The Schema

Six tables, in plain words

db/schema.rb is auto-generated — you never hand-edit it, migrations produce it — but it's the fastest way to see the whole shape of the app at once. Six tables (a seventh, payments, shows up in module 12):

• users — an account: name, email, password_digest (module 10 explains that column).
• walkers — a dog walker for hire: name, city, price_per_30_min_cents, rating. Nothing links a walker to a user yet — walkers aren't users in this app, just listings.
• dogs — belongs to a user: name, breed, size.
• bookings — the hub. It references user, walker, AND dog all at once: a user books a specific dog with a specific walker.
• walk_sessions — one per booking (has_one), tracks started_at/ended_at for the walk actually happening.
• location_pings — many per walk_session, a GPS fix at a moment in time (lat, lng, recorded_at).

In one sentence: users → dogs, and users + walkers + dogs → bookings → walk_sessions → location_pings. Everything downstream of a booking exists because that booking exists.