办法吗？

编辑：模型类：

public user user
        {
            get
            {
                return this._user.Entity;
            }
            set
            {
                user previousValue = this._user.Entity;
                if (((previousValue != value) 
                            || (this._user.HasLoadedOrAssignedValue == false)))
                {
                    this.SendPropertyChanging();
                    if ((previousValue != null))
                    {
                        this._user.Entity = null;
                        previousValue.recipients.Remove(this);
                    }
                    this._user.Entity = value;
                    if ((value != null))
                    {
                        value.recipients.Add(this);
                        this._recipient1 = value.username;
                    }
                    else
                    {
                        this._recipient1 = default(string);
                    }
                    this.SendPropertyChanged("user");
                }
            }
        }

属性改变了：

public partial class user : INotifyPropertyChanging, INotifyPropertyChanged
    {

        private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);

        private int _userid;

        private string _username;

        private System.Data.Linq.Binary _password;

        private EntitySet<email> _emails;

        private EntitySet<recipient> _recipients;

    #region Extensibility Method Definitions
    partial void OnLoaded();
    partial void OnValidate(System.Data.Linq.ChangeAction action);
    partial void OnCreated();
    partial void OnuseridChanging(int value);
    partial void OnuseridChanged();
    partial void OnusernameChanging(string value);
    partial void OnusernameChanged();
    partial void OnpasswordChanging(System.Data.Linq.Binary value);
    partial void OnpasswordChanged();
    #endregion

        public user()
        {
            this._emails = new EntitySet<email>(new Action<email>(this.attach_emails), new Action<email>(this.detach_emails));
            this._recipients = new EntitySet<recipient>(new Action<recipient>(this.attach_recipients), new Action<recipient>(this.detach_recipients));
            OnCreated();
        }

        [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_userid", DbType="Int NOT NULL", IsPrimaryKey=true, IsDbGenerated=true)]
        public int userid
        {
            get
            {
                return this._userid;
            }
            set
            {
                if ((this._userid != value))
                {
                    this.OnuseridChanging(value);
                    this.SendPropertyChanging();
                    this._userid = value;
                    this.SendPropertyChanged("userid");
                    this.OnuseridChanged();
                }
            }
        }

        [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_username", DbType="VarChar(50) NOT NULL", CanBeNull=false)]
        public string username
        {
            get
            {
                return this._username;
            }
            set
            {
                if ((this._username != value))
                {
                    this.OnusernameChanging(value);
                    this.SendPropertyChanging();
                    this._username = value;
                    this.SendPropertyChanged("username");
                    this.OnusernameChanged();
                }
            }
        }

        [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_password", DbType="VarBinary(MAX) NOT NULL", CanBeNull=false, UpdateCheck=UpdateCheck.Never)]
        public System.Data.Linq.Binary password
        {
            get
            {
                return this._password;
            }
            set
            {
                if ((this._password != value))
                {
                    this.OnpasswordChanging(value);
                    this.SendPropertyChanging();
                    this._password = value;
                    this.SendPropertyChanged("password");
                    this.OnpasswordChanged();
                }
            }
        }

Answer 1

您需要将您的 id 属性标记为自动生成。根据您使用的技术，可以在设计器中对其进行修改，向属性添加[Key] 属性，或者使用流利的配置将其配置为键。

在 LINQ to SQL 设计器中，将 AutoGenerated 属性设置为 true 并将 Auto-Sync 设置为 OnInsert - auto generate in LINQ to SQL