Question

我有两个相关的模型。

public class RolesModels
{
    public RolesModels()
    {
        this.Users = new HashSet<UserModels>();
    }

    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int RoleId { get; set; }

    [Required]
    [DataType(DataType.Text)]
    [StringLength(20, ErrorMessage = "The {0} must be at least 6 characters long.", MinimumLength = 6)]
    [Display(Name = "Caption")]
    public string Caption { get; set; }

    [Display(Name = "Can Create")]
    public bool createRole { get; set; }

    [Display(Name = "Can View")]
    public bool viewRole { get; set; }


    [Display(Name = "Can Modify")]
    public bool modifyRole { get; set; }

    [Display(Name = "Can Delete")]
    public bool deleteRole { get; set; }

    public virtual ICollection<UserModels> Users { get; set; }

}

，第二个是这样的

   public class UserModels
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]

    public int user_id { get; set; }

    [Required]
    [DataType(DataType.Text)]
    [Display(Name = "User Name")]
    [StringLength(20, ErrorMessage = "The {0} must be at least 3 characters long.", MinimumLength = 3)]
    public string user_name { get; set; }

    [Required]
    [DataType(DataType.Password)]
    [Display(Name = "Password")]
    [StringLength(10, ErrorMessage = "The {0} must be at least 4 characters long.", MinimumLength = 4)]
    public string user_pass { get; set; }

    [DataType(DataType.EmailAddress)]
    [Display(Name = "Email")]
    [StringLength(50, ErrorMessage = "The {0} must be at least 6 characters long.", MinimumLength = 6)]
    public string UserEmail { get; set; }

    [Display(Name = "Registeration Date")]
    [DataType(DataType.Date)]
    [DisplayFormat(DataFormatString = "{0:dd-MM-yyyy}", ApplyFormatInEditMode = true)]
    public DateTime RegDate { get; set; }

    [Display(Name = "Enable User")]
    public bool status { get; set; }

    //[Bindable(false)]
    public int RoleId { get; set; }

    [Display(Name = "User Roles")]
    public virtual RolesModels Roles { get; set; }

}

问题是，我希望能够使用以下列检索记录：

   User Name | Email | Registration Date | Enable User | Role Caption

这是我的linq to sql code：

  var model = from c in db.UserModels
               join o in db.RolesModels on c.RoleId equals o.RoleId
               where 1==1
               select c;

Answer 1

您不需要where 1=1部分，因为它始终为真，不会影响结果集。您还拥有角色的导航属性，因此您无需手动加入实体：

from u in db.UserModels
select new { 
  UserName = user_name,
  Email = UserEmail,
  RegistrationDate = RegDate,
  EnableUser = status,
  RoleCaption = u.Roles.Caption
}

如果有可能用户无法分配角色，请考虑进行空检查。

Answer 2

你的意思是这个

var model = from c in db.UserModels
               join o in db.RolesModels on c.RoleId equals o.RoleId
               where 1==1
               select new { c.user_name, c.UserEmail, c.RegDate, o.Caption,  c.status}).ToList();

Answer 3

var model = (from c in db.UserModels.AsEnumerable()
               join o in db.RolesModels.AsEnumerable() on c.RoleId equals o.RoleId
               select new { c.user_name, c.UserEmail, c.RegDate, o.Caption,  c.status}).ToList();

做这样的事情。

Answer 4

我能够使用Consoto大学的示例项目来解决这个问题。这是解决方案：

var m = db.UserModels.Include(u => u.Roles);
return View(m.ToList());

和modelItem =＆gt; item.Roles.Caption使用导航属性从Roles模型中获取角色标题。

感谢所有人的尝试。

Linq以sql返回相关数据

4 个答案: