Project: Your First Rails Application


With Ruby installed, you’re all set to create your first Ruby on Rails application!

Before continuing, let’s review a few best practices to keep in mind:

  • Follow the directions closely, and don’t skip over any sections.
  • Do NOT use sudo unless The Odin Project specifically says to do so. Failing to follow this advice can cause a lot of headaches. In some instances, you might see a message in the terminal telling you to use sudo and/or to install something with apt. Ignore what the terminal says and follow the instructions below.
  • Copy and paste the commands to avoid typos.
  • If you stop working on this project partway through and come back to it later, be sure to use cd to move back inside your project directory so that the commands will work.

In this project, we’re going to build a fully functional Rails application. The entire point of this exercise is to make sure that you have everything installed and working correctly on your computer. Do not worry if you don’t fully understand what you’re doing. You’ll learn exactly what all of these commands are doing later on in the course. For now, go slowly, and be sure to follow each and every step closely. If you run into trouble, don’t forget that you can always reach out for help on Discord.

Reminder: In this lesson you’ll see shaded boxes that contain text like the one below.


Those are terminal commands and you’ll need to enter them on the terminal in your operating system. Forgot how to open your terminal? Try googling “how to open terminal in [your operating system]”.

Your First Rails App

Step 1: Create Your First Ruby on Rails Web Application

Don’t worry if you don’t totally understand what you are doing in these next steps. You will learn what all of this does later in The Odin Project curriculum. As long as the commands complete successfully, just keep going. The main reason we’re doing this is to ensure everything is properly installed and configured.

Step 1.1: Install Rails and Bundler

We’ve previously installed Ruby, and now it’s time to install Ruby on Rails. It’s as simple as running one command!

gem install rails -v 5.2.3

Step 1.2: Lay the Groundwork

Next, if you haven’t already done it, we need to create a directory that will house our project. You can name it anything you like!

NOTE TO WSL USERS: If you are on WSL, you MUST cd into your Projects folder to avoid issues.

mkdir odin_on_rails

Then, move into the new directory:

cd odin_on_rails

Step 1.3: Create the Application

This is where things might become more foreign. If you don’t understand what’s going on, just double check that you’re typing in the correct commands and keep going. This section is meant to expose you to the process and to verify that everything is working. Again, it’s OK to not understand what’s going on at this point.

We’re going to start by telling Rails to initialize the application for us. Then, we’ll tell Rails to create a template for us so that we can get up and running.

rails new my_first_rails_app

This will do a bunch of things, and you’ll see a lot of output in the terminal. If everything worked, you should see something similar to this in the last few lines of output:

Bundle complete! 18 Gemfile dependencies, 79 gems now installed.
Use `bundle info <gem name>` to see where a bundled gem is installed.

In the above process, Rails created a new directory for us. Let’s cd into it now:

cd my_first_rails_app

Now, we’re going to tell Rails to generate some templates for us. This will get us up and running in no time at all.

rails generate scaffold car make:string model:string year:integer

After generating the scaffolds, we need to migrate the database.

rails db:migrate

Step 1.4: Start Up Your App

Now that you have created a Rails application, you can start it up and see if it works!

In the terminal, type

rails server

Now, go to your browser and visit http://localhost:3000/cars to see your application! Go ahead and create a new car, and then refresh the page to verify it is working. Add as many cars as you’d like!

When you’re satisfied, go back to the terminal where Rails is running, and type Ctrl + C to end the application.

Step 2: Initialize Git and Push to GitHub

To push our app to GitHub and Heroku, we need to use Git.

Step 2.1: Initialize git

To tell Git we want to use version control on the directory we are in, we need to initialize it.

Verify you’re in the my_first_rails_app directory by using the pwd (print working directory) command.

$ pwd

Then, initialize the Git repo (short for “repository”):

git init

Step 2.2: Commit Changes

Now that Git is initialized, we need to tell Git to save all the files we have. First, we add our files to the staging area, which temporarily holds files before committing them. Don’t worry if you don’t understand all of this right now.

To stage all our files, type

git add .

Then, we’ll commit the files. Be sure to include the quotation marks.

git commit -m "initial commit"

Step 2.3: Connect the Local Repository to the Remote Repository

At this point, we have our files on our own computer and can track changes made to our files over time. But what if we want to share the files with another computer or have multiple people work on the same project? For this functionality, we need a GitHub repository.

First, open in your browser and sign in (if you aren’t already). Next, look for your profile picture in the upper right-hand corner, click the “+” symbol next to it, and then click New repository. Give the repository a name (maybe my_first_rails_app?), and then click Create Repository.

On the next page, you’ll see a bunch of commands listed. We’re really only interested in the SSH URL at the top, so double check that SSH has been selected and then copy the URL.

Now, switch back over to the terminal to connect the project and GitHub by running two simple commands:

NOTE: Do not enter the < or > symbols. Replace those symbols and everything between them with the URL that you copied from GitHub.

git remote add origin <SSH URL from above>
git push -u origin master

Remember to replace <SSH URL from above> with the URL that you copied.

The terminal will start its work, pausing to verify your connection to GitHub.

A message from Github stating, “The authenticity of host ‘’…” may appear during this process. You can type yes and hit Enter to continue.

After the terminal finishes its magic, return to your GitHub repository and refresh the page. You should see a lot of files, starting with a folder called “app”.

