it is quite often when we need to have an autocomplete element that searches courses that
have completion enabled. This commit adds an option for the 'course' form element, and also
changes two places where we search for courses with completion. This should fix MDL-58989
This is a squashed commit containing a number of changes:
This is an ajax driven course selector that has searching etc. It can select single, or multiple courses.
Make course selector accept a list of courses to exclude
courseselector - lookup coursename on setValue
Use the get_course_display_name_in_list function to generate the course names
Add a throttle to auto-complete to reduce spamming the server
Do a single query to fetch all the courses in the mform element when validation fails
Fix core course search function to return results when there are less than 2 chars in the query.
Handle setData with an empty array in new course selector
