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<h2>The Rails Command Line</h2><p>After reading this guide, you will know:</p>
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<li>How to create a Rails application.</li>
<li>How to generate models, controllers, database migrations, and unit tests.</li>
<li>How to start a development server.</li>
<li>How to experiment with objects through an interactive shell.</li>
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<li><a href="#rails-new"><code>rails new</code></a></li>
<li><a href="#rails-server"><code>rails server</code></a></li>
<li><a href="#rails-generate"><code>rails generate</code></a></li>
<li><a href="#rails-console"><code>rails console</code></a></li>
<li><a href="#rails-dbconsole"><code>rails dbconsole</code></a></li>
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<li><a href="#rails-about"><code>rails about</code></a></li>
<li><a href="#rails-assets"><code>rails assets:</code></a></li>
<li><a href="#rails-db"><code>rails db:</code></a></li>
<li><a href="#rails-notes"><code>rails notes</code></a></li>
<li><a href="#rails-routes"><code>rails routes</code></a></li>
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<div class="note"><p>This tutorial assumes you have basic Rails knowledge from reading the <a href="getting_started.html">Getting Started with Rails Guide</a>.</p></div><h3 id="command-line-basics"><a class="anchorlink" href="#command-line-basics">1 Command Line Basics</a></h3><p>There are a few commands that are absolutely critical to your everyday usage of Rails. In the order of how much you'll probably use them are:</p>
<ul>
<li><code>rails console</code></li>
<li><code>rails server</code></li>
<li><code>rails test</code></li>
<li><code>rails generate</code></li>
<li><code>rails db:migrate</code></li>
<li><code>rails db:create</code></li>
<li><code>rails routes</code></li>
<li><code>rails dbconsole</code></li>
<li><code>rails new app_name</code></li>
</ul>
<p>You can get a list of rails commands available to you, which will often depend on your current directory, by typing <code>rails --help</code>. Each command has a description, and should help you find the thing you need.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails --help
Usage: rails COMMAND [ARGS]
The most common rails commands are:
generate Generate new code (short-cut alias: "g")
console Start the Rails console (short-cut alias: "c")
server Start the Rails server (short-cut alias: "s")
...
All commands can be run with -h (or --help) for more information.
In addition to those commands, there are:
about List versions of all Rails ...
assets:clean[keep] Remove old compiled assets
assets:clobber Remove compiled assets
assets:environment Load asset compile environment
assets:precompile Compile all the assets ...
...
db:fixtures:load Loads fixtures into the ...
db:migrate Migrate the database ...
db:migrate:status Display status of migrations
db:rollback Rolls the schema back to ...
db:schema:cache:clear Clears a db/schema_cache.yml file
db:schema:cache:dump Creates a db/schema_cache.yml file
db:schema:dump Creates a db/schema.rb file ...
db:schema:load Loads a schema.rb file ...
db:seed Loads the seed data ...
db:structure:dump Dumps the database structure ...
db:structure:load Recreates the databases ...
db:version Retrieves the current schema ...
...
restart Restart app by touching ...
tmp:create Creates tmp directories ...
</pre>
</div>
<p>Let's create a simple Rails application to step through each of these commands in context.</p><h4 id="rails-new"><a class="anchorlink" href="#rails-new">1.1 <code>rails new</code></a></h4><p>The first thing we'll want to do is create a new Rails application by running the <code>rails new</code> command after installing Rails.</p><div class="info"><p>You can install the rails gem by typing <code>gem install rails</code>, if you don't have it already.</p></div><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails new commandsapp
create
create README.md
create Rakefile
create config.ru
create .gitignore
create Gemfile
create app
...
create tmp/cache
...
