Lithic Ruby API library

The Lithic Ruby library provides convenient access to the Lithic REST API from any Ruby 3.2.0+ application.

Documentation

Documentation for releases of this gem can be found on RubyDoc.

The REST API documentation can be found on docs.lithic.com.

Installation

To use this gem, install via Bundler by adding the following to your application’s Gemfile:

gem "lithic", "~> 0.1.0.pre.alpha.25"

Usage

require "bundler/setup"
require "lithic"

lithic = Lithic::Client.new(
  api_key: ENV["LITHIC_API_KEY"], # This is the default and can be omitted
  environment: "sandbox" # defaults to "production"
)

card = lithic.cards.create(type: "SINGLE_USE")

puts(card.token)

Sorbet

This library is written with Sorbet type definitions. However, there is no runtime dependency on the sorbet-runtime.

When using sorbet, it is recommended to use model classes as below. This provides stronger type checking and tooling integration.

lithic.cards.create(type: "SINGLE_USE")

Pagination

List methods in the Lithic API are paginated.

This library provides auto-paginating iterators with each list response, so you do not have to request successive pages manually:

page = lithic.cards.list

# Fetch single item from page.
card = page.data[0]
puts(card.product_id)

# Automatically fetches more pages as needed.
page.auto_paging_each do |card|
  puts(card.product_id)
end

Errors

When the library is unable to connect to the API, or if the API returns a non-success status code (i.e., 4xx or 5xx response), a subclass of Lithic::Errors::APIError will be thrown:

begin
  card = lithic.cards.create(type: "MERCHANT_LOCKED")
rescue Lithic::Errors::APIError => e
  puts(e.status) # 400
end

Error codes are as follows:

Cause	Error Type
HTTP 400	BadRequestError
HTTP 401	AuthenticationError
HTTP 403	PermissionDeniedError
HTTP 404	NotFoundError
HTTP 409	ConflictError
HTTP 422	UnprocessableEntityError
HTTP 429	RateLimitError
HTTP >= 500	InternalServerError
Other HTTP error	APIStatusError
Timeout	APITimeoutError
Network error	APIConnectionError

Retries

Certain errors will be automatically retried 2 times by default, with a short exponential backoff.

Connection errors (for example, due to a network connectivity problem), 408 Request Timeout, 409 Conflict, 429 Rate Limit, >=500 Internal errors, and timeouts will all be retried by default.

You can use the max_retries option to configure or disable this:

# Configure the default for all requests:
lithic = Lithic::Client.new(
  max_retries: 0 # default is 2
)

# Or, configure per-request:
lithic.cards.list(page_size: 10, request_options: {max_retries: 5})

Timeouts

By default, requests will time out after 60 seconds.

Timeouts are applied separately to the initial connection and the overall request time, so in some cases a request could wait 2*timeout seconds before it fails.

You can use the timeout option to configure or disable this:

# Configure the default for all requests:
lithic = Lithic::Client.new(
  timeout: nil # default is 60
)

# Or, configure per-request:
lithic.cards.list(page_size: 10, request_options: {timeout: 5})

Model DSL

This library uses a simple DSL to represent request parameters and response shapes in lib/lithic/models.

With the right editor plugins, you can ctrl-click on elements of the DSL to navigate around and explore the library.

In all places where a BaseModel type is specified, vanilla Ruby Hash can also be used. For example, the following are interchangeable as arguments:

# This has tooling readability, for auto-completion, static analysis, and goto definition with supported language services
params = Lithic::Models::CardCreateParams.new(type: "SINGLE_USE")

# This also works
params = {
  type: "SINGLE_USE"
}

Editor support

A combination of Shopify LSP and Solargraph is recommended for non-Sorbet users. The former is especially good at go to definition, while the latter has much better auto-completion support.

Advanced concepts

Making custom/undocumented requests

Undocumented request params

If you want to explicitly send an extra param, you can do so with the extra_query, extra_body, and extra_headers under the request_options: parameter when making a requests as seen in examples above.

Undocumented endpoints

To make requests to undocumented endpoints, you can make requests using client.request. Options on the client will be respected (such as retries) when making this request.

response = client.request(
  method: :post,
  path: '/undocumented/endpoint',
  query: {"dog": "woof"},
  headers: {"useful-header": "interesting-value"},
  body: {"he": "llo"},
)

Concurrency & connection pooling

The Lithic::Client instances are thread-safe, and should be re-used across multiple threads. By default, each Client have their own HTTP connection pool, with a maximum number of connections equal to thread count.

When the maximum number of connections has been checked out from the connection pool, the Client will wait for an in use connection to become available. The queue time for this mechanism is accounted for by the per-request timeout.

Unless otherwise specified, other classes in the SDK do not have locks protecting their underlying data structure.

Currently, Lithic::Client instances are only fork-safe if there are no in-flight HTTP requests.

Sorbet

Enums

Sorbet’s typed enums require sub-classing of the T::Enum class from the sorbet-runtime gem.

Since this library does not depend on sorbet-runtime, it uses a T.all intersection type with a ruby primitive type to construct a “tagged alias” instead.

module Lithic::AccountFinancialAccountType
  # This alias aids language service driven navigation.
  TaggedSymbol = T.type_alias { T.all(Symbol, Lithic::AccountFinancialAccountType) }
end

Argument passing trick

It is possible to pass a compatible model / parameter class to a method that expects keyword arguments by using the ** splat operator.

params = Lithic::Models::CardCreateParams.new(type: "SINGLE_USE")
lithic.cards.create(**params)

Versioning

This package follows SemVer conventions. As the library is in initial development and has a major version of 0, APIs may change at any time.

This package considers improvements to the (non-runtime) *.rbi and *.rbs type definitions to be non-breaking changes.

Requirements

Ruby 3.2.0 or higher.

Contributing

See the contributing documentation.