Got further with pre-value editors and strongly typed stuff, got the pre-value editor for drop down list working and saving array objects. Now need to wire that up to the editor but think i need to change how the drop down list displays it's values.

src/Umbraco.Core/Models/Editors/ContentPropertyData.cs

@@ -22,6 +22,8 @@ namespace Umbraco.Core.Models.Editors
             AdditionalData = new ReadOnlyDictionary<string, object>(additionalData);
         }
 
+        //TODO: Change this to an object so we can post JSON or json converted clr types if we want!
+
         /// <summary>
         /// The string value submitted for the property
         /// </summary>

src/Umbraco.Core/PropertyEditors/PreValueEditor.cs

@@ -102,9 +102,10 @@ namespace Umbraco.Core.PropertyEditors
         /// This can be overridden if perhaps you have a comma delimited string posted value but want to convert those to individual rows, or to convert
         /// a json structure to multiple rows.
         /// </remarks>
-        public virtual IDictionary<string, string> FormatDataForPersistence(IDictionary<string, string> editorValue, PreValueCollection currentValue)
+        public virtual IDictionary<string, string> FormatDataForPersistence(IDictionary<string, object> editorValue, PreValueCollection currentValue)
         {
-            return editorValue;
+            //convert to a string based value to be saved in the db
+            return editorValue.ToDictionary(x => x.Key, x => x.Value == null ? null : x.Value.ToString());
         }
 
         /// <summary>

src/Umbraco.Core/PropertyEditors/ValueEditor.cs

@@ -171,6 +171,8 @@ namespace Umbraco.Core.PropertyEditors
             return result.Result;
         }
 
+        //TODO: Change the result to object so we can pass back JSON or json converted clr types if we want!
+
         /// <summary>
         /// A method used to serialize the databse value to a string value which is then used to be sent
         /// to the editor in JSON format.

src/Umbraco.Web.UI.Client/src/common/directives/valHighlight.directive.js

@@ -0,0 +1,30 @@
+/**
+* @ngdoc directive
+* @name umbraco.directives.directive:valHighlight
+* @restrict A
+* @description Used on input fields when you want to signal that they are in error, this will highlight the item for 1 second
+**/
+function valHighlight($timeout) {
+    return {
+        restrict: "A",
+        link: function (scope, element, attrs, ctrl) {
+            
+            scope.$watch(function() {
+                return scope.$eval(attrs.valHighlight);
+            }, function(newVal, oldVal) {
+                if (newVal === true) {
+                    element.addClass("highlight-error");
+                    $timeout(function () {
+                        //set the bound scope property to false
+                        scope[attrs.valHighlight] = false;
+                    }, 1000);
+                }
+                else {
+                    element.removeClass("highlight-error");
+                }
+            });
+   
+        }
+    };
+}
+angular.module('umbraco.directives').directive("valHighlight", valHighlight);

src/Umbraco.Web.UI.Client/src/less/forms.less

@@ -399,6 +399,16 @@ input[type="checkbox"][readonly] {
 }
 
 
+input.highlight-error,
+select.highlight-error,
+textarea.highlight-error {
+  border-color: #953b39 !important;
+  -webkit-box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075), 0 0 6px #d59392;
+     -moz-box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075), 0 0 6px #d59392;
+          box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075), 0 0 6px #d59392;
+}
+
+
 // FORM ACTIONS
 // ------------
 

src/Umbraco.Web.UI.Client/src/less/mixins.less

@@ -198,9 +198,6 @@
   }
 }
 
-
-
-
 // CSS3 PROPERTIES
 // --------------------------------------------------
 

src/Umbraco.Web.UI.Client/src/views/propertyeditors/dropdown/dropdown.prevalue.controller.js

@@ -0,0 +1,33 @@
+angular.module("umbraco").controller("Umbraco.Editors.DropdownPreValueController",
+    function ($scope, $timeout) {
+       
+        $scope.newItem = "";
+        $scope.hasError = false;
+
+        $scope.remove = function(item, evt) {
+
+            evt.preventDefault();
+
+            $scope.model.value = _.reject($scope.model.value, function(i) {
+                return i === item;
+            });
+        };
+
+        $scope.add = function (evt) {
+            
+            evt.preventDefault();
+            
+            if (!_.contains($scope.model.value, $scope.newItem)) {
+                if ($scope.newItem) {
+                    $scope.model.value.push($scope.newItem);
+                    $scope.newItem = "";
+                    $scope.hasError = false;
+                    return;
+                }
+            }
+
+            //there was an error, do the highlight (will be set back by the directive)
+            $scope.hasError = true;            
+        };
+
+    });

src/Umbraco.Web.UI.Client/src/views/propertyeditors/dropdown/dropdown.prevalue.html

