[INTF25] - Drop enums from database columns

[mxc-maggiechen]

Notion ticket link

Drop position + department enums

Implementation description

• Add a migration file that changes all position columns from a column of type enum to type string
  • The enums are also making filtering by positions very difficult and jank (related PR: [INTF25] Build filter for fetch review dashboard query #83)
  • And having enums postgres isn't a good idea in general, it makes the database too inflexible to changes
  • The following changes will be made to the database:
    • users table - positions column - type enum_positions_title -> type string (or character varying (255)
    • applicant_records table - positions column - type enum_positions_title -> string (or character varying (255)
    • positions table - title column - type enum_positions_title -> type string (or character varying (255)
    • positions table - department column - type enum_positions_department -> type string (or character varying (255)

• Updated sequelize models to reflect type change
• Updated types to reflect type change

Steps to test

1. Run docker exec recruitment_tools_backend node migrate up to apply the new migration

2. Check the following tables and columns in pgAdmin that they are of the correct type:

   • users table - positions column - type string (or character varying (255)
   • applicant_records table - positions column - type string (or character varying (255)
   • positions table - title column - type string (or character varying (255)
   • positions table - department column - type string (or character varying (255)

3. Run docker exec recruitment_tools_backend node migrate down to undo the changes

4. Check the following tables and columns in pgAdmin that they are restored to the original rtoe:

   • users table - positions column - type enum_positions_title
   • applicant_records table - positions column - type enum_positions_title
   • positions table - title column - type enum_positions_title
   • positions table - department column - type enum_positions_department

What should reviewers focus on?

• The migration script logically make sense and makes the correct updates
• The correct column types changes are made
• Node migrate down restores database to the previous state before the migration

Checklist

• My PR name is descriptive and in imperative tense
• My commit messages are descriptive and in imperative tense. My commits are atomic and trivial commits are squashed or fixup'd into non-trivial commits
• I have run the appropriate linter(s)
• I have requested a review from the PL, as well as other devs who have background knowledge on this PR or who will be building on top of this PR

[mxc-maggiechen]

I had to jump through a lot of hoops to get this migration working... because FK restraints in the database and enum restraints in the database prevented some of the changes. But, the general logic for the migration is as follows:

Drop foreign keys on the columns with the position enums we are trying to remove.
Delete the positions table and recreated it with columns of type string instead of enums.
Convert columns previously of type position enums to string enums.
Re-add the foreign keys to those columns.
At this point, no columns are using the position enums, drop enums.

For the down migration, the same logic applies but it changes the columns from type string back to type position enums.

[ericahan22]

Foreign keys do be a pain in the ass...

[ruiichen]

LGTM 🚢

[ericahan22]

looks good! column types are as described when running (and reverting) the migration