CoinPrice

CoinPrice fetch cryptocurrency latest prices from a Source API and cache results into an in-memory hash or Redis. Price values are returned as BigDecimal and timestamps as Integer Unix time.

NOTE: Coinpaprika is currently set as the default price Source, but there are more sources available and CoinPrice is extensible by adding more Sources.

Install

Build and install the gem locally:

gem build coin_price.gemspec
gem install coin_price-2.1.7.gem

Or install it from rubygems.org in your terminal:

gem install coin_price

Or via Gemfile in your project:

source 'https://rubygems.org'

ruby '~> 2.5'

gem 'coin_price', '~> 2.1'

Require it in your Ruby code and CoinPrice module will be available:

require 'coin_price'

Configure

CoinPrice supports configuration with the .configure method.

# For example, setting up to use Redis instead of local in-memory hash
CoinPrice.configure do |config|
  config.redis_enabled = true
  config.redis_url = 'redis://localhost:6379/0'
end

List of configuration values:

• redis_enabled: whether or not to use Redis to cache values (defaults to false)
• redis_url: Redis URL to cache values if enabled (defaults to 'redis://localhost:6379/0')
• cache_key_prefix: custom prefix to be used in hash or Redis keys (defaults to an empty string)
• default_source: default Source to fetch prices from when none is specified (defaults to 'coinpaprika')

(See Config class at lib/coin_price/config.rb for the up-to-date list of configuration values)

NOTE: each Source may have its own configuration.

Usage

Get latest price

# Latest BTC price quoted in USD from Coinpaprika
CoinPrice.value('BTC', 'USD', 'coinpaprika')
# => 0.1122965353095e5

# Coinpaprika is currently set as the default source

CoinPrice.value('BTC', 'USD')
# => 0.1122965353095e5

CoinPrice.value('LTC', 'BTC')
# => 0.1056364e-1

Get many latest prices

# List many latest prices at once
CoinPrice.values(['BTC', 'ETH' , 'LTC', 'XRP'], ['USD', 'BTC', 'ETH'])
# => {
#   "BTC" => {
#     "USD" => 0.1122965353095e5,
#     "BTC" => 0.1e1,
#     "ETH" => 0.3849240929e2
#   },
#   "ETH" => {
#     "USD" => 0.29173683167e3,
#     "BTC" => 0.2600259e-1,
#     "ETH" => 0.1e1
#   },
#   "LTC" => {
#     "USD" => 0.11851911903e3,
#     "BTC" => 0.1056364e-1,
#     "ETH" => 0.40625353e0
#   },
#   "XRP" => {
#     "USD" => 0.3834478e0,
#     "BTC" => 0.3418e-4,
#     "ETH" => 0.131436e-2
#   }
# }

Cache

All fetched prices are stored into an in-memory hash or Redis and can be used instead of sending another request to the API:

CoinPrice.value('BTC', 'USD', 'coinpaprika', from_cache: true)
# => 0.1122965353095e5

CoinPrice.timestamp('BTC', 'USD', 'coinpaprika')
# => 1562352560

CoinPrice.values(['BTC', 'ETH', 'LTC', 'XRP'], ['USD', 'BTC', 'ETH'], 'coinpaprika', from_cache: true)
# Yields the same previous result for many latest prices

CoinPrice.timestamps(['BTC', 'ETH', 'LTC', 'XRP'], ['USD', 'BTC', 'ETH'], 'coinpaprika')
# Yields the same hash structure as the previous result for many latest prices,
# but with the timestamps instead of price values

# Number of requests performed today
CoinPrice.requests_count('coinpaprika')
# => 4

Keys and data

Cache keys of the in-memory hash or Redis follow the pattern:

• coin-price:{source}:value:{base}:{quote}
• coin-price:{source}:timestamp:{base}:{quote}

Example:

CoinPrice.cache.get('coin-price:coinpaprika:value:BTC:USD')
# => "0.1122965353095e5"
CoinPrice.cache.get('coin-price:coinpaprika:timestamp:BTC:USD')
# => "1562352560"

