How to download student submissions for assignment?

[drscotthawley]

Hi! I've enjoyed playing around with canvasapi and am able to get some basic info from my university's canvas instance.

I apologize for broaching what I imagine is a very common question, but I haven't seen it covered on the Docs page https://canvasapi.readthedocs.io/en/stable/examples.html#assignments
...or elsewhere (see "PS-" at the bottom of this message).

My question is: How do I (programmatically, in Python) download the files that students have submitted for an assignment?

If I execute code such as

canvas = Canvas(API_URL, API_KEY)
course = canvas.get_course(course_id)
assn_id = 1234  
assignment = course.get_assignment(assn_id)
subs = assignment.get_submissions()

.... it gives me a PaginatedList for subs, which I print it out...

for s in subs:
    print(s)

I see a set of strings that read like <assignment_id>-<student_id>.

...But I'm not sure what to do after that! Since the list subs isn't subscriptable, I'm not sure how to investigate what it contains.

Can anyone help? Thanks.

PS- In looking for answers, so far I've only found:

• nothing in these Discussions
• these GUI-based instructions which is not what I want.
• this Canvas LMS Community answer about an API target for listing all assignments, but I don't understand how to make use of the answer given.
• The docs for Submission don't seem to suggest anything for downloading files that students submitted.
• The docs for Assignment have a upload_to_submission target but don't seem to have any corresponding download_from_submssion. :-/

[drscotthawley]

...Ok. Insead I print __dir__() as in:

for s in subs:
    print(s.__dir__())

Then I see a list of attributes that reads

['_requester', 'id', 'body', 'url', 'grade', 'score', 'submitted_at', 'assignment_id', 'user_id', 'user_id_date', 'submission_type', 'workflow_state', 'grade_matches_current_submission', 'graded_at', 'grader_id', 'attempt', 'cached_due_date', 'cached_due_date_date', 'excused', 'late_policy_status', 'points_deducted', 'grading_period_id', 'extra_attempts', 'posted_at', 'redo_request', 'custom_grade_status_id', 'sticker', 'late', 'missing', 'seconds_late', 'entered_grade', 'entered_score', 'preview_url', 'course_id', 'attachments', '__module__', '__init__', '__str__', 'create_submission_peer_review', 'delete_submission_peer_review', 'edit', 'get_submission_peer_reviews', 'mark_read', 'mark_unread', 'upload_comment', '__doc__', '__getattribute__', '__repr__', 'set_attributes', '__dict__', '__weakref__', '__new__', '__hash__', '__setattr__', '__delattr__', '__lt__', '__le__', '__eq__', '__ne__', '__gt__', '__ge__', '__reduce_ex__', '__reduce__', '__getstate__', '__subclasshook__', '__init_subclass__', '__format__', '__sizeof__', '__dir__', '__class__']

....not sure where the attached file is? If I print out attachments it's an empty list, i.e. []. :-/

---

Alternatively, by doing a test submission with "Test Student", I'm able to see that the syntax of the URL that forms for the file download is
https://<university>.instructure.com/courses/<course_id>/assignments/<assignment_id>/submissions/<student_id>?download=1150248&inline=1
Not sure what that "1150248" is for, or how to reliably get that info.
...or how to use that URL with my API_KEY to actually get the file from within Python or Terminal.

[whampt]

Thank you so very much for writing out how to get a list of available attributes for a Canvas object!!
I assume that this is not included in the CanvasAPI documentation as Paginated List is considered Python knowledge not specific to this project.

[drscotthawley]

Oooo! I got it! I could close this thread now, but perhaps I should leave it open in case wiser people want to chime in?

ls = 0
for s in subs:
    print(f"-----\nls={ls}")
    if len(s.attachments) > 0:
        thefile = s.attachments[-1]
        thefile.download(f"a{s.assignment_id}_u{s.user_id}_{thefile}")
    ls+= 1

This will download my students' submitted files to the current directory. Inspecting them locally shows that the files are intact! :-)

Admins, feel free to close if you like.