This marks the start of your Odin journey! Later on, you’ll be able to look back at this repository and marvel over how far you’ve come!

Step 3: Deploy Your Rails Application

Now that you’ve created your first Rails application, it’s time to deploy it so that you can show the whole world! This process will allow you to send a link to people so they can see your app working.

Step 3.1: Create a Heroku Account

Go to the Heroku website and create an account using the same email address you used for GitHub and Git.

Step 3.2: Heroku CLI

Activate your account from the email they sent you. Now, we’ll install the Heroku command line so that we can interact with the Heroku service. We will use curl to download a script and run it to install the Heroku CLI. This script may ask for your sudo password, this is expected. Go ahead and type it in after running the command below.

Run this command:

curl | sh

This command needs administrative access and will ask for your sudo password. Enter the password of your computer account and press enter to continue.

Then, type heroku version, which should return something similar to heroku/7.5.1 linux-x64 node-v10.5.0.

Step 3.3: Add your SSH Key to Heroku

Adding your SSH key lets Heroku know what machine the commands are coming from, similar to how GitHub uses SSH keys.

In your terminal, type

heroku keys:add

Next, press y and then Enter. Now, type in the email address you used to create your Heroku account and press Enter. Then, type in the password for your Heroku account. Next, press y and Enter to allow Heroku to upload your public SSH key.

The terminal may read Invalid credentials provided. Just press any key and the Heroku website will open in your browser. Log in with the information you created your account with, and the terminal will reappear and accept your public SSH key.

Step 3.4: Create a Heroku Application

First, run

heroku create

Then, run

git remote

Verify that you see heroku in the output.

Step 3.5: Prepare Rails for Heroku Deployment

Heroku uses a slightly different setup than what we have on our machine. We need to configure the application to play nicely with both.

Step 3.5.1: Configure the Gemfile

To deploy a Rails application, we need to change some settings.

First, we need to open the Gemfile and edit it.

In your terminal, type ls and verify that you see Gemfile in the output. If you don’t see it, navigate to the directory you created in Steps 2.2 and 2.3.

Then, we’ll use VSCode to modify the Gemfile. Open your app in VSCode by typing code . (NOTE: The period at the end is important!) (WSL users: If you type code . and you see system32 in the top left, you have created your application outside of the Projects directory we created earlier.)

When VSCode opens, you should see a list of files on the left side of the screen. Click on Gemfile to open it in the editor. Then, delete the line that says,

gem 'sqlite3'

Replace the line you just deleted with the following:

group :development, :test do
 gem 'sqlite3'

group :production do
  gem 'pg'

Then, save the file. You can leave VSCode open since we’re going to be coming back to it, but for the next step, go back to your terminal.

Step 3.5.2: Install the Bundle

Next, we need to tell Ruby, Git, and Heroku that we’ve changed the Gemfile. To do this, we can simply run

bundle install --without production

Step 3.5.3: Configure the Root Route

The next thing we need to edit is the routes.rb file to set our root route. We’re going to do this so that we can see the application without having to append /cars at the end of the URL.

Go back to VSCode and expand the config folder in the file list at the left-hand side of the screen. One of the files inside the folder will be named routes.rb. Open routes.rb and make it match the example below:

Rails.application.routes.draw do
  root 'cars#index'
  resources :cars

Save the file. You can close VSCode now; the rest of the steps take place in the terminal.

Step 3.6: Add Changes to Git

Now that we have made some changes, we need to tell Git. This step is also required to successfully deploy to Heroku.

First, we’ll check which files have been updated by running

git status

The output should look similar to the example below:

$ git status
On branch master
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

	modified:   Gemfile
	modified:   Gemfile.lock
	modified:   config/routes.rb

no changes added to commit (use "git add" and/or "git commit -a")

Great! Now, let’s add the changes to staging:

git add .

Then, commit the files in staging:

git commit -m 'updates for heroku deployment'

While we’re here, we might as well push our changes to GitHub too:

git push origin master

Step 3.7: Push to Heroku

Now that we’ve commited the files, we can push to Heroku:

git push heroku master

UPDATE 2019-01-04: If you run into an error on the next command stating that you need to use Bundler 2 or greater with this lockfile, you’ll need to run:

heroku buildpacks:set

and then run the git push heroku master command again.

This will send the app you created to Heroku. There will be a lot of output in your console. Wait for it to finish.

Step 3.8: Migrate the Database on Heroku

Similar to what we did locally before we launched our app, we need to migrate the database on Heroku, which we can do with the Heroku CLI.

Run this command:

heroku run rails db:migrate

You might see some strange output, but as long as you do not have an error, you have successfully deployed a Rails application!

If you have an error, come to our chat room, and ask for help. Be sure to include the entire output from your terminal when you ask your question.

Step 3.9: Visit Your New Application

It’s time to see your app on the web! If you are not using WSL, to quickly open your app, type

heroku open

and play around with it!

Step 4: Let us know how it went!

You have successfully completed the installations. Congratulations!!! This was the hardest part of the entire Odin Project.

You probably felt like you were in way over your head, and you probably didn’t understand much of what you were doing. That’s 100% normal. Hang in there. You can do this! And we’ve got your back.

Web Development 101

Project: Your First Rails Application

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