From 7fae24634142a50688de478a2db105ff4b6fcf69 Mon Sep 17 00:00:00 2001
From: Sipke Schoorstra <sipke@ideliverable.com>
Date: Sun, 23 Aug 2015 22:40:34 +0100
Subject: [PATCH] Added convenience overload taking a default value factory
 method.

This overload is useful in scenarios where you want to provide a default value but is relatively expensive to execute.
Using the overload, the factory method is only executed if the infoset does not contain an entry for the requested key.
---
 src/Orchard/ContentManagement/InfosetHelper.cs | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/Orchard/ContentManagement/InfosetHelper.cs b/src/Orchard/ContentManagement/InfosetHelper.cs
index 379c2a665..9b7cae247 100644
--- a/src/Orchard/ContentManagement/InfosetHelper.cs
+++ b/src/Orchard/ContentManagement/InfosetHelper.cs
@@ -10,19 +10,26 @@ namespace Orchard.ContentManagement {
 
         public static TProperty Retrieve<TPart, TProperty>(this TPart contentPart,
             Expression<Func<TPart, TProperty>> targetExpression,
-            TProperty defaultValue = default(TProperty),
+            Func<TProperty> defaultValue,
             bool versioned = false) where TPart : ContentPart {
 
             var propertyInfo = ReflectionHelper<TPart>.GetPropertyInfo(targetExpression);
             var name = propertyInfo.Name;
-
             var infosetPart = contentPart.As<InfosetPart>();
             var el = infosetPart == null
                 ? null
                 : (versioned ? infosetPart.VersionInfoset.Element : infosetPart.Infoset.Element)
                 .Element(contentPart.GetType().Name);
             var attr = el != null ? el.Attribute(name) : default(XAttribute);
-            return attr == null ? defaultValue : XmlHelper.Parse<TProperty>(attr.Value);
+            return attr == null ? defaultValue != null ? defaultValue() : default(TProperty) : XmlHelper.Parse<TProperty>(attr.Value);
+        }
+
+        public static TProperty Retrieve<TPart, TProperty>(this TPart contentPart,
+            Expression<Func<TPart, TProperty>> targetExpression,
+            TProperty defaultValue = default(TProperty),
+            bool versioned = false) where TPart : ContentPart {
+
+            return Retrieve(contentPart, targetExpression, () => defaultValue, versioned);
         }
 
         public static TProperty Retrieve<TProperty>(this ContentPart contentPart, string name,