Merge pull request #2659 from jamescoxhead/U4-11272

U4-11272 Added flexible dropdown property value converter

src/Umbraco.Core/PropertyEditors/ValueConverters/FlexibleDropdownPropertyValueConverter.cs

@@ -0,0 +1,137 @@
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Linq;
+using Umbraco.Core.Models.PublishedContent;
+using Umbraco.Core.Services;
+
+namespace Umbraco.Core.PropertyEditors.ValueConverters
+{
+    [DefaultPropertyValueConverter]
+    public class FlexibleDropdownPropertyValueConverter : PropertyValueConverterBase, IPropertyValueConverterMeta
+    {
+        private static readonly ConcurrentDictionary<int, bool> Storages = new ConcurrentDictionary<int, bool>();
+        private readonly IDataTypeService _dataTypeService;
+
+        // TODO: Remove this ctor in v8 - the other one will be usable via IoC
+        public FlexibleDropdownPropertyValueConverter() : this(ApplicationContext.Current.Services.DataTypeService)
+        { }
+
+        public FlexibleDropdownPropertyValueConverter(IDataTypeService dataTypeService)
+        {
+            Mandate.ParameterNotNull(dataTypeService, "dataTypeService");
+            _dataTypeService = dataTypeService;
+        }
+
+        public override bool IsConverter(PublishedPropertyType propertyType)
+        {
+            return propertyType.PropertyEditorAlias.Equals(Constants.PropertyEditors.DropDownListFlexibleAlias);
+        }
+
+        public override object ConvertDataToSource(PublishedPropertyType propertyType, object source, bool preview)
+        {
+            return source != null
+                       ? source.ToString().Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries)
+                       : null;
+        }
+
+        public override object ConvertSourceToObject(PublishedPropertyType propertyType, object source, bool preview)
+        {
+            if (source == null)
+            {
+                return null;
+            }
+
+            var selectedValues = (string[]) source;
+            if (selectedValues.Any())
+            {
+                if (IsMultipleDataType(propertyType.DataTypeId, propertyType.PropertyEditorAlias))
+                {
+                    return selectedValues;
+                }
+
+                return selectedValues.First();
+            }
+
+            return source;
+        }
+
+        public Type GetPropertyValueType(PublishedPropertyType propertyType)
+        {
+            return IsMultipleDataType(propertyType.DataTypeId, propertyType.PropertyEditorAlias)
+                       ? typeof(IEnumerable<string>)
+                       : typeof(string);
+        }
+
+        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>
+        /// Determines if the "enable multiple choice" prevalue has been ticked.
+        /// </summary>
+        /// <param name="dataTypeId">The ID of this particular datatype instance.</param>
+        /// <param name="propertyEditorAlias">The property editor alias.</param>
+        /// <returns><value>true</value> if the data type has been configured to return multiple values.
+        /// </returns>
+        private bool IsMultipleDataType(int dataTypeId, string propertyEditorAlias)
+        {
+            // GetPreValuesCollectionByDataTypeId is cached at repository level;
+            // still, the collection is deep-cloned so this is kinda expensive,
+            // better to cache here + trigger refresh in DataTypeCacheRefresher
+            return Storages.GetOrAdd(dataTypeId, id =>
+            {
+                var preVals = _dataTypeService.GetPreValuesCollectionByDataTypeId(id).PreValuesAsDictionary;
+
+                if (preVals.ContainsKey("multiple"))
+                {
+                    var preValue = preVals
+                                   .FirstOrDefault(x => string.Equals(x.Key, "multiple",
+                                                                      StringComparison.InvariantCultureIgnoreCase))
+                                   .Value;
+
+                    return preValue != null && preValue.Value.TryConvertTo<bool>().Result;
+                }
+
+                //in some odd cases, the pre-values in the db won't exist but their default pre-values contain this key so check there 
+                var propertyEditor = PropertyEditorResolver.Current.GetByAlias(propertyEditorAlias);
+                if (propertyEditor != null)
+                {
+                    var preValue = propertyEditor.DefaultPreValues
+                                                 .FirstOrDefault(x => string.Equals(x.Key, "multiple",
+                                                                                    StringComparison
+                                                                                        .InvariantCultureIgnoreCase))
+                                                 .Value;
+
+                    return preValue != null && preValue.TryConvertTo<bool>().Result;
+                }
+
+                return false;
+            });
+        }
+
+        internal static void ClearCaches()
+        {
+            Storages.Clear();
+        }
+    }
+}