Using @vercel/postgres

@vercel/postgres can be used as a drop-in replacement for pg. This means that it can be used with Lucia using the pg adapter. Make sure to pass db, which is the equivalent to Pool in pg, since the adapter needs to have access to transactions.

import { lucia } from "lucia";
import { pg } from "@lucia-auth/adapter-postgresql";
import { db } from "@vercel/postgres";

export const auth = lucia({
	adapter: pg(db, {
		// table names
	})
	// ...
});

Errors#

Unfortunately, @vercel/postgres does not export an error class that can be used to check for database errors. Nor are the error types or messages documented, though it’s the same as @neondatabase/serverless. However, the error codes are PostgreSQL error codes, which are well documented.

type VercelPostgresError = {
	code: string;
	detail: string;
	schema?: string;
	table?: string;
	column?: string;
	dataType?: string;
	constraint?: "auth_user_username_key";
};

try {
	// ...
} catch (e) {
	const maybeVercelPostgresError = (
		typeof e === "object" ? e : {}
	) as Partial<VercelPostgresError>;

	// error code for unique constraint violation
	if (maybeVercelError.code === "23505") {
		// ...
	}
}