shopify-sinatra-app

"A classy shopify app"

Getting Started

Install the gem:

gem install shopify-sinatra-app

or build from source

gem build shopify-sinatra-app.gemspec
gem install shopify-sinatra-app-X.X.X.gem

To create a new app use the generator:

shopify-sinatra-app-generator new <your new app name>

This will create a new skeleton shopify-sinatra-app. The generator will create several default files for you rather than having them bundled in the sinatra extension - its worthwhile to read this section to understand what each of these files is for.

config/database.yml --> The database config for active record. Initially this is setup to use sqlite3 for development and testing which you may want to change to mimic your production database.

.env --> a hidden file not tracked by source control for storing credentials etc. to be set as environment variables

config.ru --> Rackup file - describes how to run a rack based app

Gemfile --> manages the dependencies of the app

lib/app.rb --> This file is the skeleton app file. More details on how to use the methods provided by this extension are given in the following section.

Procfile --> Specific for deploying to Heroku, this file tells heroku how to run the app

public/icon.png --> This icon file is used by the Shopify Embedded App SKD and is shown in the menu bar of your embedded app

Rakefile --> includes some helper methods etc for running and managing the app. Standard for ruby based projects

views/layouts/appliction.erb --> This is the layout file that all templates will use unless otherwise specified. It sets up some defaults for using the Shopify Embedded App SDK and Twitter Bootstrap for styling

views/_top_bar.erb --> This is a partial view that describes the top bar inside a Shopify Embedded App. It also has some code to forward flash messages to the Embedded App SKD

views/* --> The other views used by the app. You'll probably make a lot of changes to home.erb and install.erb to customize the experience for your app

Setting the app to use your Shopify API credentials

You'll need to create a Shopify Partner Account and a new application. You can make an account here and see this tutorial for creating a new application.

Note - The shopify-sinatra-app creates an embedded app! You need change the embedded setting to enabled in the Shopify Partner area for your app. If you don't want your app to be embedded then remove the related code in layout/application.erb and delete the layout/_top_bar.erb file and the references to it in the other views.

After creating your new application you need to edit the .env file and add the following lines:

SHOPIFY_API_KEY=<your api key>
SHOPIFY_SHARED_SECRET=<your shared secret>
SECRET=<generate a random string to encrypt credentials with>

Shopify::Methods

shopify_session - The main method of the framework, most of your routes will use this method to acquire a valid shopify session and then perform api calls to Shopfiy. The method activates a Shopify API session for you and accepts a block inside of which you can use the ShopifyAPI. Here is an example endpoint that displays products:

get '/products.json' do
  shopify_session do
    products = ShopifyAPI::Product.all(limit: 5)
    products.to_json
  end
end

webhook_session - This method is for an endpoint that recieves a webhook from Shopify. Webhooks are a great way to keep your app in sync with a shop's data without polling. You can read more about webhooks here. This method also takes a block of code and makes the webhook data available as a hash (note only works for json webhooks, don't use xml). Here is an example that listens to a order creation webhook:

post '/order.json' do
  webhook_session do |webhook_data|
    # do something with the data
  end
end

webhook_job - Its impossible to control the flow of webhooks to your app from Shopify especially if a larger store installs your app or if a shop has a flash sale. To prevent your app from getting overloaded with webhook requests it is usually a good idea to process webhooks in a background queue and return a 200 to Shopify immediately. This method provides this functionality using redis and resque. This method takes the name of a job class whose perform method expects a shop_name, shop_token and the webhook data as a hash. The session method is useful for prototpying and experimenting but production apps should use webhook_job. Here is an example:

post '/order.json' do
  webhook_job(OrderWebhookJob)
end

class OrderWebhookJob
  @queue = :default

  def self.perform(shop_name, shop_token, webhook_data)
    # do something with the data
  end
end

install - This is a private method provided with the framework that gets called when the app is authorized for the first time. You should fill this method in with anything you need to initialize on install, for example webhooks and services on shopify or any other database models you have created specific to a shop.

logout - This method clears the current session data in the app

current_shop - Returns the name of the current shop (format: example.myshopify.com)

base_url - This returns the url of the app

shopify-sinatra-app also includes rack-flash3 and the flash messages are forwarded to the Shopify Embedded App SDK. Flash messages are useful for signalling to your users that a request was successful without changing the page. The following is an example of how to use a flash message in a route:

post '/flash_message' do
  flash[:notice] = "Flash Message!"
  redirect '/'
end

note - a flash must be followed by a redirect or it won't work!

Developing

To run the app locally we use foreman which comes with the Heroku Toolbelt. Foreman handles running our application and setting our credentials as environment variables. To run the application type:

foreman start -p 4567

Debugging ...

You can set the application url in the Shopify Partner area to be http://localhost:4567/ which will allow you to install your app on a live shop while running it locally.

While running the app locally you'll be able to test the install and other routes because your browser is aware of your local application but if you want to test a route that listens to a webhook this will not work because Shopify cannot talk to your local web application. You could expose your local application to the web but an easier solution is to use a tool called Ngrok. Download Ngrok and run it on port 4567 (or whichever port you are using):

./ngrok 4567

Ngrok will report what address your app is available at, leave Ngrok running and then create your webhook to point to the ngrok url plus your route e.g. <ngrok url>/webhook_test.json. Now trigger the webhook you are testing and it will get forwarded through ngrok to your local web application allowing you to use debuggers and repls to complete your code.

When developing locally you'll need to enable unsafe javascripts in your browser for the Embedded App SDK to function. Read more here.

Deploying

This template was created with deploying to Heroku in mind. Heroku is a great cloud based app hosting provider that makes it incredibly easy to get an application into a product environment.

Before you can get started with Heroku you need to create a git repo for you application:

git init
git add .
git commit -m "initial commit"

Now you can create a new heroku application. Download the Heroku Toolbelt and run the following command to create a new application:

heroku apps:create <your new app name>

You will also need to add the following (free) add-ons to your new Heroku app:

heroku addons:add heroku-postgresql
heroku addons:add rediscloud

Now we can deploy the new application to Heroku. Deploying to Heroku is as simple as pushing the code using git:

git push heroku master

A rake deploy2heroku command is included in the generated Rakefile which does just this.

Now that our application is deployed we need to run rake db:migrate to initialize our database on Heroku. To do this run:

heroku run rake db:migrate

We also need to set our environment variables on Heroku. The environment variables are stored in .env and are not tracked by git. This is to protect your credentials in the case of a source control breach. Heroku provides a command to set environment variables: heroku config:set VAR=foo. In the generated Rakefile there is a helper method that will properly set all the variables in your .env file:

rake creds2heroku

and make sure you have at least 1 dyno for web and resque:

heroku scale web=1 resque=1

Note - if you are not using any background queue for processing webhooks then you do not need the redis add-on or the resque dyno so you can set it to 0.

Make sure you set your shopify apps url to your Heroku app url (and make sure to use the https version or else the Embedded App SDK won't work) in the Shopify Partner area https://app.shopify.com/services/partners/api_clients.

Contributing

PRs welcome!