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Add LTI 1.3 module
Migrated old LTI 1.1 routes to `/lti11/`.
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‎econplayground/lti/README.md

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The lti django app contains all of EconPractice's LTI-related
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code.
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Canvas allows LTI integration in a few different ways. Within a
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course, you can select Settings, and then the Apps tab. From here, you
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can add an LTI app using a number of different methods, i.e.: Manual
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Entry, By URL, Paste XML, By Client ID, or By LTI 2 Registration URL.
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Most of these methods actually refer to the deprecated LTI 1.1
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protocol (keep in mind LTI 2 is also deprecated, and is actually older
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than LTI 1.3). The most reliable method I've found here is to use "By
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Client ID".
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For more context on all this, I have found
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[Canvas's LTI documentation](https://canvas.instructure.com/doc/api/file.tools_intro.html)
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to be pretty straightforward and understandable as an intro to LTI,
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in comparison to the [LTI 1.3 standard](https://www.imsglobal.org/spec/lti/v1p3/)
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itself.
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## EconPractice / Canvas integration (LTI 1.3)
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To integrate EconPractice with Canvas, first we create an LTI
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Registration in EconPractice's admin page:
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* `https://<econpractice hostname>/admin/lti_tool/ltiregistration/`
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1. Click "Add LTI Registration"
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2. Name: Canvas instance hostname, e.g. `canvas.ctl.columbia.edu`
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3. UUID: This is filled in automatically
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4. Issuer: `https://<canvas instance hostname>`
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5. Client ID: Set to 1 for now, this will be updated later
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6. Auth URL: `https://<canvas instance hostname>/api/lti/authorize_redirect`
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7. Access token URL: `https://<canvas instance hostname>/login/oauth2/auth`
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8. Keyset URL: `https://<canvas instance hostname>/api/lti/security/jwks`
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Then, in Canvas, navigate to Admin -> CTL -> Developer Keys.
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1. Click the blue "+ Developer Key" button and select "LTI Key". ("API
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Key" here refers to Canvas's custom API which we don't have special
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integration for, so we definitely want to choose "LTI Key" here.)
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2. Select Method -> Enter URL
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3. Enter the URL: `https://<your econpractice hostname>/lti/<registration uuid>/config.json`
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4. Fill in the Key Name as EconPractice, as well as an admin email for
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Owner Email.
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5. Under Redirect URIs, add: `https://<your econpractice hostname>/lti/launch/`
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6. Click Save
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7. Under "Details", you will see an ID like "10000000000018". This is the "Client ID".
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Go back to the LTI Registration in EconPractice and update the Client ID with this
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value. Without doing this, the LTI launch will raise:
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`OIDCException: Could not find registration details`
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Once the LTI Registration and the Developer Key are in place, you can
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add this LTI App to a course.
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1. Navigate to a course in Canvas, and go to Settings.
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2. Click the Apps tab, and click the "+ App" button to add a new app.
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3. Under Configuration Type, select "By Client ID".
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4. For the Client ID, input the ID of the Developer Key you created, which
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should look something like "10000000000018".
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5. Click Submit.
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The EconPractice LTI app should now be installed in this course. You can
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click on the gear icon, then Placements to see app placements. The
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"Course Navigation" placement should be active, and this is adds a
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"EconPractice" menu item in the course sidebar. Sometimes the Placements
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aren't automatically configured on the first try. If you don't see the
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EconPractice menu item on the left, go back to the Developer Key and see
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how things are configured, and save this again if necessary. This should
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be smoothed over once we migrate to the new "LTI Dynamic Registration",
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which Canvas only recently added support for. See:
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https://github.com/academic-innovation/django-lti/pull/135#issuecomment-2644062255
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Now, there is still one more thing to do: the LTI Deployment must be made
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"active". To do this:
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1. Select the EconPractice menu item in the course. You should receive the
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error message "This deployment is not active". This is an expected error
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message that comes from django-lti.
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2. Navigate to your LTI Registration management admin screen in EconPractice,
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and look under LTI Deployments. You should see one populated now, and
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simply select the "Is Active" checkbox, and Save.
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Now, *finally*, the tool should successfully launch within Canvas.
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## Notes about LTI libraries
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Python support for LTI 1.3 is not in the most cohesive state right now, as
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different people have contributed their efforts at different times and in
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different places. That said, it has been possible to get things working
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building off what open source libraries have been built.
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[pylti1.3](https://github.com/dmitry-viskov/pylti1.3) is a good base to build
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off of. And although it is not actively maintained, it is entirely possible to
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override anything we need to, when necessary.
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A lot of the functionality in pylti1.3 is pretty low-level though, and a lot
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of the LTI transactions and setup can be pre-configured when working with
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Django. Fortunately a lot of this work has been done by the
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[django-lti](https://github.com/academic-innovation/django-lti) library, which
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builds off of pylti1.3. There is some overlap in functionality here, as pylti1.3
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also contains some Django-specific code. But the django-lti library fills in the
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gaps, and is under active development and open to suggestions that we might find
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helpful as we work deeper with LTI 1.3 integration.

