Add option to make course accessible only through LTI

[PasiSa]

Some courses are intended to be accessible only through LTI (i.e., from MyCourses in Aalto environment) as an LTI tool, and should not be visible in the normal A+ front page, for example to ensure that the grading information flows correctly to the LTI platform. For 1.20 this was fixed as a tweak to the the visible_to_student attribute, but a better way would be to add a dedicated configuration option for this in course attributes, possibly as an additional choice to the enrollment_audience attribute. Such courses should not be visible in the A+ front page, and enrollment should only be possible when accessed from an LTI platform.

The related issue for the fix in 1.20 branch is #1240 .

[markkuriekkinen]

Using CourseInstance.enrollment_audience for this is an interesting idea. It sounds appropriate since in the LTI case, we don't expect enrollments from other sources besides the LTI Platform.

[PasiSa]

In hindsight, why should we have a separate "enrol from SIS" flag, instead of having also that as an enrollment audience option. Maybe there was some reason for that earlier, or was it just an oversight back then?

[markkuriekkinen]

In hindsight, why should we have a separate "enrol from SIS" flag, instead of having also that as an enrollment audience option. Maybe there was some reason for that earlier, or was it just an oversight back then?

I think it was an oversight. However, if we wanted to use both SIS enrollments for internal students and manual enrollments for external (MOOC) students in the same course instance, then we would either use a separate "enrol from SIS" flag or have multiple enrollment audience options for both "only SIS" and "SIS + external manual".