LINQ to Objects轉換爲列表以顯示在gridview中

Question

我正在嘗試使用LINQ to Objects將書籍列表綁定到gridview。作者和書籍是自定義對象，其中「作品」在作者類中定義爲列表。

List<Author> authors = new List<Author>(); 
    // list of authors/books is populated here 
    var books = from s in authors 
         where s.LastName == "Jones" 
         select s.Books; 

    GridView2.DataSource = books.AsEnumerable().Cast<Book>().ToList(); 
    GridView2.DataBind(); 

不過，我得到以下錯誤：

System.Web.Services.Protocols.SoapException: Server was unable to process request. --->

System.InvalidCastException: Unable to cast object of type

'System.Collections.Generic.List`1[Book]' to type 'Book'.

at System.Linq.Enumerable.d__aa 1.MoveNext() at System.Collections.Generic.List 1..ctor(IEnumerable 1 collection) at System.Linq.Enumerable.ToList[TSource](IEnumerable 1 source)

我在做什麼錯在這裏？

Answer 1

我認爲問題是，書是一個集合。 所以你實際上得到的書籍集合的集合

// list of authors/books is populated here 
var books = (from s in authors 
        where s.LastName == "Jones" 
        select s.Books).SelectMany(c=>c); 

使用SelectMany 會變成你的藏書收集到的一本書:-)

你也可以replease你Cast用的SelectMany：

var books = from s in authors 
         where s.LastName == "Jones" 
         select s.Books; 

    GridView2.DataSource = books.SelectMany(c => c).ToList(); 
    GridView2.DataBind(); 

Answer 2

這只是一個想法，否則我認爲你很好。 var books =（from s in authors where s.LastName ==「Jones」 select s.Books）.Tolist（）; 並直接傳遞 GridView2.DataSource = books; GridView2.DataBind（）;

這可能工作..