asp.net – 从Web API获取空的500 http状态代码

根据this article中给出的建议,我使用了DataContractAttribute并在所有成员上设置了IsReference = true.我还在我要序列化的所有属性上提供了DataMemberAttribute.

为了确保序列化程序不再出现任何问题,我只选择不序列化导航属性.

但是,我的catch块中仍然遇到异常.例外的细节如下：

_innerException: {"Type 
'System.Data.Entity.DynamicProxies.Author_615FB9F8BB22B55A7CA168DA5ED29EC6A0B59F62FD79D1346045351BE2F163A4' with data contract name 
    'Author_615FB9F8BB22B55A7CA168DA5ED29EC6A0B59F62FD79D1346045351BE2F163A4:
http://schemas.datacontract
    .org/2004/07/System.Data.Entity.DynamicProxies' is not expected. 
Consider using a 
    DataContractResolver or add any types not known statically to 
the list of known types - for 
    example,by using the KnownTypeAttribute attribute or by adding them 
to the list of known types 
    passed to DataContractSerializer."}

我可以但不希望：

1)禁用代理创建.我可以删除代理创建只是为了序列化,我可能会这样做.但我也想知道为什么我仍然得到例外以及我能做些什么.

2)删除循环引用.原因：这些类型的引用在Entity Framework生成的模型中非常常见.如果我要在模型中做一个800 – 1000个类的大项目,那么通过删除循环引用来实现它是一个噩梦.

我在下面描述了这个小尖峰解决方案的架构元素.

数据库架构

Id  AuthorName
-------------------------------
1   Charles Dickens
2   Charles Petzold
3   Charles Darwin
4   Charles Chaplin
5   Leo Tolstoy
6   Fydor Dostoevsky
7   Ayn Rand
8   Napolean Hill
9   Claude M. Bristol
10  Edward Dwight Easty
11  O. Henry
12  William Shakespeare
13  Juwal Lowy
14  Jeffrey Richter
15  Chris Sells
16  Don Box
17  Steven Pinker
18  Jim Rohn
19  George Eliot
20  Sathyaish Chakravarthy



Id          Title                                              AuthorId
----------- -------------------------------------------------- -----------
1           Nicholas Nickleby                                  1


Id          BookId      Review
----------- ---------------------------------------------------------------
1           1           How do I know? I haven't read it.

模型

using System.Collections.Generic;
using System.Runtime.Serialization;

namespace BookReviewsModel
{
    [DataContract(IsReference = true)]
    public partial class Author
    {
        [DataMember]
        public virtual int Id { get; set; }

        [DataMember]
        public virtual string AuthorName { get; set; }

        public virtual ICollection<Book> Books { get; set; }
    }
}


namespace BookReviewsModel
{
    [DataContract(IsReference = true)]
    public partial class Book
    {
        [DataMember]
        public virtual int Id { get; set; }

        [DataMember]
        public virtual string Title { get; set; }

        [DataMember]
        public virtual int AuthorId { get; set; }

        public virtual Author Author { get; set; }

        public virtual ICollection<BookReview> BookReviews {  get; set; }
    }
}

namespace BookReviewsModel
{
    [DataContract(IsReference = true)]
    public partial class BookReview
    {
        [DataMember]
        public virtual int Id { get; set; }

        [DataMember]
        public virtual int BookId { get; set; }

        [DataMember]
        [AllowHtml]
        public virtual string Review { get; set; }

        public virtual Book Book { get; set; }
    }
}

控制器代码

namespace BookReviews.Controllers
{
    public class AuthorController : ApiController
    {
        [HttpGet]
        public IEnumerable<Author> Index()
        {
            try
            {
                using (var context = new BookReviewEntities())
                {
                    var authors = context.Authors.ToList();

                    var str = Serialize(new XmlMediaTypeFormatter(),authors);

                    System.Diagnostics.Debugger.Break();
                    System.Diagnostics.Debug.Print(str);

                    return authors;
                }
            }
            catch (Exception ex)
            {
                var responseMessage = new HttpResponseMessage
                {
                    Content = new StringContent("Couldn't retreive the list of authors."),ReasonPhrase = ex.Message.Replace('n',' ')
                };

                throw new HttpResponseException(responseMessage);
            }
        }

        string Serialize<T>(MediaTypeFormatter formatter,T value)
        {
            Stream stream = new MemoryStream();
            var content = new StreamContent(stream);

            formatter.WriteToStreamAsync(typeof(T),value,stream,content,null).Wait();

            stream.Position = 0;
            return content.ReadAsStringAsync().Result;
        }
    }
}