Add a custom content item binder for saving blueprints (fixes #2985)

src/Umbraco.Web/Editors/ContentController.cs

@@ -576,7 +576,7 @@ namespace Umbraco.Web.Editors
         [FileUploadCleanupFilter]
         [ContentPostValidate]
         public ContentItemDisplay PostSaveBlueprint(
-            [ModelBinder(typeof(ContentItemBinder))] ContentItemSave contentItem)
+            [ModelBinder(typeof(BlueprintItemBinder))] ContentItemSave contentItem)
         {
             var contentItemDisplay = PostSaveInternal(contentItem,
                 content =>

src/Umbraco.Web/Umbraco.Web.csproj

@@ -823,6 +823,7 @@
     </Compile>
     <Compile Include="WebApi\AngularJsonMediaTypeFormatter.cs" />
     <Compile Include="WebApi\AngularJsonOnlyConfigurationAttribute.cs" />
+    <Compile Include="WebApi\Binders\BlueprintItemBinder.cs" />
     <Compile Include="WebApi\Binders\MemberBinder.cs" />
     <Compile Include="WebApi\EnableDetailedErrorsAttribute.cs" />
     <Compile Include="WebApi\Filters\AngularAntiForgeryHelper.cs" />

src/Umbraco.Web/WebApi/Binders/BlueprintItemBinder.cs

@@ -0,0 +1,28 @@
+using System;
+using Umbraco.Core;
+using Umbraco.Core.Models;
+using Umbraco.Web.Models.ContentEditing;
+
+namespace Umbraco.Web.WebApi.Binders
+{
+    internal class BlueprintItemBinder : ContentItemBinder
+    {
+        public BlueprintItemBinder(ApplicationContext applicationContext)
+            : base(applicationContext)
+        {
+        }
+
+        /// <summary>
+        /// Constructor
+        /// </summary>
+        public BlueprintItemBinder()
+            : this(ApplicationContext.Current)
+        {
+        }
+
+        protected override IContent GetExisting(ContentItemSave model)
+        {
+            return ApplicationContext.Services.ContentService.GetBlueprintById(Convert.ToInt32(model.Id));
+        }        
+    }
+}