run bundle install
</pre>
</div>
<p>Rails will set you up with what seems like a huge amount of stuff for such a tiny command! You've got the entire Rails directory structure now with all the code you need to run our simple application right out of the box.</p><h4 id="rails-server"><a class="anchorlink" href="#rails-server">1.2 <code>rails server</code></a></h4><p>The <code>rails server</code> command launches a web server named Puma which comes bundled with Rails. You'll use this any time you want to access your application through a web browser.</p><p>With no further work, <code>rails server</code> will run our new shiny Rails app:</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ cd commandsapp
$ rails server
=> Booting Puma
=> Rails 5.1.0 application starting in development on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.0.2 (ruby 2.3.0-p0), codename: Plethora of Penguin Pinatas
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://localhost:3000
Use Ctrl-C to stop
</pre>
</div>
<p>With just three commands we whipped up a Rails server listening on port 3000. Go to your browser and open <a href="http://localhost:3000">http://localhost:3000</a>, you will see a basic Rails app running.</p><div class="info"><p>You can also use the alias "s" to start the server: <code>rails s</code>.</p></div><p>The server can be run on a different port using the <code>-p</code> option. The default development environment can be changed using <code>-e</code>.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails server -e production -p 4000
</pre>
</div>
<p>The <code>-b</code> option binds Rails to the specified IP, by default it is localhost. You can run a server as a daemon by passing a <code>-d</code> option.</p><h4 id="rails-generate"><a class="anchorlink" href="#rails-generate">1.3 <code>rails generate</code></a></h4><p>The <code>rails generate</code> command uses templates to create a whole lot of things. Running <code>rails generate</code> by itself gives a list of available generators:</p><div class="info"><p>You can also use the alias "g" to invoke the generator command: <code>rails g</code>.</p></div><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails generate
Usage: rails generate GENERATOR [args] [options]
...
...
Please choose a generator below.
Rails:
assets
channel
controller
generator
...
...
</pre>
</div>
<div class="note"><p>You can install more generators through generator gems, portions of plugins you'll undoubtedly install, and you can even create your own!</p></div><p>Using generators will save you a large amount of time by writing <strong>boilerplate code</strong>, code that is necessary for the app to work.</p><p>Let's make our own controller with the controller generator. But what command should we use? Let's ask the generator:</p><div class="info"><p>All Rails console utilities have help text. As with most *nix utilities, you can try adding <code>--help</code> or <code>-h</code> to the end, for example <code>rails server --help</code>.</p></div><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails generate controller
Usage: rails generate controller NAME [action action] [options]
...
...
Description:
...
To create a controller within a module, specify the controller name as a path like 'parent_module/controller_name'.
...
Example:
`rails generate controller CreditCards open debit credit close`
Credit card controller with URLs like /credit_cards/debit.
Controller: app/controllers/credit_cards_controller.rb
Test: test/controllers/credit_cards_controller_test.rb
Views: app/views/credit_cards/debit.html.erb [...]
Helper: app/helpers/credit_cards_helper.rb
</pre>
</div>
<p>The controller generator is expecting parameters in the form of <code>generate controller ControllerName action1 action2</code>. Let's make a <code>Greetings</code> controller with an action of <strong>hello</strong>, which will say something nice to us.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails generate controller Greetings hello
create app/controllers/greetings_controller.rb
route get 'greetings/hello'
invoke erb
create app/views/greetings
create app/views/greetings/hello.html.erb
invoke test_unit
create test/controllers/greetings_controller_test.rb
invoke helper
create app/helpers/greetings_helper.rb
invoke test_unit
invoke assets
invoke scss
create app/assets/stylesheets/greetings.scss
</pre>
</div>
<p>What all did this generate? It made sure a bunch of directories were in our application, and created a controller file, a view file, a functional test file, a helper for the view, a JavaScript file, and a stylesheet file.</p><p>Check out the controller and modify it a little (in <code>app/controllers/greetings_controller.rb</code>):</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
class GreetingsController < ApplicationController
def hello
@message = "Hello, how are you today?"
end
end
</pre>
</div>
<p>Then the view, to display our message (in <code>app/views/greetings/hello.html.erb</code>):</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<h1>A Greeting for You!</h1>
<p><%= @message %></p>
</pre>
</div>
<p>Fire up your server using <code>rails server</code>.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails server
=> Booting Puma...
</pre>
</div>
<p>The URL will be <a href="http://localhost:3000/greetings/hello">http://localhost:3000/greetings/hello</a>.</p><div class="info"><p>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 <strong>index</strong> action of that controller.</p></div><p>Rails comes with a generator for data models too.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ 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.
