1 files changed, 43 insertions, 0 deletions
diff --git a/MediaBrowser.Common/Mef/MefUtils.cs b/MediaBrowser.Common/Mef/MefUtils.cs
new file mode 100644
index 000000000..55d888697
--- /dev/null
+++ b/MediaBrowser.Common/Mef/MefUtils.cs
@@ -0,0 +1,43 @@
+using System.Collections.Generic;
+using System.ComponentModel.Composition.Hosting;
+using System.ComponentModel.Composition.Primitives;
+using System.Linq;
+using System.Reflection;
+
+namespace MediaBrowser.Common.Mef
+{
+    public static class MefUtils
+    {
+        /// <summary>
+        /// Plugins that live on both the server and UI are going to have references to assemblies from both sides.
+        /// But looks for Parts on one side, it will throw an exception when it seems Types from the other side that it doesn't have a reference to.
+        /// For example, a plugin provides a Resolver. When MEF runs in the UI, it will throw an exception when it sees the resolver because there won't be a reference to the base class.
+        /// This method will catch those exceptions while retining the list of Types that MEF is able to resolve.
+        /// </summary>
+        public static CompositionContainer GetSafeCompositionContainer(IEnumerable<ComposablePartCatalog> catalogs)
+        {
+            var newList = new List<ComposablePartCatalog>();
+
+            // Go through each Catalog
+            foreach (var catalog in catalogs)
+            {
+                try
+                {
+                    // Try to have MEF find Parts
+                    catalog.Parts.ToArray();
+
+                    // If it succeeds we can use the entire catalog
+                    newList.Add(catalog);
+                }
+                catch (ReflectionTypeLoadException ex)
+                {
+                    // If it fails we can still get a list of the Types it was able to resolve and create TypeCatalogs
+                    var typeCatalogs = ex.Types.Where(t => t != null).Select(t => new TypeCatalog(t));
+                    newList.AddRange(typeCatalogs);
+                }
+            }
+
+            return new CompositionContainer(new AggregateCatalog(newList));
+        }
+    }
+}