Proposal to have sqlc generate string constants for constraints

[andrewmbenton]

I have some code that looks like:

obj, err = queries.SomeQuery() if err != nil { var pgErr *pgconn.PgError if errors.As(err, &pgErr) && pgErr.ConstraintName == "some_unique_key" { // Let user know about constraint violation return	} // Log query failure and return 500 return }

It would be nice if I had string constants for all of my constraint names to compare against, and I think sqlc should be capable of building that for me.

[rhodeon]

I agree this would be a great feature for sqlc to have.
I currently handle this by storing relevant constraints in a contraints.go file under my database directory, like so:

package postgres const ( // UNIQUE KEYS UniqueUsersId = "users_id_key" UniqueGroupId = "group_id_key" UniqueUsersToGroupsUserIdGroupId = "users_to_groups_user_id_group_id_key" // FOREIGN KEYS FKeyUsersToGroupsUserId = "users_to_groups_user_id_fkey" FKeyUsersToGroupsGroupId = "users_to_groups_group_id_fkey" )

Of course, this takes manual effort and isn't foolproof. Having sqlc generate the exhaustive set of available constraints (with commented metadata) if possible would be a massive boon.

If this gets implemented, it would be a good idea to have #835 in mind, as constraints are general to a database and can be centralised in a single file (or package) rather than being repeated per-model.