没有MediaTypeFormatter可用于读取类型的对象

Question

错误是

  

＆＃34;＆＃34;消息＆＃34;：＆＃34;请求包含实体主体但没有Content-Type标头。推断的媒体类型＆＃39; application / octet-stream＆＃39;此资源不支持。＆＃34;，

     

＆＃34; ExceptionMessage＆＃34;：＆＃34;没有MediaTypeFormatter可用于读取类型＆＃39; Expression`1 []＆＃39;来自媒体类型的内容＆＃39; application / octet-stream＆＃39;。＆＃34;，   ＆＃34; ExceptionType＆＃34;：＆＃34; System.Net.Http.UnsupportedMediaTypeException＆＃34;，

     

＆＃34;堆栈跟踪＆＃34;：＆＃34;在System.Net.Http.HttpContentExtensions.ReadAsAsync [T]（HttpContent内容，类型类型，IEnumerable 1 formatters, IFormatterLogger formatterLogger, CancellationToken cancellationToken)\r\n at System.Web.Http.ModelBinding.FormatterParameterBinding.ReadContentAsync(HttpRequestMessage request, Type type, IEnumerable 1格式化程序，IFormatterLogger formatterLogger，CancellationToken cancellationToken）＆＃34;}

我的代码：

public class ParticipantEventController : ApiController
{
    private readonly IParticipantEventRepository repository;


    public ParticipantEventController()
    {
        repository = new ParticipantEventRepository();
    }

    [Route("api/EventDetails/{EventId}")]
    [HttpGet]
     public IEnumerable<EventDTO> GetEventDetails(Guid EventId, params Expression<Func<Event, object>>[] includeProperties)
    {
      IEnumerable<Event> participantevent = repository.FindbyEvent(EventId,x=>x.Id,x=>x.Contents,x=>x.EventRegisteration).ToList();
      var eventdb = Mapper.Map<IEnumerable<EventDTO>>(participantevent);
      return eventdb;

    }
}