Question

I am sending a collection of GUID-like objects to my MVC controller like so:

$.ajax({
    type: 'GET',
    url: 'http://localhost:61975/Song/GetByIds',
    dataType: 'json',
    contentType: 'application/json; charset=utf-8',
    data: {
        songIds: JSON.stringify(songIds)
    },
    success: function (data) {
    },
    error: function(error) {
        console.error(error);
    }
});

The data being sent in my request header looks like:

songIds:[“6cb44f55-9fd5-4540-9b11-75ccce816d67”]

and my MVC3 controller method looks like:

[HttpGet]
public ActionResult GetByIds(List<Guid> songIds)
{
    SongManager songManager = new SongManager(SongDao, PlaylistDao, PlaylistItemDao);
    IList<Song> songs = songManager.GetByIds(songIds);
    return new JsonDataContractActionResult(songs);
}

In this implementation I receive a non-null List object, but it is always empty. What’s my mistake?

EDIT: If I POST like this instead of GET it works fine. How come??

$.ajax({
    type: 'POST',
    url: 'http://localhost:61975/Song/GetByIds',
    dataType: 'json',
    contentType: 'application/json; charset=utf-8',
    data: JSON.stringify({
        songIds: songIds
    }),
    success: function (data) {
        loadedSongs = loadedSongs;
        if (callback) {
            callback(data);
        }
    },
    error: function(error) {
        console.error(error);
    }
});

Answer 1

You should try to use “traditional” option set to true for your jQuery Ajax request.

Refer to documentation for more details : http://api.jquery.com/jQuery.ajax/

And you should also remove the JSON.Stringify part.

Can you try this out and let me know if it worked out for you ?
I Did a test on my end and it works just fine.

$.ajax({
    type: 'GET',
    url: 'http://localhost:61975/Song/GetByIds',
    dataType: 'json',
    contentType: 'application/json; charset=utf-8',
    traditional: true, //// traditional option to true
    data: {
       songIds: songIds  /// no JSON.stringify
    },
    success: function (data) {
    },
    error: function(error) {
      console.error(error);
    }
});