Added some favorites api calls

MediaBrowser.Api/HttpHandlers/FavoriteStatusHandler.cs

@@ -0,0 +1,44 @@
+using MediaBrowser.Common.Net.Handlers;
+using MediaBrowser.Model.DTO;
+using MediaBrowser.Model.Entities;
+using System.ComponentModel.Composition;
+using System.Net;
+using System.Threading.Tasks;
+
+namespace MediaBrowser.Api.HttpHandlers
+{
+    /// <summary>
+    /// Provides a handler to set user favorite status for an item
+    /// </summary>
+    [Export(typeof(BaseHandler))]
+    public class FavoriteStatus : BaseSerializationHandler<DTOUserItemData>
+    {
+        public override bool HandlesRequest(HttpListenerRequest request)
+        {
+            return ApiService.IsApiUrlMatch("FavoriteStatus", request);
+        }
+
+        protected override Task<DTOUserItemData> GetObjectToSerialize()
+        {
+            // Get the item
+            BaseItem item = ApiService.GetItemById(QueryString["id"]);
+
+            // Get the user
+            User user = ApiService.GetUserById(QueryString["userid"], true);
+
+            // Get the user data for this item
+            UserItemData data = item.GetUserData(user);
+
+            if (data == null)
+            {
+                data = new UserItemData();
+                item.AddUserData(user, data);
+            }
+
+            // Set favorite status
+            data.IsFavorite = QueryString["isfavorite"] == "1";
+
+            return Task.FromResult<DTOUserItemData>(ApiService.GetDTOUserItemData(data));
+        }
+    }
+}