</pre>
</div>
<div class="note"><p>For a list of available field types for the <code>type</code> parameter, refer to the <a href="http://edgeapi.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/SchemaStatements.html#method-i-add_column">API documentation</a> for the add_column method for the <code>SchemaStatements</code> module. The <code>index</code> parameter generates a corresponding index for the column.</p></div><p>But instead of generating a model directly (which we'll be doing later), let's set up a scaffold. A <strong>scaffold</strong> 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.</p><p>We will set up a simple resource called "HighScore" that will keep track of our highest score on video games we play.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ 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
</pre>
</div>
<p>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 <code>high_scores</code> table and fields), takes care of the route for the <strong>resource</strong>, and new tests for everything.</p><p>The migration requires that we <strong>migrate</strong>, that is, run some Ruby code (living in that <code>20130717151933_create_high_scores.rb</code>) to modify the schema of our database. Which database? The SQLite3 database that Rails will create for you when we run the <code>rails db:migrate</code> command. We'll talk more about that command below.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails db:migrate
== CreateHighScores: migrating ===============================================
-- create_table(:high_scores)
-> 0.0017s
== CreateHighScores: migrated (0.0019s) ======================================
</pre>
</div>
<div class="info"><p>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
<a href="https://guides.rubyonrails.org/testing.html">the testing guide</a> for an in-depth
look at unit testing.</p></div><p>Let's see the interface Rails created for us.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails server
</pre>
</div>
<p>Go to your browser and open <a href="http://localhost:3000/high_scores">http://localhost:3000/high_scores</a>, now we can create new high scores (55,160 on Space Invaders!)</p><h4 id="rails-console"><a class="anchorlink" href="#rails-console">1.4 <code>rails console</code></a></h4><p>The <code>console</code> command lets you interact with your Rails application from the command line. On the underside, <code>rails console</code> 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.</p><div class="info"><p>You can also use the alias "c" to invoke the console: <code>rails c</code>.</p></div><p>You can specify the environment in which the <code>console</code> command should operate.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails console -e staging
</pre>
</div>
<p>If you wish to test out some code without changing any data, you can do that by invoking <code>rails console --sandbox</code>.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ 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>
</pre>
</div>
<h5 id="the-app-and-helper-objects"><a class="anchorlink" href="#the-app-and-helper-objects">1.4.1 The app and helper objects</a></h5><p>Inside the <code>rails console</code> you have access to the <code>app</code> and <code>helper</code> instances.</p><p>With the <code>app</code> method you can access url and path helpers, as well as do requests.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
>> app.root_path
=> "/"
>> app.get _
Started GET "/" for 127.0.0.1 at 2014-06-19 10:41:57 -0300
...
</pre>
</div>
<p>With the <code>helper</code> method it is possible to access Rails and your application's helpers.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
>> helper.time_ago_in_words 30.days.ago
=> "about 1 month"
>> helper.my_custom_helper
=> "my custom helper"
</pre>
</div>
<h4 id="rails-dbconsole"><a class="anchorlink" href="#rails-dbconsole">1.5 <code>rails dbconsole</code></a></h4><p><code>rails dbconsole</code> 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.</p><div class="info"><p>You can also use the alias "db" to invoke the dbconsole: <code>rails db</code>.</p></div><h4 id="rails-runner"><a class="anchorlink" href="#rails-runner">1.6 <code>rails runner</code></a></h4><p><code>runner</code> runs Ruby code in the context of Rails non-interactively. For instance:</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails runner "Model.long_running_method"
</pre>
</div>
<div class="info"><p>You can also use the alias "r" to invoke the runner: <code>rails r</code>.</p></div><p>You can specify the environment in which the <code>runner</code> command should operate using the <code>-e</code> switch.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails runner -e staging "Model.long_running_method"
</pre>
</div>
<p>You can even execute ruby code written in a file with runner.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails runner lib/code_to_be_run.rb
</pre>
</div>
