You can use expressions to present existing data in a fashion that better fits your proposed usage example, manipulating how dates are displayed for instance, or you can use them to build completely new fields from existing database information that are automatically populated, and by their nature, non-editable. You cannot use expressions to populate an existing field such as [album artist]. You
could use an expression to construct the info you desired, then copy that info to [album artist] using the "move/copy field" tool, but, I think, first of all, you need to fully understand how the two fields ([album artist] and [album artist (auto)]) actually work...
[album artist (auto)] is called "
Auto" because it gets filled automatically, and once you understand the automation, you're home and hosed...
So:
It all hinges around the contents of the [artist] field, and the [album artist] field....
First, take all instances where the [album artist] field is empty...
If all the files in any given album have
exactly the same info in the [artist] field, then [album artist (auto)] = [artist]
If any of the files in any given album have any difference in their [artist] fields, then [album artist (auto)] = (Multiple Artists)
and finally...
For any given album, regardless of what is in the [artist] field for any of the tracks, if [album artist] is
not empty, then [album artist (auto)] = [album artist]
Real world examples often help better than words, so, take this Bob Dylan 30th Anniversary Concert cd...
Initially, MC catalogued this (correctly) as "(Multiple Artists)", but I prefer to have it filed along with all the other Bob Dylan albums, and I let MC know this by placing Bob Dylan in the [album artist] field.
So, let's see what you want and how best to achieve it:
Is there an expression I can write that will automatically take what is in AlbumArtist(Auto) and write it into AlbumArtist.
I would also like it to write 'Various Artists' into AlbumArtist if AlbumArtist(Auto) = (Multiple Artists)
Is this possible?
So, following the above logic, what you really want, is to copy the [artist] data over to the [album artist] field, except for where the album is a multi-artist album, in which case, you'd like to fill the [album artist] field with "Various Artists"
Deal with each set of albums at a time, let's do the (Multiple Artists) first.
1. open the tag info window, making sure you can see both the [album artist] and [album artist (auto)] fields.
2. click on "Audio" in the tree.
3. in the search box (top right of the program) type: [album artist (auto)]="Multiple Artists"
4. You now have all your multiple artist albums listed together. Select all files listed and the enter Various Artists into the [album artist] field. [album artist (auto)] for those files will now be "Various Artists"
5. clear the search box, then, in the search box, exclude all those albums by typing: -[album artist (auto)]="Multiple Artists"
6. Select all the files listed, right-click, library tools, move/copy field...
7. set source to [album artist (auto)], set destination to [album artist], set 'action' to 'copy' and click OK
8. Job done (untill you add more albums to your library and so need to keep up the regime)
that do for you?
-marko.