一个linq to sql 问题

Model代码

//唱片表

[Table(Name="Album")]

public class Album

{

//外键引用

private EntityRef<Genre> _Genre;

private EntityRef<Artist> _Artist;

 

//构造方法

public Album()

{

this._Artist = default(EntityRef<Artist>);

this._Genre = default(EntityRef<Genre>);

}

 

[Column(IsPrimaryKey = true, Name = "AlbumId", DbType = "Int NOT NULL IDENTITY")]

public int AlbumId { get; set; }

[Column(Name="GenreId")]

public int GenreId { get; set; }

[Column(Name = "ArtistId")]

public int ArtistId { get; set; }

[Column(Name = "Title")]

public string Title { get; set; }

[Column(Name="Price")]

public float Price { get; set; }

[Column(Name = "AlbumArtUrl")]

public string AlbumArtUrl { get; set; }

 

[Association(Storage = "_Artist", ThisKey = "ArtistId")]

public Artist Artist

{

get { return this._Artist.Entity; }

set { this._Artist.Entity = value; }

}

[Association(Storage="_Genre",ThisKey="GenreId")]

public Genre Genre

{

get { return this._Genre.Entity; }

set { this._Genre.Entity = value; }

}

}

 

//歌曲风格(流派)

[Table(Name="Genre")]

public class Genre

{

private EntitySet<Album> _Albums;

 

public Genre()

{

this._Albums = new EntitySet<Album>();

}

 

[Column(IsPrimaryKey=true,Name="GenreId")]

public int GenreId { get; set; }

[Column(Name="Name")]

public string Name { get; set; }

[Column(Name = "Description")]

public string Description { get; set; }

 

[Association(Storage = "_Albums", ThisKey = "GenreId")]

public EntitySet<Album> Albums

{

get { return this._Albums; }

set { this._Albums.Assign(value); }

}

}

 

//艺术家

[Table(Name="Artist")]

public class Artist

{

private EntitySet<Album> _Albums;

 

public Artist()

{

this._Albums = new EntitySet<Album>();

}

[Column(IsPrimaryKey=true,Name="ArtistId")]

public int ArtistId { get; set; }

 

[Column]

public string Name { get; set; }

 

[Association(Storage = "_Albums", ThisKey = "ArtistId")]

public EntitySet<Album> Albums

{

get { return this._Albums; }

set { this._Albums.Assign(value); }

}

}

 

//音乐商店

public class MusicStoreModels:DataContext

{

public Table<Album> Albums;

public Table<Genre> Genres;

//默认构造方法

public MusicStoreModels(string connection):base(connection){}

}

音乐风格Controller

[HandleError]

public class HomeController : Controller

{

 

public ActionResult Index()

{

//获得连接字符串

string connStr = ConfigurationManager.ConnectionStrings["MusicStoreContext"].ConnectionString;

//

MusicStoreModels db = new MusicStoreModels(connStr);

 

//获取前10个流派

var viewModel =

(from g in db.Genres

select g).Take(10);

 

ViewData["Genres"] = viewModel;

return View();

}

}

音乐风格展示View

<h2>音乐风格</h2>

<ul>

<%foreach (var gener in (IEnumerable<Genre>)ViewData["Genres"])

{

%><li><%=Html.ActionLink(gener.Name,"Borwse","Store",new{gener=gener.GenreId},new{Title=gener.Description}) %></li><%

} %>

</ul>

唱片Controller

public class StoreController : Controller

{

//

// GET: /Store/

// 某类音乐风格下的唱片

public ActionResult Borwse()

{

//获取查询音乐分类

int gener = Int32.Parse(Server.HtmlEncode(Request.QueryString["gener"]));

 

//获得连接字符串

string connStr = ConfigurationManager.ConnectionStrings["MusicStoreContext"].ConnectionString;

 

MusicStoreModels db = new MusicStoreModels(connStr);

string generName =

(from g in db.Genres

where g.GenreId == gener

select g.Name).First();

 

//查询某类音乐风格的唱片

var albums =

from a in db.Albums

where a.GenreId == gener

select a;

 

ViewData["generName"] = generName;

ViewData["album"] = albums;

return View();

}

}

唱片View

下面的foreach里面的转换就提示: 转换无效

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage" %>

<%@ Import Namespace="MvcApplication.Models" %>

<h2>

音乐分类:<%=ViewData["generName"]%></h2>

<ul>

<%foreach (var album in (IEnumerable<Album>)ViewData["album"])

{%>

<li><%=album.Title %></li>

<%

} %></ul>

有点想不通,一样的代码.一样的类型.怎么就转换无效呢.