Fixes issue with UmbracoHelper in back office when there is not Document.

Adds another overload to BeginUmbracoForm.

src/Umbraco.Web/HtmlHelperRenderExtensions.cs

@@ -306,6 +306,19 @@ namespace Umbraco.Web
 			return html.BeginUmbracoForm(action, typeof(T), additionalRouteVals, htmlAttributes);
 		}
 
+		/// <summary>
+		/// Helper method to create a new form to execute in the Umbraco request pipeline to a surface controller plugin
+		/// </summary>
+		/// <param name="html"></param>
+		/// <param name="action"></param>
+		/// <param name="controllerName"></param>
+		/// <param name="area"></param>
+		/// <returns></returns>
+		public static MvcForm BeginUmbracoForm(this HtmlHelper html, string action, string controllerName, string area)
+		{
+			return html.BeginUmbracoForm(action, controllerName, area, null, new Dictionary<string, object>());
+		}
+
 		/// <summary>
 		/// Helper method to create a new form to execute in the Umbraco request pipeline to a surface controller plugin
 		/// </summary>

src/Umbraco.Web/Umbraco.Web.csproj

@@ -311,6 +311,7 @@
     <Compile Include="umbraco.presentation\umbraco\nodeFactory\UmbracoSiteMapProviderAccessUpdate.cs" />
     <Compile Include="umbraco.presentation\umbraco\settings\views\editView.aspx.cs">
       <DependentUpon>editView.aspx</DependentUpon>
+      <SubType>ASPXCodeBehind</SubType>
     </Compile>
     <Compile Include="umbraco.presentation\umbraco\uQuery\IGetProperty.cs" />
     <Compile Include="UmbracoHelper.cs" />

src/Umbraco.Web/UmbracoContext.cs

@@ -245,7 +245,7 @@ namespace Umbraco.Web
         /// <summary>
         /// Gets the current page ID, or <c>null</c> if no page ID is available (e.g. a custom page).
         /// </summary>
-        public virtual int? PageId
+        public int? PageId
         {
             get
             {
@@ -265,7 +265,7 @@ namespace Umbraco.Web
         /// Gets the current logged in Umbraco user (editor).
         /// </summary>
         /// <value>The Umbraco user object or null</value>
-        public virtual User UmbracoUser
+        public User UmbracoUser
         {
             get
             {
@@ -277,7 +277,7 @@ namespace Umbraco.Web
         /// <summary>
         /// Determines whether the current user is in a preview mode and browsing the site (ie. not in the admin UI)
         /// </summary>
-        public virtual bool InPreviewMode
+        public bool InPreviewMode
         {
             get
             {

src/Umbraco.Web/UmbracoHelper.cs

@@ -37,8 +37,12 @@ namespace Umbraco.Web
 		internal UmbracoHelper(UmbracoContext umbracoContext)
 		{
 			if (umbracoContext == null) throw new ArgumentNullException("umbracoContext");
+			if (umbracoContext.RoutingContext == null) throw new NullReferenceException("The RoutingContext on the UmbracoContext cannot be null");
 			_umbracoContext = umbracoContext;
-			_currentPage = _umbracoContext.DocumentRequest.Document;
+			if (_umbracoContext.IsFrontEndUmbracoRequest)
+			{
+				_currentPage = _umbracoContext.DocumentRequest.Document;	
+			}
 		}
 
 
@@ -130,6 +134,10 @@ namespace Umbraco.Web
 			RenderFieldEncodingType encoding = RenderFieldEncodingType.Unchanged,
 			string formatString = "")
 		{
+			if (_currentPage == null)
+			{
+				throw new InvalidOperationException("Cannot call this method when not rendering a front-end document");
+			}
 			return Field(_currentPage, fieldAlias, valueAlias, altFieldAlias, altValueAlias,
 				altText, insertBefore, insertAfter, recursive, convertLineBreaks, removeParagraphTags,
 				casing, encoding, formatString);