I'm using the migrate module to migrate content from a D6 site.
The D6 site used the image module, with image_gallery.
I can create Gallery nodes [terms in the D6 site].
I can create Media items [image nodes in the D6 site] using MigrateDestinationFile.
What I can't do is wire them together.
It would appear that media items are stored as a reference on the Gallery node.
So I should be able to map that.
I can get a comma separated list of file ids, [or what was their Node ids before import],
so passing that in like this should work
// $media_list looks like this
// $query->addExpression('GROUP_CONCAT(n.nid)', 'media_list');
//$media_list = "234,456,789";
// Pass in the list if images
->arguments(array('source_type' => 'fid'))
but it doesn't.