Backend: Course assignment models and sync considerations

[rtibbles]

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Overview

Create models for course assignments to support coaches assigning courses to learners and learner groups.

Tentative Model Structure

Based on existing patterns from Lesson and LessonAssignment:

from morango.models import UUIDField

class CourseAssignment(AbstractFacilityDataModel):
    """
    Links a course ContentNode to Collections (Classroom or LearnerGroup)
    """
    
    # UUID reference to the course ContentNode (not FK due to sync constraints)
    course = UUIDField()
    
    # The Collection (Classroom or LearnerGroup) assigned to
    collection = models.ForeignKey(Collection, ...)
    
    # Who made the assignment
    assigned_by = models.ForeignKey(FacilityUser, ...)
    
    # Whether the assignment is active/visible
    is_active = models.BooleanField(default=False)
    
    # Permissions (coach/admin can create/read/update/delete)
    permissions = RoleBasedPermissions(
        target_field="collection",
        can_be_created_by=(role_kinds.ADMIN, role_kinds.COACH),
        can_be_read_by=(role_kinds.ADMIN, role_kinds.COACH),
        can_be_updated_by=(role_kinds.ADMIN, role_kinds.COACH),
        can_be_deleted_by=(role_kinds.ADMIN, role_kinds.COACH),
    )
    
    # Morango fields
    morango_model_name = "courseassignment"

Why UUIDField instead of ForeignKey: ContentNodes are not synced with facility data, so a foreign key would fail referential integrity checks during sync. Using UUIDField allows the assignment to exist even if the course content isn't currently available on a device.

Questions to Answer

Primary Question: Sync Scope

Should course assignments sync with full facility metadata, or use collection-based selective syncing?

• Full facility sync: All course assignments for a facility sync together (simpler, current default)
• Collection-based sync: Only sync assignments for collections a user is a member of (requires Morango updates)

Collection-based syncing would require:

• Updates to Morango to make synced data dependent on user's collection membership
• More complex partition/filter logic
• Better performance and privacy for large multi-classroom facilities

Secondary Questions

1. Redundant metadata storage: Should we store course title, channel_id, content_id for offline/sync scenarios where the course ContentNode isn't available?

2. Missing course handling: What should the UI show when a CourseAssignment references a course that isn't available on the device?

3. Assignment limits: Should there be constraints on number of active course assignments per classroom?

4. Morango partitioning: How should calculate_partition() work - by dataset_id or collection_id?

References

• Existing models: kolibri/core/lessons/models.py
• Assignment patterns: kolibri/core/content/utils/assignment.py
• Morango UUIDField: morango.models.fields.UUIDField