‎econplayground/lti/__init__.py

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‎econplayground/lti/admin.py

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# from django.contrib import admin
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# Register your models here.

‎econplayground/lti/apps.py

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from django.apps import AppConfig
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class LtiConfig(AppConfig):
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default_auto_field = 'django.db.models.BigAutoField'
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name = 'lti'

‎econplayground/lti/migrations/__init__.py

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‎econplayground/lti/models.py

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# from django.db import models
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# Create your models here.

‎econplayground/lti/tests.py

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# from django.test import TestCase
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# Create your tests here.

‎econplayground/lti/urls.py

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from django.urls import path
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from econplayground.lti.views import (
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JSONConfigView, LTI1p3LaunchView, MyOIDCLoginInitView
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)
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from lti_tool.views import jwks
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urlpatterns = [
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# django-lti
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path('.well-known/jwks.json', jwks, name='jwks'),
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path('init/<uuid:registration_uuid>/',
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MyOIDCLoginInitView.as_view(), name='oidc_init'),
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path('<uuid:registration_uuid>/config.json',
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JSONConfigView.as_view()),
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path('launch/', LTI1p3LaunchView.as_view(), name='lti-launch'),
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]

‎econplayground/lti/views.py

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from django.conf import settings
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from django.http import JsonResponse
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from django.urls import reverse
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from django.utils.decorators import method_decorator
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from django.views.decorators.clickjacking import xframe_options_exempt
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from django.views.generic.base import View, TemplateView
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from urllib.parse import urljoin
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from lti_tool.views import LtiLaunchBaseView, OIDCLoginInitView
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class JSONConfigView(View):
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"""
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JSON configuration endpoint for LTI 1.3.
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In Canvas LMS, an LTI Developer Key can be created via Manual
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Entry, or by URL. This view provides the JSON necessary for URL
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configuration in Canvas.
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https://canvas.instructure.com/doc/api/file.lti_dev_key_config.html
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"""
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def get(self, request, *args, **kwargs):
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domain = request.get_host()
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title = settings.LTI_TOOL_CONFIGURATION['title']
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icon_url = urljoin(
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settings.STATIC_URL,
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settings.LTI_TOOL_CONFIGURATION['embed_icon_url'])
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target_link_uri = urljoin(
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'https://{}'.format(domain), reverse('lti-launch'))
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uuid = kwargs.get('registration_uuid')
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oidc_init_uri = urljoin(
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'https://{}'.format(domain),
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reverse('oidc_init', kwargs={'registration_uuid': uuid}))
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json_obj = {
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'title': title,
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'description': settings.LTI_TOOL_CONFIGURATION['description'],
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'oidc_initiation_url': oidc_init_uri,
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'target_link_uri': target_link_uri,
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'scopes': [
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'https://purl.imsglobal.org/spec/lti-ags/scope/lineitem',
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'https://purl.imsglobal.org/spec/lti-ags/scope/result.readonly'
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],
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'extensions': [
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{
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'domain': domain,
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'tool_id': 'econpractice',
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'platform': 'canvas.ctl.columbia.edu',
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'privacy_level': 'public',
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'settings': {
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'text': 'Launch ' + title,
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'labels': {
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'en': 'Launch ' + title,
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},
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'icon_url': icon_url,
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'selection_height': 800,
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'selection_width': 800,
