Attach file to blog post using widget API

Hi,

I am trying to attach a file to the blog post. below is the code snippet from the functionality implemented in the widget studio:

#set($uploadedFile = $core_v2_uploadedFile.Get($contextId, $fileName))

#set($blogPostResponse = $core_v2_blogPost.Update($core_v2_utility.ParseInt('3'), "%{BlogId = $core_v2_utility.ParseInt('2'), FileData = $uploadedFile.FileData, FileName = $uploadedFile.Name}"))

This gives me the an error as “An error occurred validating a field.  Please go to the previous page and try again. “.

Can anybody please suggest how to pass the  FileData parameter value which is a byte array to the function.

Thanks.