Depends on what you mean by “this”, I suppose. Most of your basic questions are covered by the starter Rails Guide for ActiveRecord, eg) transactions, validati

Depends on what you mean by “this”, I suppose. Most of your basic questions are covered by the starter Rails Guide for ActiveRecord, eg) transactions, validations, how to add a uniqueness constraint to the DB in a migration https://guides.rubyonrails.org/active_record_basics.html https://guides.rubyonrails.org/active_record_basics.html The ActiveRecord Queries guide also covers some mechanisms for handling row-level write contention https://guides.rubyonrails.org/active_record_querying.html#locking-records-for-update https://guides.rubyonrails.org/active_record_querying.html#l...