Fortnox API

Wrapper gem for Fortnox AB's version 3 REST(ish) API. If you need to integrate an existing or new Ruby or Rails app against Fortnox this gem will save you a lot of time, you are welcome. Feel free to repay the community with some nice PRs of your own 😃

Status for master

Status for development

The rough status of this project is as follows (as of spring 2023):

• master branch and the released versions should be production ready.
• We are actively working on our generalization of this gem: rest_easy gem. It will be a base for REST API's in general.
• Basic structure complete. Things like getting customers and invoices, updating and saving etc.
• Some advanced features implemented, for instance support for multiple Fortnox accounts and filtering entities.
• We have ideas for more advanced features, like sorting entities, pagination of results but it's not implemented...
• A few models implemented. Right now we pretty good support for Customer, Invoice, Order, Article, Label and Project. Adding more models in general is quick and easy (that's the whole point with this gem), see the developer guide further down.

Architecture overview

The gem is structured with distinct models for the tasks of data, JSON mapping and saving state. These are called: model, type, mapper and repository.

If you come from a Rails background and have not been exposed to other ways of structuring the solution to the CRUD problem this might seem strange to you since ActiveRecord merges these roles into the ActiveRecord::Base class.

To keep it simple: The active record pattern (as implemented by Rails) is easier to work with if you only have one data source, the database, in your application. The data mapper pattern is easier to work with if you have several data sources, such as different databases, external APIs and flat files on disk etc, in your application. It's also easier to compose the data mapper components into active record like classes than to separate active records parts to get a data mapper style structure.

If you are interested in a more detailed description of the difference between the two architectures you can read this post that explains it well using simple examples: What’s the difference between Active Record and Data Mapper?

Model

The model role classes serve as dumb data objects. They do have some logic to coheres values etc, but they do not contain validation logic nor any business logic at all.

Attribute

Several of the models share attributes. One example is account, as in a Bookkeeping account number. These attributes have the same definition, cohesion and validation logic so it makes sense to extract them from the models and put them in separate classes. For more information, see Types below.

Immutability

The model instances are immutable. That means:

customer.name # => "Old Name"
customer.name = 'New Name' # => "New Name"

customer.name == "New Name" # => false

Normally you would expect an assignment to mutate the instance and update the name field. Immutability explicitly means that you can't mutate state this way, any operation that attempts to update state needs to return a new instance with the updated state while leaving the old instance alone.

So you might think you should do this instead:

customer = customer.name = 'New Name' # => "New Name"

But if you are familiar with chaining assignments in Ruby you will see that this does not work. The result of any assignment, LHS = RHS, operation in Ruby is RHS. Even if you implement your own = method and explicitly return something else. This is a feature of the language and not something we can get around. So instead you have to do:

customer.name # => "Old Name"
updated_customer = customer.update( name: 'New Name' ) # => <Fortnox::API::Model::Customer:0x007fdf22949298 ... >
updated_customer.name == "New Name" # => true

And note that:

customer.name # => "Old Name"
customer.update( name: 'New Name' ) # => <Fortnox::API::Model::Customer:0x007fdf21100b00 ... >
customer.name == "New Name" # => false

This is how all the models work, they are all immutable.

Exceptions

Models can throw Fortnox::API::AttributeError if an attribute is invalid in some way (for instance if you try to assign a too long string to a limited string attribute) and Fortnox::API::MissingAttributeError if a required attribute is missing.

Type

The types automatically enforce the constraints on values, lengths and, in some cases, content of the model attributes. Types forces your models to be correct before sending data to the API, which saves you a lot of API calls and rescuing the exception we throw when we get a 4xx/5xx response from the server (you can still get errors from the server; our implementation is not perfect. Also, Fortnox sometimes requires a specific combination of attributes).

Repositories

Used to load, update, create and delete model instances. These are what is actually wrapping the HTTP REST API requests against Fortnox's server.

Exceptions

Repositories can throw Fortnox::API::RemoteServerError if something went wrong at Fortnox.

Mappers

These are responsible for the mapping between our plain old Ruby object models and Fortnox JSON requests. The repositories use the mappers to map models to JSON requests and JSON to model instances when working with the Fortnox API, you will not need to use them directly.

Requirements

This gem is built for Ruby 2.6 or higher (see Travis configuration file for what versions we are testing against).

Installation

Add this line to your application's Gemfile:

gem 'fortnox-api'

And then execute:

$ bundle

Or install it yourself as:

$ gem install fortnox-api

Usage

Authorization

⚠️ Before 2022, Fortnox used a client ID and a fixed access token for authorization. This way of is now deprecated. The old access tokens have a life span of 10 years according to Fortnox. They can still be used, but you can't issue any new long lived tokens and they recommend to migrate to the new authorization process. This gem will no longer support the old way of authorization since v0.9.0.

You need to have a Fortnox app and to create such an app, you need to register as a Fortnox developer. It might feel as if "I just want to create an integration to Fortnox, not build a public app to in the marketplace". Yeah, we agree... You don't need to release the app on the Fortnox Marketplace, but you need that Fortnox app. Also, see further Fortnox app requirements down below.

