I'm trying to do something similar to hidden link
In this form the "Select Campus" and "Select Course" boxes have no options until you select a School. Then they are populated with the relevant Campuses / Courses.
I have 3 post types, Schools, Courses and Reviews.
There are relationships between them as follows:
Schools >> Courses (one-to-many)
Schools >> Reviews (one-to-many)
Courses >> Reviews (one-to-many)
Users can write a review, and when that review post is created the form creates a relationship to both the school and the course.
I have a generic page where they can write these reviews with a post form. The first 2 fields in the form are selects for the School and the course.
As it stands these fields are populated with all the schools and all the courses on the site.
Ideally I'd like it to work so that when they select a school the options on the course select are then limited to only courses in a a relationship with the selected school.
I kind of made this work though it's not as smooth as the example I gave, and it took a lot of work. Maybe it's something Toolset could think about adding as a feature in future.
My solution was as follows:
I used a view showing courses. I use a Toolset filter to filter by school. I used the output of the loop to create another filter showing the courses.
Below this is a form which includes hidden fields for the school ID and course ID.
I then use jquery to update the values of the hidden fields on page load and on filter changes, so when the form is submitted the values of those fields match what's in the view filters.