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.