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'placements': [
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{
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'text': 'EconPractice',
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'icon_url': icon_url,
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'placement': 'course_navigation',
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'message_type': 'LtiResourceLinkRequest',
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'target_link_uri': target_link_uri,
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'required_permissions': 'manage_calendar',
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'selection_height': 500,
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'selection_width': 500
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}
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]
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}
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}
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],
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'public_jwk_url': urljoin(
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'https://{}'.format(domain), reverse('jwks'))
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}
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return JsonResponse(json_obj)
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@method_decorator(xframe_options_exempt, name='dispatch')
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class MyOIDCLoginInitView(OIDCLoginInitView):
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pass
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@method_decorator(xframe_options_exempt, name='dispatch')
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class LTI1p3LaunchView(LtiLaunchBaseView, TemplateView):
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"""
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https://github.com/academic-innovation/django-lti/blob/main/README.md#handling-an-lti-launch
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"""
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template_name = 'lti_auth/landing_page.html'
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def get_context_data(self, **kwargs):
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domain = self.request.get_host()
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url = settings.LTI_TOOL_CONFIGURATION['landing_url'].format(
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self.request.scheme, domain, kwargs.get('context'))
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return {
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'landing_url': url,
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'title': settings.LTI_TOOL_CONFIGURATION['title']
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}
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def handle_resource_launch(self, request, lti_launch):
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return self.get(request)

‎econplayground/main/tests/test_views.py

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self.submission = SubmissionFactory(graph=self.g, user=self.u)
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def test_get(self):
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request = self.factory.get('/lti/landing/')
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request = self.factory.get('/lti11/landing/')
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request.user = self.u
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view = MyLTILandingPage()
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view.lti = MockLTI()

‎econplayground/settings_shared.py

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LTI_TOOL_CONFIGURATION = {
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'title': 'EconPractice',
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'description': 'Interactive economics graphs',
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'launch_url': 'lti/',
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'launch_url': 'lti11/',
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'embed_url': '',
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'embed_icon_url': 'img/icons/icon-16.png',
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'embed_tool_id': 'econpractice',

‎econplayground/urls.py

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from econplayground.main import views
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from econplayground.assignment import views as assignment_views
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from django_cas_ng import views as cas_views
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from lti_tool.views import jwks, OIDCLoginInitView
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site_media_root = os.path.join(os.path.dirname(__file__), "../media")
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path('smoketest/', include('smoketest.urls')),
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path('uploads/<path>',
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serve, {'document_root': settings.MEDIA_ROOT}),
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path('lti/landing/', views.MyLTILandingPage.as_view()),
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path('lti/', include('lti_provider.urls')),
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# django-lti-provider (LTI 1.1)
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path('lti11/landing/', views.MyLTILandingPage.as_view()),
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path('lti11/', include('lti_provider.urls')),
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# LTI 1.3
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path('lti/', include('econplayground.lti.urls')),
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path('sign_s3/', views.S3SignView.as_view()),
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path('sentry-debug/', trigger_error),
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path('pages/', include('django.contrib.flatpages.urls')),
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# django-lti
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path('.well-known/jwks.json', jwks, name='jwks'),
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path('init/<uuid:registration_uuid>/',
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OIDCLoginInitView.as_view(), name='oidc_init'),
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]
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if settings.DEBUG:

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