Start your journey at Fortnox getting started guide. Note that there's a script to authorize the Fortnox app to your Fortnox account bundled with this gem to help you getting started, see Initialization. Also read Authorizing your integration.

Things you need:

• A Fortnox developer account
• A Fortnox app with:
  • Service account setting enabled (it's used in server to server integrations, which this is)
  • Correct scopes set
  • A redirect URL (just use a dummy URL if you want to, you just need the parameters send to that URL)
• A Fortnox test environment so that you can test your integration.

When you have authorized your integration you get an access token from Fortnox. It's a JWT with a expiration time (currently 1 hour). You also get a long lived refresh token (currently lasts for 31 days ). When you need a new access token you send a renewal request to Fortnox. That request contains the new access token as well as a new refresh token and some other data. Note that the old refresh token is invalidated when new tokens are requested. As long as you have a valid refresh token you will be available to request new tokens.

The gem exposes a specific repository for renewing tokens. You use it like this:

require 'fortnox/api'

tokens = Fortnox::API::Repository::Authentication.new.renew_tokens(
  refresh_token: 'a valid refresh token',
  client_id: "the integration's client id",
  client_secret: "the integration's client secret"
)

# You probably want to persist your tokens somehow...
store_refresh_token(tokens[:refresh_token])
store_access_token(tokens[:access_token])

# Set the new access token
Fortnox::API.access_token = tokens[:access_token]

# The gem will now use the new access token
Fortnox::API::Repository::Customer.new.all

It's up to you to provide a valid token to the gem and to renew it regularly, otherwise you need to start over again with the Initialization.

Get tokens

There's a script in bin/get_tokens to issue valid access and refresh tokens. Provide valid credentials in .env, see .env.template or have a look in the script itself to see what's needed.

Configuration

The gem can be configured in a configure block, where setting is one of the settings from the table below.

Fortnox::API.configure do |config|
  config.setting = 'value'
end

Setting	Description	Required	Default
base_url	The base url to Fortnox API	No	'https://api.fortnox.se/3/'
token_url	The url to Fortnox token endpoint	No	'https://apps.fortnox.se/oauth-v1/token'
debugging	For debugging	No	false
logger	The logger to use	No	A simple logger that writes to $stdout with log level WARN.

Support for multiple Fortnox accounts

Yes, we support working with several accounts at once. Simply switch access token between calls. The token is stored in the current thread, so it's thread safe.

repository = Fortnox::API::Repository::Customer.new

Fortnox::API.access_token = 'account1_access_token'
repository.all # Calls account1

Fortnox::API.access_token = 'account2_access_token'
repository.all # Calls account2

Automatic access tokens rotation (deprecated)

As of november 2021 and the new OAuth 2 flow, Fortnox has made adjustments to the rate limit and it is no longer calculated per access token (if you are not using the old auth flow, but that flow is deprecated in this gem since v0.9.0).

Usage

Repositories

Repositories are used to load,save and remove entities from the remote server. The calls are subject to network latency and are blocking. Do make sure to rescue appropriate network errors in your code.

require 'fortnox/api'

Fortnox::API.access_token = 'valid_access_token'

# Instanciate a repository
repo = Fortnox::API::Repository::Customer.new

# Get a list of all the entities
repo.all #=> <Fortnox::API::Collection:0x007fdf2104575638 @entities: [<Fortnox::API::Customer::Simple:0x007fdf21033ee8>, <Fortnox::API::Customer::Simple:0x007fdf22994310>, ... ]

# Get entity by id
repo.find( 5 ) #=> <Fortnox::API::Model::Customer:0x007fdf21100b00>

# Get entities by attribute
repo.find_by( customer_number: 5 ) #=> <Fortnox::API::Collection:0x007fdf22994310 @entities: [<Fortnox::API::Customer::Simple:0x007fdf22949298>]

If you are eagle eyed you might have spotted the different classes for the entities returned in a collection vs the one we get from find. The simple version of a class is used in thouse cases where the API-server doesn't return a full set of attributes for an entity. For customers the simple version has 10 attributes while the full have over 40.

Additional parameters

Note that find also supports a hash as an argument, which simply adds given hash keys as HTTP parameters to the call. This will let you search, sort, use limits and offsets as well as do pagination. See Fortnox documentation for more information about available parameters.

# Get second page of Customers
Fortnox::API::Repository::Customer.new.find { page: 2 }

Entities

All the repository methods return instances or collections of instances of some resource class such as customer, invoice, item, voucher and so on.

Instances are immutable and any update returns a new instance with the appropriate attributes changed (see the Immutable section under Architecture above for more details). To change the properties of a model works like this:

require 'fortnox/api'

customer #=> <Fortnox::API::Model::Customer:0x007fdf228db310>
customer.name #=> "Nelly Bloom"
customer.update( name: "Ned Stark" ) #=> <Fortnox::API::Model::Customer:0x0193a456ff0307>
customer.name #=> "Nelly Bloom"

updated_customer = customer.update( name: "Ned Stark" ) #=> <Fortnox::API::Model::Customer:0x0193a456fe3791>
updated_customer.name #=> "Ned Stark"

The update method takes an implicit hash of attributes to update, so you can update as many as you like in one go.

Contributing

See the CONTRIBUTE readme.