c#lambda表达式错误..这本字典需要类型为的模型项
本文关键字:类型 模型 错误 表达式 字典 c#lambda | 更新日期: 2023-09-27 18:16:21
当我更改查询时,我得到了一个错误。你能帮忙吗?
public ActionResult Index(int? id)
{
Models.MyProjectEntities entity = new Models.MyProjectEntities();
// NORMAL QUERY, NO PROBLEM
//var Messages = entity.Message.Where(x => x.Active);
// JOINED QUERY, GENERATES ERROR
var Messages = entity.Message.Join(entity.Categories,
m => m.CategoriID,
k => k.CategoriID,
(m, k) => new { Message = m, Categories = k })
.Where(x => x.Message.Active);
return View(Messages);
}
这里是aspx文件的第一行
<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<IEnumerable<MyProject.Models.Message>>" %>
这是错误
The model item passed into the dictionary is of type 'System.Data.Objects.ObjectQuery`1[<>f__AnonymousType7`2[MyProject.Models.Message,MyProject.Models.Categories]]', but this dictionary requires a model item of type 'System.Collections.Generic.IEnumerable`1[MyProject.Models.Message]'.
您的视图被声明为采用一组Message
s。
您正试图向它传递一组匿名类型。
正如错误明确指出的那样,它不适合。
相反,您应该创建一个类来保存联接中的数据,然后将视图声明为接受该类的集合
(视图无法轻松使用匿名类型的模型(
因为你的加入是你创建的匿名类型,你需要做
var Messages = entity.Message.Join(entity.Categories,
m => m.CategoriID,
k => k.CategoriID,
(m, k) => new { Message = m, Categories = k })
.Where(x => x.Message.Active)
.Select(x => new Message { ... .. .. } );
public ActionResult Index(int? id)
{
Models.MyProjectEntities entity = new Models.MyProjectEntities();
// NORMAL QUERY, NO PROBLEM
//var Messages = entity.Message.Where(x => x.Active);
// JOINED QUERY, GENERATES ERROR
var Messages = entity.Message.Join(entity.Categories,
m => m.CategoriID,
k => k.CategoriID,
(m, k) => new { Message = m, Categories = k })
.Where(x => x.Message.Active)
.Select(x => x.Message);
return View(Messages);
}
或者,如果你也需要类别,你应该改变视图模型类型
编辑:
public ActionResult Index(int? id)
{
Models.MyProjectEntities entity = new Models.MyProjectEntities();
// NORMAL QUERY, NO PROBLEM
//var Messages = entity.Message.Where(x => x.Active);
// JOINED QUERY, GENERATES ERROR
var Messages = entity.Message.Join(entity.Categories,
m => m.CategoriID,
k => k.CategoriID,
(m, k) => new MessageWithCategories { Message = m, Categories = k })
.Where(x => x.Message.Active);
return View(Messages);
}
模型类型应为MessageWithCategories(必须创建此类(