在ASP.NET應用程序中檢測到無法訪問的代碼

Question

我在ASP.NET應用程序中的搜索方法中收到Visual Studio 2010中的「無法訪問的代碼」消息。 這是方法：

public ActionResult SearchIndex(string artist, string albumGenre, string searchString) 
    { 
     var GenreList = new List<string>(); 

     var GenreQuery = from d in storeDB.Albums orderby d.Genre.Name select   d.Genre.Name; 
     GenreList.AddRange(GenreQuery.Distinct()); 
     ViewBag.albumGenre = new SelectList(GenreList); 

     var ArtistList = new List<string>(); 

     var ArtistQuery = from a in storeDB.Artists orderby a.Name select a.Name; 
     ArtistList.AddRange(ArtistQuery.Distinct()); 
     ViewBag.artist = new SelectList(ArtistList); 

     var albums = from m in storeDB.Albums select m; 

     if (string.IsNullOrEmpty(artist)) 
     { 
      return View(albums); 
     } 
     else 
     { 
      return View(albums.Where(f => f.Artist.Name == artist)); 
     } 

     if (!String.IsNullOrEmpty(searchString)) 
     { 
      return View(albums.Where(s => s.Title.Contains(searchString))); 
     } 

     if (string.IsNullOrEmpty(albumGenre)) 
     { 
      return View(albums); 
     } 
     else 
     { 
      return View(albums.Where(x => x.Genre.Name == albumGenre)); 
     } 
    } 

對於這一說法I'getting消息：

 if (!String.IsNullOrEmpty(searchString)) 
     { 
      return View(albums.Where(s => s.Title.Contains(searchString))); 
     } 

我要去哪裏錯了嗎？

Answer 1

以下是更正代碼

public ActionResult SearchIndex(string artist, string albumGenre, string searchString) 
    { 
     var GenreList = new List<string>(); 

     var GenreQuery = from d in storeDB.Albums orderby d.Genre.Name select   d.Genre.Name; 
     GenreList.AddRange(GenreQuery.Distinct()); 
     ViewBag.albumGenre = new SelectList(GenreList); 

     var ArtistList = new List<string>(); 

     var ArtistQuery = from a in storeDB.Artists orderby a.Name select a.Name; 
     ArtistList.AddRange(ArtistQuery.Distinct()); 
     ViewBag.artist = new SelectList(ArtistList); 

     var albums = from m in storeDB.Albums select m; 

     if (!string.IsNullOrEmpty(artist)) 
     { 
      return View(albums.Where(f => f.Artist.Name == artist)); 
     } 
     else if (!String.IsNullOrEmpty(searchString)) 
     { 
      return View(albums.Where(s => s.Title.Contains(searchString))); 
     } 
     else if (!string.IsNullOrEmpty(albumGenre)) 
     { 
      return View(albums.Where(x => x.Genre.Name == albumGenre)); 
     } 
     else 
     { 
      return View(albums); 
     } 

} 

Answer 2

之前的if在它的兩個分支中都有一個return語句，所以您的函數在到達第二個if之前總會返回。

Answer 3

因爲在之前的if-else塊中，您肯定會返回並放棄您的方法，無論是從if還是從else塊。

因此，您的以下代碼在任何情況下都不會執行。