<h4 id="rails-destroy"><a class="anchorlink" href="#rails-destroy">1.7 <code>rails destroy</code></a></h4><p>Think of <code>destroy</code> as the opposite of <code>generate</code>. It'll figure out what generate did, and undo it.</p><div class="info"><p>You can also use the alias "d" to invoke the destroy command: <code>rails d</code>.</p></div><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ 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
</pre>
</div>
<div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ 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
</pre>
</div>
<h4 id="rails-about"><a class="anchorlink" href="#rails-about">1.8 <code>rails about</code></a></h4><p><code>rails about</code> 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.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ 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
</pre>
</div>
<h4 id="rails-assets"><a class="anchorlink" href="#rails-assets">1.9 <code>rails assets:</code></a></h4><p>You can precompile the assets in <code>app/assets</code> using <code>rails assets:precompile</code>, and remove older compiled assets using <code>rails assets:clean</code>. The <code>assets:clean</code> command allows for rolling deploys that may still be linking to an old asset while the new assets are being built.</p><p>If you want to clear <code>public/assets</code> completely, you can use <code>rails assets:clobber</code>.</p><h4 id="rails-db"><a class="anchorlink" href="#rails-db">1.10 <code>rails db:</code></a></h4><p>The most common commands of the <code>db:</code> rails namespace are <code>migrate</code> and <code>create</code>, and it will pay off to try out all of the migration rails commands (<code>up</code>, <code>down</code>, <code>redo</code>, <code>reset</code>). <code>rails db:version</code> is useful when troubleshooting, telling you the current version of the database.</p><p>More information about migrations can be found in the <a href="active_record_migrations.html">Migrations</a> guide.</p><h4 id="rails-notes"><a class="anchorlink" href="#rails-notes">1.11 <code>rails notes</code></a></h4><p><code>rails notes</code> searches through your code for comments beginning with a specific keyword. You can refer to <code>rails notes --help</code> for information about usage.</p><p>By default, it will search in <code>app</code>, <code>config</code>, <code>db</code>, <code>lib</code>, and <code>test</code> directories for FIXME, OPTIMIZE, and TODO annotations in files with extension <code>.builder</code>, <code>.rb</code>, <code>.rake</code>, <code>.yml</code>, <code>.yaml</code>, <code>.ruby</code>, <code>.css</code>, <code>.js</code>, and <code>.erb</code>.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ 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]
</pre>
</div>
<h5 id="annotations"><a class="anchorlink" href="#annotations">1.11.1 Annotations</a></h5><p>You can pass specific annotations by using the <code>--annotations</code> argument. By default, it will search for FIXME, OPTIMIZE, and TODO.
Note that annotations are case sensitive.</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ 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]
</pre>
</div>
<h5 id="directories"><a class="anchorlink" href="#directories">1.11.2 Directories</a></h5><p>You can add more default directories to search from by using <code>config.annotations.register_directories</code>. It receives a list of directory names.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
config.annotations.register_directories("spec", "vendor")
</pre>
</div>
<div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ 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
</pre>
</div>
<h5 id="extensions"><a class="anchorlink" href="#extensions">1.11.3 Extensions</a></h5><p>You can add more default file extensions to search from by using <code>config.annotations.register_extensions</code>. It receives a list of extensions with its corresponding regex to match it up.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
config.annotations.register_extensions("scss", "sass") { |annotation| /\/\/\s*(#{annotation}):?\s*(.*)$/ }
</pre>
</div>
<div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ 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
</pre>
</div>
<h4 id="rails-routes"><a class="anchorlink" href="#rails-routes">1.12 <code>rails routes</code></a></h4><p><code>rails routes</code> 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.</p><h4 id="rails-test"><a class="anchorlink" href="#rails-test">1.13 <code>rails test</code></a></h4><div class="info"><p>A good description of unit testing in Rails is given in <a href="testing.html">A Guide to Testing Rails Applications</a></p></div><p>Rails comes with a test framework called minitest. Rails owes its stability to the use of tests. The commands available in the <code>test:</code> namespace helps in running the different tests you will hopefully write.</p><h4 id="rails-tmp"><a class="anchorlink" href="#rails-tmp">1.14 <code>rails tmp:</code></a></h4><p>The <code>Rails.root/tmp</code> directory is, like the *nix /tmp directory, the holding place for temporary files like process id files and cached actions.</p><p>The <code>tmp:</code> namespaced commands will help you clear and create the <code>Rails.root/tmp</code> directory:</p>
<ul>
<li>
<code>rails tmp:cache:clear</code> clears <code>tmp/cache</code>.</li>
<li>
<code>rails tmp:sockets:clear</code> clears <code>tmp/sockets</code>.</li>
<li>
<code>rails tmp:screenshots:clear</code> clears <code>tmp/screenshots</code>.</li>
<li>
<code>rails tmp:clear</code> clears all cache, sockets, and screenshot files.</li>
<li>
<code>rails tmp:create</code> creates tmp directories for cache, sockets, and pids.</li>
</ul>
<h4 id="miscellaneous"><a class="anchorlink" href="#miscellaneous">1.15 Miscellaneous</a></h4>
<ul>
<li>
<code>rails stats</code> is great for looking at statistics on your code, displaying things like KLOCs (thousands of lines of code) and your code to test ratio.</li>
<li>
<code>rails secret</code> will give you a pseudo-random key to use for your session secret.</li>
<li>
<code>rails time:zones:all</code> lists all the timezones Rails knows about.</li>
</ul>
<h4 id="custom-rake-tasks"><a class="anchorlink" href="#custom-rake-tasks">1.16 Custom Rake Tasks</a></h4><p>Custom rake tasks have a <code>.rake</code> extension and are placed in
<code>Rails.root/lib/tasks</code>. You can create these custom rake tasks with the
<code>rails generate task</code> command.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
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
</pre>
</div>
<p>To pass arguments to your custom rake task:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
task :task_name, [:arg_1] => [:prerequisite_1, :prerequisite_2] do |task, args|
argument_1 = args.arg_1
end
</pre>
</div>
<p>You can group tasks by placing them in namespaces:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
namespace :db do
desc "This task does nothing"
task :nothing do
# Seriously, nothing
end
end
</pre>
</div>
<p>Invocation of the tasks will look like:</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails task_name
$ rails "task_name[value 1]" # entire argument string should be quoted
$ rails db:nothing
</pre>
</div>
<div class="note"><p>If your need to interact with your application models, perform database queries, and so on, your task should depend on the <code>environment</code> task, which will load your application code.</p></div><h3 id="the-rails-advanced-command-line"><a class="anchorlink" href="#the-rails-advanced-command-line">2 The Rails Advanced Command Line</a></h3><p>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.</p><h4 id="rails-with-databases-and-scm"><a class="anchorlink" href="#rails-with-databases-and-scm">2.1 Rails with Databases and SCM</a></h4><p>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.</p><p>Let's see what a <code>--git</code> option and a <code>--database=postgresql</code> option will do for us:</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ 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'
</pre>
</div>
<p>We had to create the <strong>gitapp</strong> 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:</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ 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
...
...
</pre>
</div>
<p>It also generated some lines in our <code>database.yml</code> configuration corresponding to our choice of PostgreSQL for database.</p><div class="note"><p>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 <code>rails new</code> command to generate the basis of your app.</p></div>
<h3>Feedback</h3>
<p>
You're encouraged to help improve the quality of this guide.
</p>
<p>
Please contribute if you see any typos or factual errors.
To get started, you can read our <a href="https://edgeguides.rubyonrails.org/contributing_to_ruby_on_rails.html#contributing-to-the-rails-documentation">documentation contributions</a> section.
</p>
<p>
You may also find incomplete content or stuff that is not up to date.
Please do add any missing documentation for master. Make sure to check
<a href="https://edgeguides.rubyonrails.org">Edge Guides</a> first to verify
if the issues are already fixed or not on the master branch.
Check the <a href="ruby_on_rails_guides_guidelines.html">Ruby on Rails Guides Guidelines</a>
for style and conventions.
</p>
<p>
If for whatever reason you spot something to fix but cannot patch it yourself, please
<a href="https://github.com/rails/rails/issues">open an issue</a>.
</p>
<p>And last but not least, any kind of discussion regarding Ruby on Rails
documentation is very welcome on the <a href="https://groups.google.com/forum/#!forum/rubyonrails-docs">rubyonrails-docs mailing list</a>.
</p>
</div>
</div>
</div>
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<p>This work is licensed under a <a href="https://creativecommons.org/licenses/by-sa/4.0/">Creative Commons Attribution-ShareAlike 4.0 International</a> License</p>
<p>"Rails", "Ruby on Rails", and the Rails logo are trademarks of David Heinemeier Hansson. All rights reserved.</p>
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