Associations

Booking connects Walker and Dog

A dog walk needs three things to exist: a Walker doing the walking, a Dog going on it, and the booking details themselves. Generate Booking with two references columns — Rails' shorthand for "this points at another table":

bin/rails g model Booking walker:references dog:references starts_at:datetime duration_min:integer price_cents:integer status:string

references does two things at once: it adds a walker_id/dog_id foreign-key column (with a real foreign-key CONSTRAINT in the database, not just a plain integer), and it writes belongs_to :walker / belongs_to :dog into the generated model automatically — you get that part for free.