I have three channels: Books, Screenplays, and Reviews. The Reviews channel includes a relationships field, where the user can assign the review to a particular book or screenplay. Thus the relationships field draws its available choices from two channels, but the relationship itself is one-to-one (ie. Allow Multiple Relations is OFF).
As I understand it, this means that I have one parent channel (Reviews) and two child channels (Books and Screenplays).
I have no problem displaying the reviews for a specific book on the book's own page (/books/view/the-book-i-wrote); I do that by accessing the {parents} tag from inside a {exp:channel:entries channel=books} tag. However, what I also want to do is have a list of general book reviews on the book index page (/books/index.php) -- NOTE: book reviews only, excluding any screenplay reviews. So I want to limit the results derived from the reviews channel to ONLY those reviews that have been assigned a relationship to an entry residing in a specific child channel. I cannot work out how to do this.
I realised that assigning a channel parameter to the {parents} tag is not the way -- it is intended to differentiate between multiple parent channels, not limit the results derived from a particular parent.
Can anyone help me untangle this? Thanks.