Check if MediaPicker is configured as single or multiple and give back appropriate result for each (IPublishedContent vs IEnumerable<IPublishedContent>)

src/Umbraco.Web/PropertyEditors/ValueConverters/MediaPickerPropertyConverter.cs

@@ -8,8 +8,10 @@
 // --------------------------------------------------------------------------------------------------------------------
 
 using System;
-
+using System.Collections.Generic;
+using System.Linq;
 using Umbraco.Core;
+using Umbraco.Core.Logging;
 using Umbraco.Core.Models;
 using Umbraco.Core.Models.PublishedContent;
 using Umbraco.Core.PropertyEditors;
@@ -21,12 +23,72 @@ namespace Umbraco.Web.PropertyEditors.ValueConverters
     /// The media picker property value converter.
     /// </summary>
     [DefaultPropertyValueConverter]
-    [PropertyValueType(typeof(IPublishedContent))]
-    [PropertyValueCache(PropertyCacheValue.Object, PropertyCacheLevel.ContentCache)]
-    [PropertyValueCache(PropertyCacheValue.Source, PropertyCacheLevel.Content)]
-    [PropertyValueCache(PropertyCacheValue.XPath, PropertyCacheLevel.Content)]
-    public class MediaPickerPropertyConverter : PropertyValueConverterBase
+    public class MediaPickerPropertyConverter : PropertyValueConverterBase, IPropertyValueConverterMeta
     {
+        public Type GetPropertyValueType(PublishedPropertyType propertyType)
+        {
+            return IsMultipleDataType(propertyType.DataTypeId) ? typeof(IEnumerable<IPublishedContent>) : typeof(IPublishedContent);
+        }
+
+        public PropertyCacheLevel GetPropertyCacheLevel(PublishedPropertyType propertyType, PropertyCacheValue cacheValue)
+        {
+            PropertyCacheLevel returnLevel;
+            switch (cacheValue)
+            {
+                case PropertyCacheValue.Object:
+                    returnLevel = PropertyCacheLevel.ContentCache;
+                    break;
+                case PropertyCacheValue.Source:
+                    returnLevel = PropertyCacheLevel.Content;
+                    break;
+                case PropertyCacheValue.XPath:
+                    returnLevel = PropertyCacheLevel.Content;
+                    break;
+                default:
+                    returnLevel = PropertyCacheLevel.None;
+                    break;
+            }
+
+            return returnLevel;
+        }
+
+        /// <summary>
+        /// The is multiple data type.
+        /// </summary>
+        /// <param name="dataTypeId">
+        /// The data type id.
+        /// </param>
+        /// <returns>
+        /// The <see cref="bool"/>.
+        /// </returns>
+        private bool IsMultipleDataType(int dataTypeId)
+        {
+            var multipleItems = false;
+
+            try
+            {
+                var dts = ApplicationContext.Current.Services.DataTypeService;
+
+                var multiPickerPreValues =
+                    dts.GetPreValuesCollectionByDataTypeId(dataTypeId).PreValuesAsDictionary;
+
+                var multiPickerPreValue = multiPickerPreValues.FirstOrDefault(x => string.Equals(x.Key, "multiPicker", StringComparison.InvariantCultureIgnoreCase)).Value;
+
+                var attemptConvert = multiPickerPreValue.Value.TryConvertTo<bool>();
+
+                if (attemptConvert.Success)
+                {
+                    multipleItems = attemptConvert.Result;
+                }
+            }
+            catch (Exception ex)
+            {
+                LogHelper.Error<MediaPickerPropertyConverter>(string.Format("Error finding multipleItems data type prevalue on data type Id {0}", dataTypeId), ex);
+            }
+
+            return multipleItems;
+        }
+
         /// <summary>
         /// Checks if this converter can convert the property editor and registers if it can.
         /// </summary>
@@ -62,13 +124,11 @@ namespace Umbraco.Web.PropertyEditors.ValueConverters
         /// </returns>
         public override object ConvertDataToSource(PublishedPropertyType propertyType, object source, bool preview)
         {
-            var attemptConvertInt = source.TryConvertTo<int>();
-            if (attemptConvertInt.Success)
-                return attemptConvertInt.Result;
-            var attemptConvertUdi = source.TryConvertTo<Udi>();
-            if (attemptConvertUdi.Success)
-                return attemptConvertUdi.Result;
-            return null;
+            var nodeIds = source.ToString()
+                .Split(new[] { "," }, StringSplitOptions.RemoveEmptyEntries)
+                .Select(Udi.Parse)
+                .ToArray();
+            return nodeIds;
         }
 
         /// <summary>
@@ -93,12 +153,24 @@ namespace Umbraco.Web.PropertyEditors.ValueConverters
                 return null;
             }
 
-            Udi udi;
-            if (Udi.TryParse(source.ToString(), out udi))
+            var udis = (Udi[])source;
+            var mediaItems = new List<IPublishedContent>();
+            if (udis.Any())
             {
-                var media = udi.ToPublishedContent();
-                if (media != null)
-                    return media;
+                foreach (var udi in udis)
+                {
+                    var item = udi.ToPublishedContent();
+                    if (item != null)
+                        mediaItems.Add(item);
+                }
+                if (IsMultipleDataType(propertyType.DataTypeId))
+                {
+                    return mediaItems;
+                }
+                else
+                {
+                    return mediaItems.FirstOrDefault();
+                }
             }
 
             return source;