til/rails/generate-a-model.md

Generate A Model

The rails CLI comes with a variety of generators. Perhaps the mostly common one to use is the model generator.

The model generator will create a migration and a model file for the entity that you name. In the following example Book will result in a app/models/book.rb file as well as a migration file for a books table. These generators know the singular and plural conventions.

At the end of the command is a series of field definitions containing the field name and field type. These are used in the migration file for defining columns on the new table.

❯ bin/rails generate model Book title:string publication_date:date author:string
      invoke  active_record
      create    db/migrate/20240920223447_create_books.rb
      create    app/models/book.rb
      invoke    rspec
      create      spec/models/book_spec.rb

You may also notice that an rspec action was invoked as part of this generator. That is because I have the rspec-rails gem in my project. That gem hooks into the model generator so that a model spec also gets generated. Handy!