The best way to go through this course is to follow it step by step. All steps are essential to run this example application and no additional code or steps are needed.
By following along with this guide, you'll create a Rails project called blog, a (very) simple weblog. Before you can start building the application, you need to make sure that you have Rails itself installed.
The examples below use$to represent your terminal prompt in a UNIX-like OS, though it may have been customized to appear differently. If you are using Windows, your prompt will look something likec:\source_code>
Before you install Rails, you should check to make sure that your system has the proper prerequisites installed. These include Ruby and SQLite3.
Open up a command line prompt. On macOS open Terminal.app, on Windows choose "Run" from your Start menu and type 'cmd.exe'. Any commands prefaced with a dollar sign $ should be run in the command line. Verify that you have a current version of Ruby installed:
$ ruby -vruby 2.3.1p112
Rails requires Ruby version 2.2.2 or later. If the version number returned is less than that number, you'll need to install a fresh copy of Ruby.
A number of tools exist to help you quickly install Ruby and Ruby on Rails on your system. Windows users can use Rails Installer, while macOS users can use Tokaido. For more installation methods for most Operating Systems take a look at ruby-lang.org.
If you are working on Windows, you should also install the Ruby Installer Development Kit.
You will also need an installation of the SQLite3 database. Many popular UNIX-like OSes ship with an acceptable version of SQLite3. On Windows, if you installed Rails through Rails Installer, you already have SQLite installed. Others can find installation instructions at the SQLite3 website. Verify that it is correctly installed and in your PATH:
$ sqlite3 --version
The program should report its version.
To install Rails, use the gem install command provided by RubyGems:
$ gem install rails
To verify that you have everything installed correctly, you should be able to run the following:
$ rails --version
If it says something like "Rails 5.1.1", you are ready to continue.
Rails comes with a number of scripts called generators that are designed to make your development life easier by creating everything that's necessary to start working on a particular task. One of these is the new application generator, which will provide you with the foundation of a fresh Rails application so that you don't have to write it yourself.
To use this generator, open a terminal, navigate to a directory where you have rights to create files, and type:
$ rails new blog
This will create a Rails application called Blog in a blog directory and install the gem dependencies that are already mentioned in Gemfile using bundle install.
If you're using Windows Subsystem for Linux then there are currently some limitations on file system notifications that mean you should disable the spring and listen gems which you can do by running rails new blog --skip-spring --skip-listen.
You can see all of the command line options that the Rails application builder accepts by running rails new -h.
After you create the blog application, switch to its folder:
$ cd blog
The blog directory has a number of auto-generated files and folders that make up the structure of a Rails application. Most of the work in this tutorial will happen in the app folder, but here's a basic rundown on the function of each of the files and folders that Rails created by default: