Admin class management (backend)

[jansm04]

Updated and added backend functionality for the admin class management module. Merged #42 midway through to make sure new code in the model classes was consistent with the mysql2 changes.

Class Module

• created a PUT endpoint to allow admins to update classes
• created a DELETE endpoint to delete classes by ID
• added subcategory to addClass() parameters as it was missing

Schedule Module

• created a DELETE endpoint to delete all schedules included in a given list of schedule IDs
• fixed a bug in setSchedulesByClassId() where added list of schedules was creating an invalid SQL query

Shift Module

• added shift_id to shifts table in DB to replace (fk_volunteer_id, fk_schedule_id, shift_date) as PK
• updated shift_coverage_request in DB to reference shifts using shift_id
• updated the GetShiftsByVolunteerIdAndMonth procedure in procedures.sql to use shift_id for joins involving shifts table
• implemented POST, PUT and DELETE endpoints in the shifts module

Don't think any existing functions in the shifts model needed to be updated as a result of the PK change btw.

Tested all the endpoints too and should be good to go

[jjessieshang]

Adding shift_id to the shifts table will be a big improvement to allow for empty shifts. Thank you Jan for making the adjustment everywhere and also in the ERM diagram.

• Endpoints looks good to me, just need to resolve the merge conflicts
• Next step for your add classes module will be to build the frontend and connect with these endpoints once design is ready :)

[theosiemensrhodes]

LGTM

good luck on the monster merge