Beginner’s Guide to Ruby on Rails Generators: Start your Rails Application in 3 Steps

Starting a new project is not the easiest task. Especially if you are new to Rails. Wouldn’t it be great if someone could just do some of the codings for us? Then Rails generators are what you need.

With a one-line command in your terminal, Ruby on Rails can create a model, controller, and view files associated with your application! You can even go one step further and add your controller actions and basically get a working app in a couple of minutes by using a Scaffold generator. So let’s start our Rails App by using different generators!

STEP 1 - Before starting using generators, think through your models, attributes, data types… Keep in mind the generated code adheres to RESTful conventions, as well as Model-View-Controller (MVC) patterns.

STEP 2- Start your rails app by simply typing:

rails new your-app-name

Then make sure that you are working in the right folder

cd your-app-name

Now you can check the list of generators simply by typing

rails generate

STEP 3- Go back to step 1 and decide which generators might best serve to create your M-V-C purposes.

1. MODEL GENERATOR

The rails rails generate model NAME command creates your migration and a corresponding table in your database and creates the attributes based on what you pass in after the NAMEof your model.

rails generate model Name column_name:datatype --no-test-framework

A couple of quick notes: Rails is smart enough to understand “g” stands for generate, so you can just type rails g model Name column_name:datatype --no-test-framework

If you are not planning to create tests for your app do not forget to add --no-test-framework

You can add multiple column names rails g model Name column_name:datatype column_name2:datatype2 column?name3:datatype3--no-testframework

DATA TYPES

some of the most common data types you can face are listed below:

:stringfor smaller textual data like a username

:text is for longer texts like comments, reviews and etc.

:integerfor whole numbers

:bigint for arbitrarily large integers

:boolean for true or false values

:datetimefor storing date and time

2. MIGRATION GENERATOR

What if you forgot to add a column to your table? Don’t worry, we have the migration generator to come to our help.

:rails g migration add_NAME_OF_COLUMN_to_table_name name_of_column:datatype --no-test-framework

3. CONTROLLER GENERATOR

More likely than not, we will need a sessions_controller in our projects so it is always handy to use controller generators

rails g controller Controller_Name

So it would look like this to create a sessions controller:

rails g controller sessions --no-test-framework
#AND it would create everything you see below.
create  app/controllers/sessions_controller.rb
invoke  erb
create  app/views/sessions
invoke  helper
create  app/helpers/sessions_helper.rb
invoke  assets
invoke  scss
create  app/assets/stylesheets/sessions.scss

4. RESOURCE GENERATOR

This might be the ideal generator if you don't want to deal with the extra code that comes with scaffolding and is very handy in most cases. The resource generator creates a new Model, corresponding database table, controller, and an empty views folder.

rails g resource ModelName column_name:datatype --no-test-framework

This might be a common example:

rails g resource User username:string email:string password_digest:string --no-test-framework
#which will create 
create    db/migrate/20200919004751_create_users.rb
create    app/models/user.rb
invoke  controller
create    app/controllers/users_controller.rb
invoke    erb
create    app/views/users
invoke    helper
create    app/helpers/users_helper.rb
invoke    assets
invoke    scss
create    /assets/stylesheets/users.scss
invoke    resource_route
route     resources :users

5.SCAFFOLD GENERATOR

Basically, the Scaffold generator creates:

A- The full set of your model.

B- The database migration for that model,

C -The controller with full actions — even the actions you do not need.

D- Views — including the views that you are not going to use. (Needlessly to say, indexing your users is a terrible idea in most cases)

So let’s fırst look into the command line structure.

rails g scaffold ModelName column_name:datatype --no-test-framework

Let’s say if you are working on a Books app this will create

This example creates:

• A Books Controller
• A Book model
• A new resources:books route added to your config/routes.rb file
• A set of test files
• View files under app/views/books

Trivia — Did you know Since Rails 3.0, generators are built on top of Thor API?

6.DESTROYING GENERATED FILES

But what if we accidentally create a file or we use singular instead of plural?

We can just use the format below:

rails destroy generator_type accidentally_created_file

Rails is smart so if you want to destroy the files you created by scaffolding books

rails d scaffold books

Happy coding and please let me know if you have any comments or suggestions!

Sources:

What is Scaffolding in Ruby on Rails?

Creating and Customizing Rails Generators & Templates - Ruby on Rails Guides

https://edgeguides.rubyonrails.org/active_record_migrations.html