Navigating the Source - Developer Guide | Spree Commerce

This guide covers obtaining and running the source code. This is primarily for developers who are interested in contributing code to the Spree project or fixing the source code themselves. It is not necessary to have a copy of the source code to run Spree. This guide covers the following topics:

• How Spree uses Git and GitHub to manage source code
• The various gems that comprise the Spree source code
• Building the gem from the source

Git

The Spree source code is currently maintained in a Git repository. Git is a distributed version control system (DVCS)

The authoritative git repository is hosted by GitHub and is located in the spree repository. You can clone the git repository using the following command:

$ git clone git://github.com/spree/spree.git

Browsing the Repository and/or Downloading the Source Code

You can easily browse the repository through GitHub’s excellent visual interface. GitHub also contains a link to download a tarball copy of the latest source code as well as links to previous versions.

Git on Windows

There are some well developed Git clients for Windows now. If you are on a Windows box you might want to check out the msysgit project.

Monitoring Changes in the Source

If you would like to keep up to date on changes to the source you can subscribe to the GitHub RSS feed and you will be notified of all the commits.

Bundler

Spree uses the very excellent bundler gem to manage its dependencies. We are assuming you have basic familiarity with bundler. A detailed explanation of bundler can be found on Bundler’s site.

You can install the gem dependencies for Spree after cloning the repository using this Bundler-provided command:

$ bundle install

This allows you to quickly and painlessly have the exact gem depedencies you need to work with Bundler.

Layout and Structure

Collection of Gems

The Spree gem itself is very minimal and consists mostly of a collection of gems. These gems are maintained together in a single GitHub repository and new versions of the gems are shipped with each new Spree release. The official documentation (which you are reading now) covers functionality provided by each of these gems.

Within the Spree source, each of the gems is organized into subdirectories as follows:

Use of Rails Engines

Each of the gems in Spree makes use of Rails Engines. This functionality was introduced in Rails 3.0 and allows Engines to behave in a manner similar to fully-functional applications. Relying on this mechanism provides several advantages:

An Intuitive Mechanism for Customization

Default Spree functionality is provided via the Rails engine gems. Engines can provide several aspects traditionally associated with a Rails application including (but not limited to):

• Models, views and controllers
• Routes
• Helpers
• Rake tasks
• Generators
• Locales

All of these elements can be overridden in the main Rails application. Therefore, it is relatively simple to add Spree to your Rails application and then customize it further by supplying your own elements in that same application. A full discussion of Rails Engines is not appropriate here. Please consult the Rails Guides for more information.

Simple Distribution and Installation as Gems

Using a Spree gem is as simple as adding it to your Gemfile:

gem 'spree_core', '2.1.0'

Distribution of Spree (and its extensions) is also consistent with Rails standards and modularity (see next.)

Consistency With a Rails Standard

Prior to version 0.30.0, Spree used a complex custom mechanism for implementing “engine-like” functionality. While it was difficult to strip this functionality out of Spree, the benefits are well worth it. Spree now receives all of the massive testing and attention to detail that comes for free when using the Rails core engine functionality, rather than a custom solution.

Modularity

There are differing opinions on what belongs in the “core.” People often express their opinion that Spree is either “getting too fat” or “lacks basic features.” By relying on these engines (and distributing them as gems), developers are free to use only the parts of Spree that they find useful. For instance, this would allow you to omit promotions functionality or to replace the authentication mechanism.

For example, if you were to specify something like this in your application’s Gemfile:

gem 'spree', '2.1.0'

It would require all the individual parts of Spree. However, if you only wanted to require the “core” and “backend” parts of Spree, you would do this:

gem 'spree_core', '2.1.0'
gem 'spree_backend', '2.1.0'

Building a Sandbox Application

When working with the Spree source you may find yourself wanting to see how the code performs in the context of an actual application. This is due to the fact that Spree is intended to be distributed as a gem and is not designed to be run as a standalone application. Spree includes a helpful Rake task for setting up such a test application.

To run this Rake task, go into the root of the Spree project and run this command:

$ bundle exec rake sandbox

This will create a barebones rails application configured with the Spree gem. It runs the migrations for you and sets up the sample data. The resulting sandbox folder is already ignored by .gitignore and it is deleted and rebuilt from scratch each time the Rake task runs.

Building the Gem from the Source

The Spree gem can easily be built from the source. Run these two commands in the root of the Spree project to do this:

$ bundle exec rake clean
$ bundle exec rake gem

Most likely you will want to build and install all of the related gems. Fortunately, there is a simple Rake task for that.

$ bundle exec rake gem:install

You can also build just one specific gem.

$ cd core
$ bundle exec rake gem

Tips for Working with the Source

Using the “Edge” Code

If you are interested in simply using the latest edge code (as opposed to contributing to it) then the simplest thing to do is add a :github directive to your Gemfile and point it at the master branch.

gem 'spree', :github => 'spree/spree'

This will effectively use the latest code from the Git repository at the time you run bundle install. This version of the code will be “frozen” in your Gemfile.lock and will ensure that anyone else using your project code is using the exact same version of the Spree code as you are. You will need to update the bundle if you want to update to code that is newer since the last time you updated.

$ bundle update

Developing on the “Edge”

If you plan on using the edge code but also contributing back to Spree, then you may be interested in the following approach. Create your Rails app that will be using the Spree gem in a directory that has the same parent as a locally cloned version of the Spree source. Then simply use the following in your Gemfile.

gem 'spree', :path => '../spree'

“-stable” branches

The Spree Git repository also contains stable branches for each minor Spree version. For instance, there is a 2-1-stable branch which contains the latest work for the 2.1.x branch of Spree. You may also decide to use this branch if you want the latest and greatest version of Spree:

gem 'spree', :github => 'spree/spree', :branch => '2-1-stable'

Similarly, all main Spree extensions use this versioning scheme as well. For example, here’s a line that would be used for spree_auth_devise:

gem 'spree_auth_devise', :github => 'spree/spree_auth_devise', :branch => '2-1-stable'

Creating Extensions

Spree provides a convenient generator for helping you to get started with extensions.

$ spree extension foo

Please see the Creating Extensions guide for more details.