@@ -1,5 +1,13 @@
-<div>
-    
-    <input type="text" ng-model="model.value" />
+<div ng-controller="Umbraco.Editors.DropdownPreValueController">
+    <ul class="unstyled">
+        <li>
+            <input name="newItem" type="text" ng-model="newItem" val-highlight="hasError" />
+            <button class="btn" ng-click="add($event)">Add</button>
+        </li>
+        <li ng-repeat="item in model.value">
+            <input type="text" ng-model="item" />
+            <button class="btn" ng-click="remove(item, $event)">Remove</button>
+        </li>
+    </ul>
 </div>
  

src/Umbraco.Web/Editors/DataTypeValidateAttribute.cs

@@ -88,7 +88,7 @@ namespace Umbraco.Web.Editors
 
                 foreach (var v in propertyEditor.PreValueEditor.Fields.SelectMany(x => x.Validators))
                 {
-                    foreach (var result in v.Validate(postedValue, preVal.Key, propertyEditor))
+                    foreach (var result in v.Validate(postedValue != null ? postedValue.ToString() : null, preVal.Key, propertyEditor))
                     {
                         //if there are no member names supplied then we assume that the validation message is for the overall property
                         // not a sub field on the property editor

src/Umbraco.Web/Models/ContentEditing/PreValueFieldSave.cs

@@ -18,6 +18,6 @@ namespace Umbraco.Web.Models.ContentEditing
         /// The value stored for the pre-value field
         /// </summary>
         [DataMember(Name = "value", IsRequired = true)]
-        public string Value { get; set; }
+        public object Value { get; set; }
     }
 }

src/Umbraco.Web/Models/Mapping/PreValueDisplayResolver.cs

@@ -70,7 +70,7 @@ namespace Umbraco.Web.Models.Mapping
                         LogHelper.Warn<PreValueDisplayResolver>("Could not find persisted pre-value for field " + field.Key);
                         continue;
                     }
-                    field.Value = dictionaryVals.Single(x => x.Key.InvariantEquals(field.Key)).Value.ToString();
+                    field.Value = dictionaryVals.Single(x => x.Key.InvariantEquals(field.Key)).Value;
                 }
 
 

src/Umbraco.Web/PropertyEditors/DropDownPreValueEditor.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
 using Umbraco.Core;
 using Umbraco.Core.Logging;
 using Umbraco.Core.Models;
@@ -23,9 +24,9 @@ namespace Umbraco.Web.PropertyEditors
         {
             var dictionary = PreValueCollection.AsDictionary(persistedPreVals);
             var arrayOfVals = dictionary.Select(item => item.Value).ToList();
-            var json = JsonConvert.SerializeObject(arrayOfVals);
+            //var json = JsonConvert.SerializeObject(arrayOfVals);
 
-            return new Dictionary<string, object> {{"temp", json}};
+            return new Dictionary<string, object> { { "temp", arrayOfVals } };
         }
 
         /// <summary>
@@ -33,23 +34,28 @@ namespace Umbraco.Web.PropertyEditors
         /// </summary>
         /// <param name="editorValue"></param>
         /// <param name="currentValue"></param>
-        /// <returns></returns>
+        /// <returns>
+        /// A string/string dictionary since all values that need to be persisted in the database are strings.
+        /// </returns>
         /// <remarks>
         /// This is mostly because we want to maintain compatibility with v6 drop down property editors that store their prevalues in different db rows.
         /// </remarks>
-        public override IDictionary<string, string> FormatDataForPersistence(IDictionary<string, string> editorValue, Core.Models.PreValueCollection currentValue)
+        public override IDictionary<string, string> FormatDataForPersistence(IDictionary<string, object> editorValue, PreValueCollection currentValue)
         {
-            var val = editorValue["temp"];
+            var val = editorValue["temp"] as JArray;
             var result = new Dictionary<string, string>();
-            if (val.IsNullOrWhiteSpace()) return result;
+            
+            if (val == null)
+            {
+                return result;
+            }
 
             try
             {
-                var deserialized = JsonConvert.DeserializeObject<string[]>(val);
                 var index = 0;
-                foreach (var item in deserialized)
+                foreach (var item in val)
                 {
-                    result.Add(index.ToInvariantString(), item);
+                    result.Add(index.ToInvariantString(), item.ToString());
                     index++;
                 }
             }