Exchange

Exchange aspires to be responsible for the various types of e-commerce interactions available on the Artsy platform. It's currently a prototype, with legacy e-commerce still handled by Gravity. It uses Ruby, Rails, Postgresql, and exposes a GraphQL API.

Meta

• State: production
• Production: https://exchange.artsy.net, Admin Dashboard | Sidekiq Dashboard
• Staging: https://exchange-staging.artsy.net, Admin Dashboard | Sidekiq Dashboard
• GitHub: https://github.com/artsy/exchange/
• Point People: @ashkan18, @williardx
• CI/Deploys: CircleCi; merged PRs to artsy/exchange#master are automatically deployed to staging; PRs from staging to release are automatically deployed to production. Start a deploy...

Setup

• Fork the project to your GitHub account

• Clone your fork:

  $ git clone [email protected]:your-github-username/exchange.git
  

• Install bundles:

  $ bundle install
  

Tests

Once setup, you can run the tests like this:

$ bundle exec rspec

Starting Server

If this is your first time starting the app, make sure your database is setup first by running:

rails db:create
rails db:setup

Then run Procfile.dev via foreman to start the web (rails) and worker (sidekiq) services:

foreman start -f Procfile.dev

Did You Change Models?

Papertrail Audit Logging

As Exchange persists important financial information, we use the PaperTrail gem to maintain a log of data changes to important models within the main relational database.

Exchange implements a slightly-customized, but supported, installation of PaperTrail. By default, PaperTrail writes audit log records to a single versions table. In Exchange, we write audit logs into model-namespaced tables. For example, the audit log for Order records are in the order_versions table and the audit log for Offer records are in the offer_versions table.

Why do we do this? It'll allow PostgreSQL to query across smaller sets of data when operating against the audit log for a particular model.

How to implement this pattern for future models:

1. Include the versioned model shared example in the spec for your model:

  # spec/models/foo_spec.rb
  describe Foo, type: :model do
    ...
    it_behaves_like 'a papertrail versioned model', :foo
    ...
  end

1. Ensure that a Fabricator factory exists for your model:

  # spec/fabricators/foo_fabricator.rb
  Fabricator(:foo) do
    # define enough attributes to have a `valid?` instance of `Foo`
  end

1. Include the customized PaperTrail DSL in your model (provides #versions):

  # app/models/foo.rb
  class Foo < ApplicationRecord
    has_paper_trail versions: { class_name: 'PaperTrail::FooVersion' }
    ...
  end

1. Define the model-specific version class:

  # app/models/paper_trail/foo_version.rb
  module PaperTrail
    class FooVersion < PaperTrail::Version
      self.table_name = :foo_versions
    end
  end

1. Create the model-specific versions table:

  bundle exec rails generate migration add_foo_versions

  # db/migrate/timestamp_add_foo_versions.rb
  class AddFooVersions < ActiveRecord::Migration[5.2]
    def change
      create_table :foo_versions do |t|
        t.string   :item_type, null: false
        t.uuid     :item_id,   null: false
        t.string   :event,     null: false
        t.string   :whodunnit
        t.jsonb    :object
        t.jsonb    :object_changes
        t.datetime :created_at
      end

      add_index :foo_versions, %i[item_type item_id]
    end
  end

N.B: If the model being versioned uses a different type of primary key (i.e. integer instead of UUID), feel free to change the t.uuid to t.#{another_type}

References

• Exchange PR with initial implementation: https://github.com/artsy/exchange/pull/314
• PaperTrail docs on Custom Version Classes: https://github.com/paper-trail-gem/paper_trail/tree/091612fb565c5fa71aee828fa575cc4e4c180f28#6a-custom-version-classes

Analytics Notification

If you changed something in the /models make sure to inform #data (analytics) team about it in case it impacts their reports.

Did You Change GraphQL Schema?

Metaphysics is the current consumer of Exchange GraphQL schema and keeps a copy of latest schema in https://github.com/artsy/metaphysics/tree/master/src/data, if you have changed Exchange GraphQL schema, make sure you also update the copy of this schema in Metaphysics. In order to do so follow these steps:

1. In exchange run

rake graphql:schema:idl

2. rename schema.graphql file generated ☝🏼 to exchange.graphql

mv schema.graphql exchange.graphql

3. copy file above to your local update Metaphysics under src/data and make a PR to Metaphysics with this change.

There is a guide on how to add exchange operations to Metaphysics here

Talking to Exchange 🤑

In order to talk to Exchange GraphQL endpoint:

• Copy .env.example to .env
• Update the REPLACE_ME values in the .env file. You can reference the values used on staging with hokusai staging env get.
• Install dotenv by gem install dotenv
• Start local server dotenv rails s
• If you work at Artsy, get proper Gravity User Token following these instructions (the client application name is "Exchange Staging").
• Install and run GraphiQL app brew cask install graphiql
• In GraphiQL app, go to http://localhost:3000/api/graphql, you should ge unauthorized error
• Edit HTTP Headers and add Authorization header and set it to Bearer <token> where <token> is your Gravity token generated few steps above.

Working at Artsy?

GraphQL Queries

We share our GraphQL sample queries using Insomnia shared workspace. You can import latest queries from environments_and_requests.json

Get Access To Exchange

Access to Exchange Admin is limited to users with the role "Sales Admin". Ask someone with Role Manager permissions to grant your user "Sales Admin" permissions.

Debugging

Something went wrong? Ideally in the JSON response returned from Exchange there will be enough info to describe what went wrong. In case that was not useful, you can:

1. Check Sentry (password in 1Pass) and look for Exchange (staging or production) and see the error.
2. Follow exchange logs by doing

hokusai staging logs -f

If you think there is something we could improve in this error case, feel free to open an issue with details about what you did and what went wrong.