What's the best way for an LTI app to get a list of teachers?

[austinmbrown]

I've been working on an LTI app for Canvas that aggregates information about instructors within the account. There doesn't seem to be a great way to do this and I'm wondering if I'm missing something. Currently, I have an ugly and super-slow multi-step process via the API where I get all courses, then get the teacher enrollments from each course, then get the corresponding users. For big accounts, this does not work well.

I just found some information in the LTI spec about a Membership Service (Learning Tools Interoperability: Implementing Membership service | IMS Global Learning Consortium ) It looks like the spec expects a consumer (like Canvas) to provide a link at which the tool can request users within that context (and allows for filtering by role). From what I can tell Canvas doesn't do this, though? The parameter listed in the spec doesn't appear to be included in Canvas's launch request. Am I missing it? Is there a way to activate it or request it somehow in the way you configure the tool maybe?

[mwhite]

I have fought many a battles trying to get specific info from Canvas API and am all too familiar with the multi-step request process. I am going to think about this and see if I can put together any scheme for you.

Do you have any server side caching abilities? This was a strategy I used at one point when I needed to get student submissions across a ton of courses but only for a specific assignment in each course.

[austinmbrown]

Yes I can cache server side, that was really the only solution. The question still remains about efficiency, though. I was hoping there was a way to work around the API and get the data during the LTI handoff, but that doesn't seem to be possible. Internally, Canvas has a sub-class for TeacherEnrollments so finding teachers shouldn't be that hard, but they're not exposed to the API in a straightforward way.

After some further investigation, I'm thinking one option is the

/api/v1/accounts/:account_id/courses

endpoint. (Accounts - Canvas LMS REST API Documentation)  It has options to filter courses and to include the teachers in the response. This cuts out the enrollments step from my previous process. Unfortunately the Pandarus gem doesn't handle this endpoint properly, so I'm working on querying it with HTTParty myself ¯\_(ツ)_/¯