Follow+Notes: Add grant followers management to collaboration library

[TylerHendrickson]

Subtask of [STORY]: Update 'Status' to 'Follow + Note' feature #2960

Blocked by

• Follow+Notes: Create backend library for grants collaboration management #3201

Blocks

• Follow+Notes: Expose grant notes creation in Finder API #3204
• Follow+Notes: Expose ability to follow a grant via Finder API #3206
• Follow+Notes: Expose ability to un-follow a grant via Finder API #3207

Definition of Done

The library at packages/server/src/lib/grantsCollaboration provides new exported functions for adding, removing, and retrieving followers of grants.

Implementation Details

• Create a knex migration that defines a new grant_followers table with the following schema:
  • Columns:
    • id: serial, not null, primary key
    • grant_id: text, not null, foreign key to grants.grant_id
    • user_id: int, not null, foreign key to users.id
    • created_at: timestamp with time zone, not null, default now()
  • Unique index idx_grant_id_user_id on columns (grant_id, user_id)
• Add the following functions to the exported interface of the packages/server/src/lib/grantsCollaboration library:
  • followGrant(knex, grantId, userId) (void)
    • This function should insert a new row into the grant_followers table to record that the identified user is now following the identified grant.
    • The knex argument represents a knex connection object, e.g. as exported by packages/server/src/db/index.js.
    • Unique constraint violations that may occur upon insert (i.e. because the user is already following the grant) should be handled in such a way that any database transaction associated with the provided knex object may proceed. Therefore, this function should begin a new (sub-)transaction before insert, roll back the transaction on unique constraint violation, and commit the transaction following a successful insert.
  • unfollowGrant(knex, grantId, userId) (void)
    • This function should delete the row pertaining to the given user/grant combination from the grant_followers table.
  • Note that while these functions should be exported by the grantsCollaboration library, they should be defined in grantsCollaboration/followers.js and imported/exported in grantsCollaboration/index.js.

[ClaireValdivia]

no front end changes to test, but general regression testing looked good on staging!