Question

我是实体框架概念的新手。我为“用户列表”和角色创建模型，这些模型将确定那里受到尊重的访问。用户可以有多个角色，而角色可以有多个用户

 public class TblUser
{
    [Key]
    [MaxLength(50)]
    public string UserID { get; set; }
    [MaxLength(35)]
    public string UserName { get; set; }
    [MaxLength(150)]
    public string EMailAddress { get; set; }
    [MaxLength(150)]
    public string Password { get; set; }
    public DateTime LastLogIn { get; set; }
    [MaxLength(3)]
    public string ResetPassword { get; set; }
    [MaxLength(150)]
    public string ResetNewPassword { get; set; }
    public DateTime ResetPasswordExpire { get; set; }
    [MaxLength(3)]
    public string Active { get; set; }
    public List<TblRole> Roles { get; set; }
}

public class TblRole
{
    [Key]
    [MaxLength(50)]
    public string RoleID { get; set; }
    [MaxLength(50)]
    public string RoleName { get; set; }
    public List<TblUser> Users { get; set; }
}

这是我的数据库

我现在正在尝试使用以下代码添加新用户，但出现此错误 {“约束失败\ r \ n唯一约束失败：TblRole.RoleID”}

public string addNewUser(string Username, string Email, Model.DB.TblRole roles)
    {
        using (DatabaseContext db = new DatabaseContext())
        {
            ExpenseMonitoringSystem.Controller.Security sec = new Security();
            string randomPassword = sec.Encrypt(RandomString(6, false));

            if((from user in db.TblUser where user.UserName==Username select user).FirstOrDefault()!=null)
                throw new Exception("The username is already used");
            if ((from user in db.TblUser where user.EMailAddress == Email select user).FirstOrDefault() != null)
                throw new Exception("The email is already used");

            var newuser = new ExpenseMonitoringSystem.Model.DB.TblUser
                {
                    UserID = Guid.NewGuid().ToString(),
                    Password = randomPassword,
                    UserName = Username,
                    ResetPassword = "YES",
                    ResetNewPassword = randomPassword,
                    ResetPasswordExpire = DateTime.Now.AddDays(10),
                    EMailAddress = Email,
                    Active = "YES",
                    Roles = new List<Model.DB.TblRole>() { roles }
                };

            db.TblUser.Add(newuser);

            db.SaveChanges();
            return randomPassword;
        }
    }

Answer 1

约束失败\ r \ n唯一约束失败：TblRole.RoleID

可能意味着您正在尝试向数据库中添加TblRole，但是已经有一个具有相同RoleID的现有记录。

查看您的代码，好像您将roles放在某个地方，然后创建了DatabaseContext，db的新实例。问题是，db在您调用roles时认为db.TblUser.Add(newuser)是新记录。要告诉db数据库中已经存在roles，可以在添加db.TblRole.Attach之前在TblRole中的每个roles上调用newUser。

您可以learn more about that concept (entity states) here。

Answer 2

使用Fluent API配置多对多关系

您可以了解有关实体关系here

的更多信息

EF以多对多关系插入记录

2 个答案: