<%= @message %>
``` Fire up your server using `rails server`. ```bash $ rails server => Booting Puma... ``` The URL will be [http://localhost:3000/greetings/hello](http://localhost:3000/greetings/hello). INFO: With a normal, plain-old Rails application, your URLs will generally follow the pattern of http://(host)/(controller)/(action), and a URL like http://(host)/(controller) will hit the **index** action of that controller. Rails comes with a generator for data models too. ```bash $ rails generate model Usage: rails generate model NAME [field[:type][:index] field[:type][:index]] [options] ... Active Record options: [--migration] # Indicates when to generate migration # Default: true ... Description: Create rails files for model generator. ``` NOTE: For a list of available field types for the `type` parameter, refer to the [API documentation](https://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/SchemaStatements.html#method-i-add_column) for the add_column method for the `SchemaStatements` module. The `index` parameter generates a corresponding index for the column. But instead of generating a model directly (which we'll be doing later), let's set up a scaffold. A **scaffold** in Rails is a full set of model, database migration for that model, controller to manipulate it, views to view and manipulate the data, and a test suite for each of the above. We will set up a simple resource called "HighScore" that will keep track of our highest score on video games we play. ```bash $ rails generate scaffold HighScore game:string score:integer invoke active_record create db/migrate/20130717151933_create_high_scores.rb create app/models/high_score.rb invoke test_unit create test/models/high_score_test.rb create test/fixtures/high_scores.yml invoke resource_route route resources :high_scores invoke scaffold_controller create app/controllers/high_scores_controller.rb invoke erb create app/views/high_scores create app/views/high_scores/index.html.erb create app/views/high_scores/edit.html.erb create app/views/high_scores/show.html.erb create app/views/high_scores/new.html.erb create app/views/high_scores/_form.html.erb invoke test_unit create test/controllers/high_scores_controller_test.rb invoke helper create app/helpers/high_scores_helper.rb invoke jbuilder create app/views/high_scores/index.json.jbuilder create app/views/high_scores/show.json.jbuilder invoke test_unit create test/system/high_scores_test.rb invoke assets invoke coffee create app/assets/javascripts/high_scores.coffee invoke scss create app/assets/stylesheets/high_scores.scss invoke scss identical app/assets/stylesheets/scaffolds.scss ``` The generator checks that there exist the directories for models, controllers, helpers, layouts, functional and unit tests, stylesheets, creates the views, controller, model and database migration for HighScore (creating the `high_scores` table and fields), takes care of the route for the **resource**, and new tests for everything. The migration requires that we **migrate**, that is, run some Ruby code (living in that `20130717151933_create_high_scores.rb`) to modify the schema of our database. Which database? The SQLite3 database that Rails will create for you when we run the `rails db:migrate` command. We'll talk more about that command below. ```bash $ rails db:migrate == CreateHighScores: migrating =============================================== -- create_table(:high_scores) -> 0.0017s == CreateHighScores: migrated (0.0019s) ====================================== ``` INFO: Let's talk about unit tests. Unit tests are code that tests and makes assertions about code. In unit testing, we take a little part of code, say a method of a model, and test its inputs and outputs. Unit tests are your friend. The sooner you make peace with the fact that your quality of life will drastically increase when you unit test your code, the better. Seriously. Please visit [the testing guide](https://guides.rubyonrails.org/testing.html) for an in-depth look at unit testing. Let's see the interface Rails created for us. ```bash $ rails server ``` Go to your browser and open [http://localhost:3000/high_scores](http://localhost:3000/high_scores), now we can create new high scores (55,160 on Space Invaders!) ### `rails console` The `console` command lets you interact with your Rails application from the command line. On the underside, `rails console` uses IRB, so if you've ever used it, you'll be right at home. This is useful for testing out quick ideas with code and changing data server-side without touching the website. INFO: You can also use the alias "c" to invoke the console: `rails c`. You can specify the environment in which the `console` command should operate. ```bash $ rails console -e staging ``` If you wish to test out some code without changing any data, you can do that by invoking `rails console --sandbox`. ```bash $ rails console --sandbox Loading development environment in sandbox (Rails 5.1.0) Any modifications you make will be rolled back on exit irb(main):001:0> ``` #### The app and helper objects Inside the `rails console` you have access to the `app` and `helper` instances. With the `app` method you can access URL and path helpers, as well as do requests. ```bash >> app.root_path => "/" >> app.get _ Started GET "/" for 127.0.0.1 at 2014-06-19 10:41:57 -0300 ... ``` With the `helper` method it is possible to access Rails and your application's helpers. ```bash >> helper.time_ago_in_words 30.days.ago => "about 1 month" >> helper.my_custom_helper => "my custom helper" ``` ### `rails dbconsole` `rails dbconsole` figures out which database you're using and drops you into whichever command line interface you would use with it (and figures out the command line parameters to give to it, too!). It supports MySQL (including MariaDB), PostgreSQL, and SQLite3. INFO: You can also use the alias "db" to invoke the dbconsole: `rails db`. ### `rails runner` `runner` runs Ruby code in the context of Rails non-interactively. For instance: ```bash $ rails runner "Model.long_running_method" ``` INFO: You can also use the alias "r" to invoke the runner: `rails r`. You can specify the environment in which the `runner` command should operate using the `-e` switch. ```bash $ rails runner -e staging "Model.long_running_method" ``` You can even execute ruby code written in a file with runner. ```bash $ rails runner lib/code_to_be_run.rb ``` ### `rails destroy` Think of `destroy` as the opposite of `generate`. It'll figure out what generate did, and undo it. INFO: You can also use the alias "d" to invoke the destroy command: `rails d`. ```bash $ rails generate model Oops invoke active_record create db/migrate/20120528062523_create_oops.rb create app/models/oops.rb invoke test_unit create test/models/oops_test.rb create test/fixtures/oops.yml ``` ```bash $ rails destroy model Oops invoke active_record remove db/migrate/20120528062523_create_oops.rb remove app/models/oops.rb invoke test_unit remove test/models/oops_test.rb remove test/fixtures/oops.yml ``` ### `rails about` `rails about` gives information about version numbers for Ruby, RubyGems, Rails, the Rails subcomponents, your application's folder, the current Rails environment name, your app's database adapter, and schema version. It is useful when you need to ask for help, check if a security patch might affect you, or when you need some stats for an existing Rails installation. ```bash $ rails about About your application's environment Rails version 6.0.0 Ruby version 2.5.0 (x86_64-linux) RubyGems version 2.7.3 Rack version 2.0.4 JavaScript Runtime Node.js (V8) Middleware: Rack::Sendfile, ActionDispatch::Static, ActionDispatch::Executor, ActiveSupport::Cache::Strategy::LocalCache::Middleware, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, ActionDispatch::RemoteIp, Sprockets::Rails::QuietAssets, Rails::Rack::Logger, ActionDispatch::ShowExceptions, WebConsole::Middleware, ActionDispatch::DebugExceptions, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::Migration::CheckPending, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, Rack::Head, Rack::ConditionalGet, Rack::ETag Application root /home/foobar/commandsapp Environment development Database adapter sqlite3 Database schema version 20180205173523 ``` ### `rails assets:` You can precompile the assets in `app/assets` using `rails assets:precompile`, and remove older compiled assets using `rails assets:clean`. The `assets:clean` command allows for rolling deploys that may still be linking to an old asset while the new assets are being built. If you want to clear `public/assets` completely, you can use `rails assets:clobber`. ### `rails db:` The most common commands of the `db:` rails namespace are `migrate` and `create`, and it will pay off to try out all of the migration rails commands (`up`, `down`, `redo`, `reset`). `rails db:version` is useful when troubleshooting, telling you the current version of the database. More information about migrations can be found in the [Migrations](active_record_migrations.html) guide. ### `rails notes` `rails notes` searches through your code for comments beginning with a specific keyword. You can refer to `rails notes --help` for information about usage. By default, it will search in `app`, `config`, `db`, `lib`, and `test` directories for FIXME, OPTIMIZE, and TODO annotations in files with extension `.builder`, `.rb`, `.rake`, `.yml`, `.yaml`, `.ruby`, `.css`, `.js`, and `.erb`. ```bash $ rails notes app/controllers/admin/users_controller.rb: * [ 20] [TODO] any other way to do this? * [132] [FIXME] high priority for next deploy lib/school.rb: * [ 13] [OPTIMIZE] refactor this code to make it faster * [ 17] [FIXME] ``` #### Annotations You can pass specific annotations by using the `--annotations` argument. By default, it will search for FIXME, OPTIMIZE, and TODO. Note that annotations are case sensitive. ```bash $ rails notes --annotations FIXME RELEASE app/controllers/admin/users_controller.rb: * [101] [RELEASE] We need to look at this before next release * [132] [FIXME] high priority for next deploy lib/school.rb: * [ 17] [FIXME] ``` #### Tags You can add more default tags to search for by using `config.annotations.register_tags`. It receives a list of tags. ```ruby config.annotations.register_tags("DEPRECATEME", "TESTME") ``` ```bash $ rails notes app/controllers/admin/users_controller.rb: * [ 20] [TODO] do A/B testing on this * [ 42] [TESTME] this needs more functional tests * [132] [DEPRECATEME] ensure this method is deprecated in next release ``` #### Directories You can add more default directories to search from by using `config.annotations.register_directories`. It receives a list of directory names. ```ruby config.annotations.register_directories("spec", "vendor") ``` ```bash $ rails notes app/controllers/admin/users_controller.rb: * [ 20] [TODO] any other way to do this? * [132] [FIXME] high priority for next deploy lib/school.rb: * [ 13] [OPTIMIZE] Refactor this code to make it faster * [ 17] [FIXME] spec/models/user_spec.rb: * [122] [TODO] Verify the user that has a subscription works vendor/tools.rb: * [ 56] [TODO] Get rid of this dependency ``` #### Extensions You can add more default file extensions to search from by using `config.annotations.register_extensions`. It receives a list of extensions with its corresponding regex to match it up. ```ruby config.annotations.register_extensions("scss", "sass") { |annotation| /\/\/\s*(#{annotation}):?\s*(.*)$/ } ``` ```bash $ rails notes app/controllers/admin/users_controller.rb: * [ 20] [TODO] any other way to do this? * [132] [FIXME] high priority for next deploy app/assets/stylesheets/application.css.sass: * [ 34] [TODO] Use pseudo element for this class app/assets/stylesheets/application.css.scss: * [ 1] [TODO] Split into multiple components lib/school.rb: * [ 13] [OPTIMIZE] Refactor this code to make it faster * [ 17] [FIXME] spec/models/user_spec.rb: * [122] [TODO] Verify the user that has a subscription works vendor/tools.rb: * [ 56] [TODO] Get rid of this dependency ``` ### `rails routes` `rails routes` will list all of your defined routes, which is useful for tracking down routing problems in your app, or giving you a good overview of the URLs in an app you're trying to get familiar with. ### `rails test` INFO: A good description of unit testing in Rails is given in [A Guide to Testing Rails Applications](testing.html) Rails comes with a test framework called minitest. Rails owes its stability to the use of tests. The commands available in the `test:` namespace helps in running the different tests you will hopefully write. ### `rails tmp:` The `Rails.root/tmp` directory is, like the *nix /tmp directory, the holding place for temporary files like process id files and cached actions. The `tmp:` namespaced commands will help you clear and create the `Rails.root/tmp` directory: * `rails tmp:cache:clear` clears `tmp/cache`. * `rails tmp:sockets:clear` clears `tmp/sockets`. * `rails tmp:screenshots:clear` clears `tmp/screenshots`. * `rails tmp:clear` clears all cache, sockets, and screenshot files. * `rails tmp:create` creates tmp directories for cache, sockets, and pids. ### Miscellaneous * `rails stats` is great for looking at statistics on your code, displaying things like KLOCs (thousands of lines of code) and your code to test ratio. * `rails secret` will give you a pseudo-random key to use for your session secret. * `rails time:zones:all` lists all the timezones Rails knows about. ### Custom Rake Tasks Custom rake tasks have a `.rake` extension and are placed in `Rails.root/lib/tasks`. You can create these custom rake tasks with the `rails generate task` command. ```ruby desc "I am short, but comprehensive description for my cool task" task task_name: [:prerequisite_task, :another_task_we_depend_on] do # All your magic here # Any valid Ruby code is allowed end ``` To pass arguments to your custom rake task: ```ruby task :task_name, [:arg_1] => [:prerequisite_1, :prerequisite_2] do |task, args| argument_1 = args.arg_1 end ``` You can group tasks by placing them in namespaces: ```ruby namespace :db do desc "This task does nothing" task :nothing do # Seriously, nothing end end ``` Invocation of the tasks will look like: ```bash $ rails task_name $ rails "task_name[value 1]" # entire argument string should be quoted $ rails db:nothing ``` NOTE: If you need to interact with your application models, perform database queries, and so on, your task should depend on the `environment` task, which will load your application code. The Rails Advanced Command Line ------------------------------- More advanced use of the command line is focused around finding useful (even surprising at times) options in the utilities, and fitting those to your needs and specific work flow. Listed here are some tricks up Rails' sleeve. ### Rails with Databases and SCM When creating a new Rails application, you have the option to specify what kind of database and what kind of source code management system your application is going to use. This will save you a few minutes, and certainly many keystrokes. Let's see what a `--git` option and a `--database=postgresql` option will do for us: ```bash $ mkdir gitapp $ cd gitapp $ git init Initialized empty Git repository in .git/ $ rails new . --git --database=postgresql exists create app/controllers create app/helpers ... ... create tmp/cache create tmp/pids create Rakefile add 'Rakefile' create README.md add 'README.md' create app/controllers/application_controller.rb add 'app/controllers/application_controller.rb' create app/helpers/application_helper.rb ... create log/test.log add 'log/test.log' ``` We had to create the **gitapp** directory and initialize an empty git repository before Rails would add files it created to our repository. Let's see what it put in our database configuration: ```bash $ cat config/database.yml # PostgreSQL. Versions 9.1 and up are supported. # # Install the pg driver: # gem install pg # On macOS with Homebrew: # gem install pg -- --with-pg-config=/usr/local/bin/pg_config # On macOS with MacPorts: # gem install pg -- --with-pg-config=/opt/local/lib/postgresql84/bin/pg_config # On Windows: # gem install pg # Choose the win32 build. # Install PostgreSQL and put its /bin directory on your path. # # Configure Using Gemfile # gem 'pg' # default: &default adapter: postgresql encoding: unicode # For details on connection pooling, see Rails configuration guide # https://guides.rubyonrails.org/configuring.html#database-pooling pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %> development: <<: *default database: gitapp_development ... ... ``` It also generated some lines in our `database.yml` configuration corresponding to our choice of PostgreSQL for database. NOTE. The only catch with using the SCM options is that you have to make your application's directory first, then initialize your SCM, then you can run the `rails new` command to generate the basis of your app.