500（内部服务器错误）使用API​​ Web服务

Question

我正在尝试从Web API客户端Web服务类调用MVC5 Put方法。我可以通过它的id来编辑本书，但是当我编辑任何内容时，我会收到此错误

  

响应状态代码不表示成功：500（内部服务器错误）。

我已经搜索了一些有关导致此错误的信息，但我无法找到实际问题。有人可以帮忙指出我做错了什么。

API控制器

// PUT: api/Books/5
[ResponseType(typeof(void))]
public async Task<IHttpActionResult> Put(int id, BookDetailDTO book)
{
    try{
        var bookEdit = db.Books.FirstOrDefault(b => b.Id == id);

        if(bookEdit == null){
            return BadRequest();
        }
        else{
            bookEdit.Title = book.Title;
            bookEdit.Year = book.Year;
            bookEdit.Price = book.Price;
            bookEdit.Author.Name = book.AuthorName;
            bookEdit.Genre = book.Genre;
            await db.SaveChangesAsync();

            return CreatedAtRoute("DefaultApi", new { id = book.Id }, bookEdit);
        }
    }
    catch{
        if (!BookExists(id)){
            return NotFound();
        }
        else{
            throw;
        }
    }
}

BookService方法

public void UpdateBook(int? id, BookDetailDTO book)
{
    client.DefaultRequestHeaders.Add("Authorization", "Bearer " + MyToken.myToken);
    BookDetailDTO bookDetailDTO = new BookDetailDTO();

    bookDetailDTO.Id = book.Id;
    bookDetailDTO.Title = book.Title;
    bookDetailDTO.Year = book.Year;
    bookDetailDTO.Genre = book.Genre;
    bookDetailDTO.Price = book.Price;
    bookDetailDTO.AuthorName = book.AuthorName;

    HttpResponseMessage responseMessage = client.PutAsJsonAsync(url + "/" + id, bookDetailDTO).Result;
    responseMessage.EnsureSuccessStatusCode();
}

预订DTO课程

public class BookDetailDTO
{
    public int Id { get; set; }
    public string Title { get; set; }
    public int Year { get; set; }
    public decimal Price { get; set; }
    public string AuthorName { get; set; }
    public string Genre { get; set; }
}   

预订模型

public class Book
{
    public int Id { get; set; }
    [Required]
    public string Title { get; set; }
    public int Year { get; set; }
    public decimal Price { get; set; }
    public string Genre { get; set; }

    // Foreign Key
    public int AuthorId { get; set; }
    //public virtual IEnumerable<Author> AuthorID { get; set; }
    // Navigation property
    public virtual Author Author { get; set; }
}