AnonymousType无法序列化。 考虑使用DataContractAttribute属性对其进行标记

Question

I have a Web API and I'm just trying to return some data to the calling client in XML format.

I keep getting the following error:

<ExceptionMessage>
Type '<>f__AnonymousType7`9[System.String,System.String,System.String,System.String,System.String,System.String,System.String,System.Nullable`1[System.Int32],System.String]' cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute. If the type is a collection, consider marking it with the CollectionDataContractAttribute. See the Microsoft .NET Framework documentation for other supported types.
</ExceptionMessage>

Here's the Controller code:

public class TribuneShowsController : ApiController
    {
        private readonly TVDataEntities db;

        public TribuneShowsController()
        {
            db = new TVDataEntities();
            db.Configuration.ProxyCreationEnabled = false;
        }

        public IEnumerable GetTribuneShows(string title = null,
                                           string genre = null,
                                           string showTypeDescription = null,
                                           string directorName = null,
                                           string releaseYear = null)
        {
            var query = from shows in db.TRIB_Shows
                        from showTypes in
                            db.TRIB_LKP_ShowTypes.Where(v => v.ShowTypeCode == shows.ShowTypeCode).DefaultIfEmpty()
                        select new
                            {
                                dataSource = "Tribune",
                                shows.Title,
                                EpisodeId = "",
                                EpisodeTitle = "",
                                Genre = shows.Category,
                                showTypes.ShowTypeDescription,
                                shows.DirectorName,
                                shows.ReleaseYear,
                                SeasonEpisode = ""
                            };

            if (title != null)
            {
                query = query.Where(s => s.Title.Contains(title));
            }

            if (genre != null)
            {
                query = query.Where(s => s.Genre.Contains(genre));
            }

            if (showTypeDescription != null)
            {
                query = query.Where(s => s.ShowTypeDescription.Contains(showTypeDescription));
            }

            if (directorName != null)
            {
                query = query.Where(s => s.DirectorName.Contains(directorName));
            }

            if (releaseYear != null)
            {
                query = query.Where(s => s.ReleaseYear.ToString().Contains(releaseYear));
            }

            return query.ToList();
        }

        protected override void Dispose(bool disposing)
        {
            db.Dispose();
            base.Dispose(disposing);
        }
    }

My first question is, how do I default the return object (by the API) to XML? So whenever someone goes to the link, they'll get an XML.

Second question is, how do I go about returning the anonymous type in my code above as an XML to the client?

Answer 1

Give the type a name so it's no longer anonymous:

[DataContract]
public class Show
{
     public string DataSource {get; set;}
     public string Title {get; set;}
  ... etc.
}

then

select new Show
    {
        DataSource = "Tribune",
        Title = shows.Title,
        EpisodeId = "",
        EpisodeTitle = "",
        Genre = shows.Category,
        ShowTypeDescription = showTypes.ShowTypeDescription,
        DirectorName = shows.DirectorName,
        ReleaseYear = shows.ReleaseYear,
        SeasonEpisode = ""
    };

Answer 2

Just make a type and select new instances of that type instead of an anonymous object.

As for the XML type... you don't want to do that. The beauty of the ApiController is that it will serialize to whatever type the client wants. If they say Accept: text/xml they will get xml. If they say Accept: text/json they will get JSON.