C# MVC ASP 3表联接，然后显示结果

对于一个项目，我正在展示用于添加到篮子中的书籍。我需要连接3个表以显示可用的格式：我需要：Books到bookID上的BookFormats，然后BookFormats到formatID上的formats。这是一个我无法更改的预编数据库。我编写了一个LINQ查询来显示它们，并创建了一个包含所有3个属性的视图模型

linq查询：

        IEnumerable<BookAndFormatViewModel> IEBooksRepository.GetAllBooksWithFormats()
    {
        var query =
            from book in eBooks.Books
            join format in eBooks.BookFormats on book.BookID equals format.BookID
            join formatName in eBooks.Formats on format.FormatID equals formatName.FormatID
            select new BookAndFormatViewModel();
        return query.ToList();

    public int BookID { get; set; }
    public string ReferenceNumber { get; set; }
    public string Title { get; set; }
    public decimal Price { get; set; }
    public int FormatID { get; set; }
    public string FormatType { get; set; }

        IEnumerable<BookModel> books = repository.GetAllBooks();
        IEnumerable<BookAndFormatViewModel> booksWithFormat = repository.GetAllBooksWithFormats();

        if (books.Count() == 0)
        {
            return PartialView("NoBooks");

        }
        return PartialView("Books", booksWithFormat);   

控制器代码：

        IEnumerable<BookAndFormatViewModel> IEBooksRepository.GetAllBooksWithFormats()
    {
        var query =
            from book in eBooks.Books
            join format in eBooks.BookFormats on book.BookID equals format.BookID
            join formatName in eBooks.Formats on format.FormatID equals formatName.FormatID
            select new BookAndFormatViewModel();
        return query.ToList();

    public int BookID { get; set; }
    public string ReferenceNumber { get; set; }
    public string Title { get; set; }
    public decimal Price { get; set; }
    public int FormatID { get; set; }
    public string FormatType { get; set; }

        IEnumerable<BookModel> books = repository.GetAllBooks();
        IEnumerable<BookAndFormatViewModel> booksWithFormat = repository.GetAllBooksWithFormats();

        if (books.Count() == 0)
        {
            return PartialView("NoBooks");

        }
        return PartialView("Books", booksWithFormat);   

IEnumerable books=repository.GetAllBooks（）；
IEnumerable booksWithFormat=repository.GetAllBooksWithFormats（）；
如果（books.Count（）==0）
{
返回PartialView（“NoBooks”）；
}
返回PartialView（“Books”，booksWithFormat）；

---

当我运行它时，它只显示空数据0和空字段。

最终的解决方案是更改模型的构造函数，然后像这样创建模型：

            var query =
            from book in eBooks.Books
            join format in eBooks.BookFormats on book.BookID equals format.BookID
            join formatName in eBooks.Formats on format.FormatID equals formatName.FormatID
            select new BookAndFormatViewModel
            {
                BookID = book.BookID,
                ReferenceNumber = book.ReferenceNumber,
                Title = book.Title,
                Price = book.Price,
                FormatID = format.FormatID,
                FormatType = formatName.FormatType
            };

---

此行：

selectnewbookandformatviewmodel（）

正在创建一个空模型，您尚未为属性分配任何值，例如

BookId=book.Id，ReferenceNumber=book.RefNo

etc@markpsmith如果我为构造函数添加了参数，它不会只生成一个条目吗？是否有办法添加每个条目？它将创建一个

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