Adding a way to prevent content items from being exported

--HG--
branch : 1.x
extra : rebase_source : 259846d236189d44d09f91dce4e154f6b8e3993f

src/Orchard.Web/Core/Contents/Controllers/AdminController.cs

@@ -343,6 +343,13 @@ namespace Orchard.Core.Contents.Controllers {
             var importContentSession = new ImportContentSession(_contentManager);
 
             var element = _contentManager.Export(contentItem);
+
+            // if a handler prevents this element from being exported, it can't be cloned
+            if (element == null) {
+                Services.Notifier.Warning(T("Could not clone the content item."));
+                return this.RedirectLocal(returnUrl, () => RedirectToAction("List"));
+            }
+
             var elementId = element.Attribute("Id");
             var copyId = elementId.Value + "-copy";
             elementId.SetValue(copyId);

src/Orchard/ContentManagement/DefaultContentManager.cs

@@ -703,6 +703,10 @@ namespace Orchard.ContentManagement {
                 contentHandler.Exported(context);
             }
 
+            if (context.Exclude) {
+                return null;
+            }
+
             context.Data.SetAttributeValue("Id", GetItemMetadata(contentItem).Identity.ToString());
             if (contentItem.IsPublished()) {
                 context.Data.SetAttributeValue("Status", Published);

src/Orchard/ContentManagement/Handlers/ExportContentContext.cs

@@ -4,6 +4,11 @@ namespace Orchard.ContentManagement.Handlers {
     public class ExportContentContext : ContentContextBase {
         public XElement Data { get; set; }
 
+        /// <summary>
+        /// Wether the content item should be exclude from the export or not
+        /// </summary>
+        public bool Exclude { get; set; }
+
         public ExportContentContext(ContentItem contentItem, XElement data)
             : base(contentItem) {
             Data = data;