Make sure users can only submit as themselves

[oliverjam]

week3-auth-team2/database/model.js

Line 26 in 8ba8bde

const SELLER_ID = `SELECT id FROM devpop_users WHERE devpop_users.name = ($1)`;

Rather than using a user-submitted name (which anyone can guess/fake), you should use the sid from the cookie to look up the seller_id from the sessions table. That way users can only ever submit as themselves, and you can guarantee there will always be a valid user