Get application parameter inside an Open edX Xblock

Question

Im developing an OpenEdx Xblock.
I need to keep a value amongst all the users and all the xblocks. This value could change eventually, but only by the server admin.
My idea is to create new param in cms.env.json, and retrieve that param in my xblock. I haven't found documentation for this subject.

Answer 1

The proper way to do that would be to store the setting in an XBlock field with the following scope:

BlockScope = TYPE
UserScope = NONE

(See the documentation on xblock scopes: http://edx.readthedocs.io/projects/xblock/en/latest/fields.html#xblock.fields.Scope)

Unfortunately, such a scope does not exist... So you are stuck with using django settings. If you wish to store this setting in the *.env.json files, then this is how you can read the value from inside the xblock:

from django.conf import settings
yourfeature = settings.FEATURES.get('yourfeature', 'defaultvalue')

Don't forget to store this feature value both in lms.env.json and cms.env.json! (provided you need this feature both in the LMS and the CMS)