OutputFormatter XmlDataContractSerializerOutputFormatter asp.net核心未到达子级的子级

我的.Net Core API测试项目包含应以xml格式返回的数据，因此我在Startup类中安装并设置了XmlDataContractSerializerOutputFormatter

services.AddMvc(setupAction => 
            {
                setupAction.ReturnHttpNotAcceptable = true;
                setupAction.OutputFormatters.Add(new XmlDataContractSerializerOutputFormatter()); 
            });

一旦我将Postman中的Accept头设置为application/xml值，数据就会以xml的形式返回，但这只能到达父级和第一个子级，之后，结果是标准的JSON格式。

控制器代码：

namespace Lib.Controllers
{
    [Route("api/authors/{authorId}/books")]
    public class BooksController : Controller
    {
        private ILibraryRepository _libraryRepository;

        public BooksController(ILibraryRepository libraryRepository)
        {
            _libraryRepository = libraryRepository;
        }

        [HttpGet()]
        public IActionResult GetBooksForAuthor(Guid authorId)
        {
            if (!_libraryRepository.AuthorExists(authorId))
            {
                return NotFound();
            }

            var booksForAuthorFromRepo = _libraryRepository.GetBooksForAuthor(authorId);

            var booksForAuthor = AutoMapper.Mapper.Map<IEnumerable<BookDto>>(booksForAuthorFromRepo);

            return Ok(booksForAuthor);
        }

        [HttpGet("{id}")]
        public IActionResult GetBookForAuthor(Guid authorId, Guid Id)
        {
            if (!_libraryRepository.AuthorExists(authorId))
            {
                return NotFound();
            }
            var bookForAuthorFromRepo = _libraryRepository.GetBookForAuthor(authorId, Id);
            if (bookForAuthorFromRepo == null)
            {
                return NotFound("The book does not exist");
            }
            var bookForAuthor = AutoMapper.Mapper.Map<BookDto>(bookForAuthorFromRepo);
            return new JsonResult(bookForAuthor);
        }
    }
}

namespace Lib.Controllers
{
    [Route("api/authors/{authorId}/books")]
    public class BooksController : Controller
    {
        private ILibraryRepository _libraryRepository;

        public BooksController(ILibraryRepository libraryRepository)
        {
            _libraryRepository = libraryRepository;
        }

        [HttpGet()]
        public IActionResult GetBooksForAuthor(Guid authorId)
        {
            if (!_libraryRepository.AuthorExists(authorId))
            {
                return NotFound();
            }

            var booksForAuthorFromRepo = _libraryRepository.GetBooksForAuthor(authorId);

            var booksForAuthor = AutoMapper.Mapper.Map<IEnumerable<BookDto>>(booksForAuthorFromRepo);

            return Ok(booksForAuthor);
        }

        [HttpGet("{id}")]
        public IActionResult GetBookForAuthor(Guid authorId, Guid Id)
        {
            if (!_libraryRepository.AuthorExists(authorId))
            {
                return NotFound();
            }
            var bookForAuthorFromRepo = _libraryRepository.GetBookForAuthor(authorId, Id);
            if (bookForAuthorFromRepo == null)
            {
                return NotFound("The book does not exist");
            }
            var bookForAuthor = AutoMapper.Mapper.Map<BookDto>(bookForAuthorFromRepo);
            return new JsonResult(bookForAuthor);
        }
    }
}

名称空间库控制器
{
[路径（“api/authors/{authorId}/books”）]
公共类控制器：控制器
{
私有ILibraryRepository(ILibraryRepository)；
公共图书管理员（ILibraryRepository libraryRepository）
{
_libraryRepository=libraryRepository；
}
[HttpGet（）]
公共IActionResult GetBooksForAuthor（Guid authorId）
{
if（！\u libraryRepository.AuthorExists（authorId））
{
返回NotFound（）；
}
var booksForAuthorFromRepo=\u libraryRepository.GetBooksForAuthor（authord）；
var booksForAuthor=AutoMapper.Mapper.Map（booksForAuthorFromRepo）；
返回Ok（booksForAuthor）；
}
[HttpGet（“{id}”）]
public IActionResult GetBookForAuthor（Guid authorId，Guid Id）
{
if（！\u libraryRepository.AuthorExists（authorId））
{
返回NotFound（）；
}
var bookForAuthorFromRepo=\u libraryRepository.GetBookForAuthor（authorId，Id）；
if（bookForAuthorFromRepo==null）
{
return NotFound（“该书不存在”）；
}
var bookForAuthor=AutoMapper.Mapper.Map（bookForAuthorFromRepo）；
返回新的JsonResult（bookForAuthor）；
}
}
}

图书管理员代码：

namespace Lib.Controllers
{
    [Route("api/authors/{authorId}/books")]
    public class BooksController : Controller
    {
        private ILibraryRepository _libraryRepository;

        public BooksController(ILibraryRepository libraryRepository)
        {
            _libraryRepository = libraryRepository;
        }

