I got stuck on this just now, I was able to solve the issue using the last example code in this tutorial:
http://www.advancedcustomfields.com/resources/tutorials/querying-relationship-fields/
Aha! Nevermind, I figured it out.
And unlike some people I’ll actually put how I did it! It annoys me so much when people don’t.
Basically you have to select Field Type: Page Link, then you get the option to choose an existing custom post type in a row which appears below. Great feature, cheers.
Thanks a lot for your feedback Elliot. I think I’ll just wait until ACF has support for OPTGROUP in the backend, as the client needs to be able to choose it.
I have one other feature I would like to request or see is possible. When adding a new custom field, with a type of select I would like the choices to be populated from all of the entries in an existing custom post type, instead of manually inputting loads into the Choices textarea. So when creating a new post, the user can select from a dropdown list of all posts in say “Venues” custom post type. I was wondering if you could point me in the right direction of how to do this, and if you think it’s a good suggestion feel free to add it to your todo list.
Cheers!
