asp.net-mvc – 错误：无法在LINQ to Entities查询中构造实体或

发布时间：2020-12-15 19:00:10 所属栏目：asp.Net 来源：网络整理

导读：我有一个与MVC连接查询的问题,我不知道为什么. The entity or complex type ‘Tusofona_Website.Models.site_noticias’ cannot be constructed in a LINQ to Entities query. 我的控制器： private TusofonaDBs db = new TusofonaDBs(); // // GET: /Destaq

我有一个与MVC连接查询的问题,我不知道为什么.

The entity or complex type ‘Tusofona_Website.Models.site_noticias’ cannot be constructed in a LINQ to Entities query.

我的控制器：

private TusofonaDBs db = new TusofonaDBs();

    //
    // GET: /DestaquesMain/

    public ActionResult Index()
    {
        var query = (from sd in db.site_desquesnoticias
                    join sn in db.site_noticias on sd.IDNoticia equals sn.IDNoticia
                    where sn.Destaque == 1
                    select new site_noticias {
                        CorpoNoticia = sn.CorpoNoticia,TituloNoticia = sn.TituloNoticia
                    }).ToList();

        //return View(db.site_desquesnoticias.ToList());
          return View(query);

    }

我的型号：

public class site_destaquesnoticias
{
    [Key]
    public Int32 IDDestaque { get; set; }
    public Int32 IDNoticia { get; set; }
    public string Foto { get; set; }


}

public class site_noticias
{
    [Key]
    public Int32 IDNoticia { get; set; }
    public string CorpoNoticia { get; set; }
    public string TituloNoticia { get; set; }
    public string Foto { get; set; }
    public Int32 Destaque { get; set; }
}

public class TusofonaDBs : DbContext
{
    public DbSet<site_destaquesnoticias> site_desquesnoticias { get; set; }
    public DbSet<site_noticias> site_noticias { get; set; }
}

有人可以帮帮我吗？

解决方法

您无法投影到映射的实体(请参阅 this答案).

但是,您可以做以下几件事：

1)选择匿名类型而不是实体,如：

var query = (from sd in db.site_desquesnoticias
                    join sn in db.site_noticias on sd.IDNoticia equals sn.IDNoticia
                    where sn.Destaque == 1
                    select new {
                        CorpoNoticia = sn.CorpoNoticia,TituloNoticia = sn.TituloNoticia
                    }).ToList();

2)反转您的查询以直接选择site_noticias.这取决于您要检索的查询和数据.例如,您可以查看以下内容是否有效并为您提供所需的数据：

var query = (from sd in db.site_desquesnoticias
                    join sn in db.site_noticias on sd.IDNoticia equals sn.IDNoticia
                    where sn.Destaque == 1
                    select sn).ToList();

3)使用一些DTO(数据传输对象)将要选择的属性投影到：

public class SiteNoticiasDTO{
     public string CorpoNoticia {get;set;}
     public string TituloNoticia {get;set;}
    }

var query = (from sd in db.site_desquesnoticias
                    join sn in db.site_noticias on sd.IDNoticia equals sn.IDNoticia
                    where sn.Destaque == 1
                    select new SiteNoticiasDTO {
                        CorpoNoticia = sn.CorpoNoticia,TituloNoticia = sn.TituloNoticia
                    }).ToList();

（编辑：李大同）

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