Lithic Ruby API library

The Lithic Ruby library provides convenient access to the Lithic REST API from any Ruby 3.2.0+ application. It ships with comprehensive types & docstrings in Yard, RBS, and RBI – see below for usage with Sorbet. The standard library's net/http is used as the HTTP transport, with connection pooling via the connection_pool gem.

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

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

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

gem "lithic", "~> 0.1.0.pre.alpha.32"

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)

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

Alternatively, you can use the #next_page? and #next_page methods for more granular control working with pages.

if page.next_page?
  new_page = page.next_page
  puts(new_page.data[0].product_id)
end

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::APIConnectionError => e
  puts("The server could not be reached")
  puts(e.cause)  # an underlying Exception, likely raised within `net/http`
rescue Lithic::Errors::RateLimitError => e
  puts("A 429 status code was received; we should back off a bit.")
rescue Lithic::Errors::APIStatusError => e
  puts("Another non-200-range status code was received")
  puts(e.status)
end

Error codes are as follows:

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})

By default, requests will time out after 60 seconds. 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})

On timeout, Lithic::Errors::APITimeoutError is raised.

Note that requests that time out are retried by default.

All parameter and response objects inherit from Lithic::Internal::Type::BaseModel, which provides several conveniences, including:

1. All fields, including unknown ones, are accessible with obj[:prop] syntax, and can be destructured with obj => {prop: prop} or pattern-matching syntax.

2. Structural equivalence for equality; if two API calls return the same values, comparing the responses with == will return true.

3. Both instances and the classes themselves can be pretty-printed.

4. Helpers such as #to_h, #deep_to_h, #to_json, and #to_yaml.

You can send undocumented parameters to any endpoint, and read undocumented response properties, like so:

Note: the extra_ parameters of the same name overrides the documented parameters.

page =
  lithic.cards.list(
    page_size: 10,
    request_options: {
      extra_query: {my_query_parameter: value},
      extra_body: {my_body_parameter: value},
      extra_headers: {"my-header": value}
    }
  )

puts(page[:my_undocumented_property])

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 request, as seen in the examples above.

To make requests to undocumented endpoints while retaining the benefit of auth, retries, and so on, you can make requests using client.request, like so:

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

The Lithic::Client instances are threadsafe, but are only are fork-safe when there are no in-flight HTTP requests.

Each instance of Lithic::Client has its own HTTP connection pool with a default size of 99. As such, we recommend instantiating the client once per application in most settings.

When all available connections from the pool are checked out, requests wait for a new connection to become available, with queue time counting towards the request timeout.

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

This library provides comprehensive RBI definitions, and has no dependency on sorbet-runtime.

You can provide typesafe request parameters like so:

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

Or, equivalently:

# Hashes work, but are not typesafe:
lithic.cards.create(type: "SINGLE_USE")

# You can also splat a full Params class:
params = Lithic::CardCreateParams.new(type: "SINGLE_USE")
lithic.cards.create(**params)

Since this library does not depend on sorbet-runtime, it cannot provide T::Enum instances. Instead, we provide "tagged symbols" instead, which is always a primitive at runtime:

# :ACTIVE
puts(Lithic::AccountUpdateParams::State::ACTIVE)

# Revealed type: `T.all(Lithic::AccountUpdateParams::State, Symbol)`
T.reveal_type(Lithic::AccountUpdateParams::State::ACTIVE)

Enum parameters have a "relaxed" type, so you can either pass in enum constants or their literal value:

# Using the enum constants preserves the tagged type information:
lithic.accounts.update(
  state: Lithic::AccountUpdateParams::State::ACTIVE,
  # …
)

# Literal values are also permissible:
lithic.accounts.update(
  state: :ACTIVE,
  # …
)

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.

Ruby 3.2.0 or higher.

See the contributing documentation.