Question about LTI and URL homework submission

[kteng]

Hello,

I am writing a LTI provider that intends to perform homework submissions with URLs on behalf of the students.  As a simple test, when logged in as a test student, when I view the assignment in Canvas, which issues the POST request to the LTI launch URL, my LTI provider, using the launch_presentation_return_url value with return_type set to url and url set to an encoded string, will redirect to the submission URL (i.e.,

https://canvas.sfu.ca/courses/38920/external_content/success/external_tool_redirect?return_type=url&url=https%3A%2F%2Fwww.abc.com

).  When I log in as an instructor to verify the homework submission, I find it actually did not go through.  Below are the contents of the LTI POST request.  Any help on how to investigate and proceed would be appreciated

Thanks,

Kenny

context_id	c79c363831cb9371c36891439326c65ff43ad95a
context_label	DM Test
context_title	DM Test
custom_canvas_api_domain	canvas.sfu.ca
custom_canvas_assignment_id	313382
custom_canvas_assignment_points_possible	15
custom_canvas_assignment_title	Assignment 1
custom_canvas_course_id	38920
custom_canvas_enrollment_state	active
custom_canvas_user_id	218980
custom_canvas_user_login_id	lw4661
custom_canvas_workflow_state	available
ext_ims_lis_basic_outcome_url	https://canvas.sfu.ca/api/lti/v1/tools/8212/ext_grade_passback
ext_lti_assignment_id	d195f37a-f8b3-4052-bebf-470f9af3485f
ext_outcome_data_values_accepted	url,text
ext_outcome_result_total_score_accepted	true
ext_outcome_submission_submitted_at_accepted	true
ext_outcomes_tool_placement_url	https://canvas.sfu.ca/api/lti/v1/turnitin/outcomes_placement/8212
ext_roles	urn:lti:instrole:ims/lis/Student,urn:lti:role:ims/lis/Learner,urn:lti:sysrole:ims/lis/User
launch_presentation_document_target	iframe
launch_presentation_locale	en
launch_presentation_return_url	https://canvas.sfu.ca/courses/38920/external_content/success/external_tool_redirect
lis_course_offering_sourcedid	ncc-kteng-42018513
lis_outcome_service_url	https://canvas.sfu.ca/api/lti/v1/tools/8212/grade_passback
lis_person_contact_email_primary	lw4661@sfu.ca
lis_person_name_family	Student1
lis_person_name_full	DMTest Student1
lis_person_name_given	DMTest
lis_person_sourcedid	000035498
lis_result_sourcedid	8212-38920-313382-218980-edab3416f7026aed1f3b83b86e705d6d97de8d94
lti_message_type	basic-lti-launch-request
lti_version	LTI-1p0
oauth_callback	about:blank
oauth_consumer_key	some_consumer_key_10
oauth_nonce	4G4qYMjm7b7nSiu7D150H4npnBemVvChhBolV3A4Hbk
oauth_signature	vXFVbQZUeUeEUrOIJ0anfpg8Gg0=
oauth_signature_method	HMAC-SHA1
oauth_timestamp	1535047840
oauth_version	1.0
resource_link_id	249a8e7faa044f212a586f08e48bdbdc87d706c2
resource_link_title	Assignment 1
roles	Learner
tool_consumer_info_product_family_code	canvas
tool_consumer_info_version	cloud
tool_consumer_instance_contact_email	canvasys@sfu.ca
tool_consumer_instance_guid	b892c4920f8eb0205b7df7e4b0e36bdc5661ace4.canvas.sfu.ca
tool_consumer_instance_name	Simon Fraser University
user_id	981d33f37c651be3dbe43f60ba505767896ff525
user_image	https://canvas.sfu.ca/images/messages/avatar-50.png

[pklove]

I think you are launching your tool as an external assignment rather than launching a normal online asignment and seeing your tool in the submission tabs (File Upload, Text Entry, Website URl, ...).

If your tool is correctly launched for homework submission, you should see the four ext_content_* variables as per Homework Submission Tools - Canvas LMS REST API Documentation. I don't see these listed above.

[pklove]

BTW, I have this working for file submissions, but not for URLs.  For these I an currently getting "The launched tool returned an invalid resource for this assignment".

If you get URLs working I'd like to know what parameters and values you are including.

[107460154315974]

Hi, thanks for all your help in these forums! I have a followup question:

I feel like I'm not fully grasping the differences between a couple of these placements. Is there a placement(s) that will allow a teacher to select an assignment to link to on the tool provider side, and also to allow students to submit their work, using LTI only? So far I'm thinking that there are two not-super-seamless workflows we could use:

1. Assignment_selection placement, letting teachers choose the assignment to link to, and then have to use the REST API for student submissions.
2. Homework_submission placement, letting students choose the work to submit, but then they don't get the LTI launch into the tool. Students could click the link in the course_navigation placement to get to the tool, but I'm still missing the part where the teacher links/selects the assignment from our app.

Am I missing something? Thanks!