Question

初学者与实体框架和mvc在这里。我有2个桌子模型：

用户配置

[Table("UserProfile")]
public class UserProfile
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int UserId { get; set; }
    public string UserName { get; set; }
    public string Email { get; set; }
}

和

ChatLogs

[Table("ChatLogs")]
public class ChatLogs
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int ChatLogId { get; set; }
    [Column("Message")]
    public string Message { get; set; }
    [Column("UserId")]
    public int UserId { get; set; }

    public override string ToString()
    {
        return "Person: " + Message + " " + UserId;
    }

}

表ChatLogs中的UserId是UserPorfile UserId主键的外键。

我正在尝试在Asp.NET MVC 4中加入这两个表

经过测试的SQL查询：

select * from UserProfile as a join ChatLogs as b on a.UserId = b.UserId

经过测试的Linq查询：

from b in db.ChatLogs
select new {
  ChatLogId = b.ChatLogId,
  Message = b.Message,
  UserId = b.UserId,
  Column1 = (int?)b.UserProfile.UserId,
  UserName = b.UserProfile.UserName,
  Email = b.UserProfile.Email
}

我正在使用名为“Linqer”的软件进行学习。它将SQL转换为Linq。

ActionResult代码：

private ChatLogContext db = new ChatLogContext();
public ActionResult Index()
{
    var list = from b in db.ChatLogs
               select new
               {
                   ChatLogId = b.ChatLogId,
                   Message = b.Message,
                   UserId = b.UserId,
                   Column1 = (int?)b.UserProfile.UserId,
                   UserName = b.UserProfile.UserName,
                   Email = b.UserProfile.Email
                   };


    var vm = new ChatLogsViewModel { LogListString = string.Join("\n", list) };
    return View(vm);

}

ChatLogViewModel只有一个字符串变量，用于在视图中打印列表。

但是我收到了一个错误：

'Chat.Models.ChatLogs' does not contain a definition for 'UserProfile' and no extension method 'UserProfile' accepting a first argument of type 'Chat.Models.ChatLogs' could be found (are you missing a using directive or an assembly reference?)

所以我必须以某种方式连接这两个实体，以便他们彼此了解？

Answer 1

试试这个：

[Table("UserProfile")]
public class UserProfile
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int UserId { get; set; }
    public string UserName { get; set; }
    public string Email { get; set; }
    **public virtual ICollection<ChatLogs> ChatLogs { get; set; }**
}

[Table("ChatLogs")]
public class ChatLogs
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int ChatLogId { get; set; }
    [Column("Message")]
    public string Message { get; set; }
    [Column("UserId")]
    public int UserId { get; set; }

    **public virtual UserProfile UserProfile { get;set; }**

    public override string ToString()
    {
        return "Person: " + Message + " " + UserId;
    }

}

Answer 2

最简单的连接方式是将Chatlog作为List提供给用户：

[Table("UserProfile")]
public class UserProfile
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int UserId { get; set; }
    public string UserName { get; set; }
    public string Email { get; set; }

    public List<ChatLog> ChatLogs{ get; set;}
}

现在您可以执行以下操作：

var users = Users.Include("ChatLogs");

每个用户现在都可以正确填写其ChatLog列表。

实体框架连接2个表

2 个答案: