EPiServer 11：以编程方式转换媒体类型

是否有人尝试在EPiServer中以编程方式转换媒体文件类型？

我们有一个为图像，ImageFile建模的类型，以及一个通过插件添加的类型。我们没有使用插件添加的类型，但发现上传的图像会不时被创建为错误的类型。我希望弄清楚如何进行转换，以便我可以运行计划的作业来批量转换所有内容，然后删除插件。

到目前为止，我可以通过编程方式将A复制为B类型，然后删除A。我真正想做的是将A转换为B以实现无缝过渡。

我尝试的第一件事是将映像克隆为正确的类型，但结果为null

var media = _contentRepository.Service.GetDescendents(SiteDefinition.Current.GlobalAssetsRoot)
                .Where(i => _contentRepository.Service.Get<IContent>(i) is MediaData);
var imageFileTypeId = new ImageFile().ContentTypeID;
foreach (var img in media)
{
    if (img.Get<IContent>() is GcEpiImageFile)
    {
         count++ // for summary
         var item = _contentLoader.Service.Get<GcEpiImageFile>(img.Get<IContent>().ContentLink);
         var cloneItem = item.CreateWritableClone() as ImageFile;
         if (cloneItem == null) 
         {
             var msg = $"{item.Name}: {item.ContentLink.ID} came up null";
             OnStatusChanged(msg);
             summaryMessage.AppendLine(msg);
             continue;
         }
         cloneItem.ContentTypeID = imageFileTypeId;
         _contentRepository.Service.Save(cloneItem, SaveAction.Publish, AccessLevel.NoAccess);

    }

我尝试的下一步是将其克隆为似乎创建对象的基类ImageData，但在保存时会抛出未设置为对象异常实例的Object引用。

var media = _contentRepository.Service.GetDescendents(SiteDefinition.Current.GlobalAssetsRoot)
                .Where(i => _contentRepository.Service.Get<IContent>(i) is MediaData);
var imageFileTypeId = new ImageFile().ContentTypeID;
foreach (var img in media)
{
    if (img.Get<IContent>() is GcEpiImageFile)
    {
         count++ // for summary
         var item = _contentLoader.Service.Get<GcEpiImageFile>(img.Get<IContent>().ContentLink);
         var cloneItem = item.CreateWritableClone() as ImageData;
         if (cloneItem == null) 
         {
             var msg = $"{item.Name}: {item.ContentLink.ID} came up null";
             OnStatusChanged(msg);
             summaryMessage.AppendLine(msg);
             continue;
         }
         try
         { 
             cloneItem.ContentTypeID = imageFileTypeId;
         }
         catch (Exception ex)
         {
             summaryMessage.AppendLine($"exception triggered by id assignment {ex.Message}<br />{ex.InnerException}");
         }
         try
         { 
             _contentRepository.Service.Save(cloneItem, SaveAction.Publish, AccessLevel.NoAccess);
         }
         catch (Exception ex)
         {
             summaryMessage.AppendLine(
                            $"exception triggered by save {ex.Message}<br />{ex.InnerException}");
         }
    }

这是我的堆栈跟踪：

Object reference not set to an instance of an object.
at EPiServer.Validation.Internal.RoutingSegmentValidator.Validate(IContent instance) at

EPiServer.Validation.Internal.ContextValidatorWrapper`2.Validate(Object instance, Object context) 

at EPiServer.Validation.Internal.ValidationService.ValidateRecursively(Object instance, Object context, HashSet`1 visitedInstances) 

at EPiServer.Validation.Internal.ValidationService.Validate[T](Object instance, T context) 

at EPiServer.Core.ContentProvider.Validate(IContent content, ContentSaveValidationContext saveValidationContext) 

at EPiServer.Core.Internal.DefaultContentRepository.Save(IContent content, SaveAction action, AccessLevel access) at Web.Business.ScheduledJobs.ImageConversion.Execute()

任何想法，帮助，指导将不胜感激