        [HttpGet()]
        public IActionResult GetBooksForAuthor(Guid authorId)
        {
            if (!_libraryRepository.AuthorExists(authorId))
            {
                return NotFound();
            }

            var booksForAuthorFromRepo = _libraryRepository.GetBooksForAuthor(authorId);

            var booksForAuthor = AutoMapper.Mapper.Map<IEnumerable<BookDto>>(booksForAuthorFromRepo);

            return Ok(booksForAuthor);
        }

        [HttpGet("{id}")]
        public IActionResult GetBookForAuthor(Guid authorId, Guid Id)
        {
            if (!_libraryRepository.AuthorExists(authorId))
            {
                return NotFound();
            }
            var bookForAuthorFromRepo = _libraryRepository.GetBookForAuthor(authorId, Id);
            if (bookForAuthorFromRepo == null)
            {
                return NotFound("The book does not exist");
            }
            var bookForAuthor = AutoMapper.Mapper.Map<BookDto>(bookForAuthorFromRepo);
            return new JsonResult(bookForAuthor);
        }
    }
}

namespace Lib.Controllers
{
    [Route("api/authors/{authorId}/books")]
    public class BooksController : Controller
    {
        private ILibraryRepository _libraryRepository;

        public BooksController(ILibraryRepository libraryRepository)
        {
            _libraryRepository = libraryRepository;
        }

        [HttpGet()]
        public IActionResult GetBooksForAuthor(Guid authorId)
        {
            if (!_libraryRepository.AuthorExists(authorId))
            {
                return NotFound();
            }

            var booksForAuthorFromRepo = _libraryRepository.GetBooksForAuthor(authorId);

            var booksForAuthor = AutoMapper.Mapper.Map<IEnumerable<BookDto>>(booksForAuthorFromRepo);

            return Ok(booksForAuthor);
        }

        [HttpGet("{id}")]
        public IActionResult GetBookForAuthor(Guid authorId, Guid Id)
        {
            if (!_libraryRepository.AuthorExists(authorId))
            {
                return NotFound();
            }
            var bookForAuthorFromRepo = _libraryRepository.GetBookForAuthor(authorId, Id);
            if (bookForAuthorFromRepo == null)
            {
                return NotFound("The book does not exist");
            }
            var bookForAuthor = AutoMapper.Mapper.Map<BookDto>(bookForAuthorFromRepo);
            return new JsonResult(bookForAuthor);
        }
    }
}

名称空间库控制器
{
[路径（“api/authors/{authorId}/books”）]
公共类控制器：控制器
{
私有ILibraryRepository(ILibraryRepository)；
公共图书管理员（ILibraryRepository libraryRepository）
{
_libraryRepository=libraryRepository；
}
[HttpGet（）]
公共IActionResult GetBooksForAuthor（Guid authorId）
{
if（！\u libraryRepository.AuthorExists（authorId））
{
返回NotFound（）；
}
var booksForAuthorFromRepo=\u libraryRepository.GetBooksForAuthor（authord）；
var booksForAuthor=AutoMapper.Mapper.Map（booksForAuthorFromRepo）；
返回Ok（booksForAuthor）；
}
[HttpGet（“{id}”）]
public IActionResult GetBookForAuthor（Guid authorId，Guid Id）
{
if（！\u libraryRepository.AuthorExists（authorId））
{
返回NotFound（）；
}
var bookForAuthorFromRepo=\u libraryRepository.GetBookForAuthor（authorId，Id）；
if（bookForAuthorFromRepo==null）
{
return NotFound（“该书不存在”）；
}
var bookForAuthor=AutoMapper.Mapper.Map（bookForAuthorFromRepo）；
返回新的JsonResult（bookForAuthor）；
}
}
}

将返回类型从JsonResult（）更改为Ok（）解决了问题。

---

感谢@PanagiotisKanavos

发布相关代码-控制器、操作以及创建和返回响应数据的代码。屏幕截图没有显示与问题相关的任何内容-它们显示了两个不同的请求，而不是一个包含子项的XML文档。原始响应是什么？@PanagiotisKanavos这是原始响应

{“id”：“c7ba6add-09c4-45f8-8dd0-eaca221e5d93”，“title”：“The Shining”，“description”：“光辉是美国作家斯蒂芬·金（Stephen King）的一部恐怖小说。1977年出版，这是金的第三部出版的小说，也是第一本精装本畅销书：这本书的成功使金成为恐怖流派中杰出的作家。”，“authorId”：“25320c5e-f58a-4b1f-b63a-8ee07a840bdf”

返回新的JsonResult

？@PanagiotisKanavos谢谢，将返回结果更改为

返回Ok

解决了问题。