Or in Redis:

$ redis-cli
> get coin-price:coinpaprika:value:BTC:USD
> "0.1122965353095e5"
> get coin-price:coinpaprika:timestamp:BTC:USD
> "1562352560"

There is also a requests count at:

• coin-price:{source}:requests-count:{date}

Example:

CoinPrice.cache.get('coin-price:coinpaprika:requests-count:2019-07-05')
# => "4"

Or in Redis:

$ redis-cli
> get coin-price:coinpaprika:requests-count:2019-07-05
> "4"

Sources

You can get the up-to-date list of sources with:

CoinPrice.sources
# => {
#   "coinpaprika" => {
#     "name" => "Coinpaprika",
#     "website" => "https://coinpaprika.com/",
#     "notes" => "",
#     "class" => CoinPrice::Coinpaprika::Source
#   },
#   "coinmarketcap" => {
#     "name" => "CoinMarketCap",
#     "website" => "https://coinmarketcap.com/",
#     "notes" => "API Key is required",
#     "class" => CoinPrice::CoinMarketCap::Source
#   },
#   "ptax" => {
#     "name" => "PTAX",
#     "website" => "https://dadosabertos.bcb.gov.br/dataset/taxas-de-cambio-todos-os-boletins-diarios",
#     "notes" => "Brazil's Central Bank exchange rate for USD/BRL",
#     "class" => CoinPrice::PTAX::Source
#   },
#   "omnitrade" => {
#     "name" => "Omnitrade",
#     "website" => "https://omnitrade.io/",
#     "notes" => "",
#     "class" => CoinPrice::Omnitrade::Source
#   }
# }

Coinpaprika

• ID: 'coinpaprika'
• Name: Coinpaprika
• Website: https://coinpaprika.com

CoinPrice::Coinpaprika supports configuration with the .configure method.

List of configuration values:

• wait_between_requests: delay in seconds between retrying a request (defaults to 1)
• max_request_retries: number of retries before considering a request failed (defaults to 3)

(See Config class at lib/coin_price/coinpaprika/config.rb for Coinpaprika configuration values)

CoinMarketCap

• ID: 'coinmarketcap'
• Name: CoinMarketCap
• Website: https://coinmarketcap.com
• Notes: API Key is required

CoinPrice::CoinMarketCap supports configuration with the .configure method.

Set your CoinMarketCap API Key:

CoinPrice::CoinMarketCap.configure do |config|
  config.api_key = 'Your-CoinMarketCap-API-Key'
end

List of configuration values:

• api_key: your CoinMarketCap API Key (required; defaults to nil)
• listings_limit: number of results to return in the listings endpoint (defaults to 200 so it consumes only 1 call credit; max limit is 5000; see https://coinmarketcap.com/api/documentation/v1/#operation/getV1CryptocurrencyListingsLatest)
• wait_between_requests: delay in seconds between calls to the listings endpoint (defaults to 1)
• max_request_retries: number of retries before considering a request failed (defaults to 3)

(See Config class at lib/coin_price/coin_market_cap/config.rb for CoinMarketCap configuration values)

PTAX

• ID: 'ptax'
• Name: PTAX
• Website: https://dadosabertos.bcb.gov.br/dataset/taxas-de-cambio-todos-os-boletins-diarios
• Notes: Brazil's Central Bank exchange rate for USD/BRL

CoinPrice::PTAX supports configuration with the .configure method.

List of configuration values:

• wait_between_requests: delay in seconds between retrying a request (defaults to 1)
• max_request_retries: number of retries before considering a request failed (defaults to 3)

(See Config class at lib/coin_price/ptax/config.rb for PTAX configuration values)

Omnitrade

• ID: 'omnitrade'
• Name: Omnitrade
• Website: https://omnitrade.io

CoinPrice::Omnitrade supports configuration with the .configure method.

List of configuration values:

• wait_between_requests: delay in seconds between retrying a request (defaults to 1)
• max_request_retries: number of retries before considering a request failed (defaults to 3)

(See Config class at lib/coin_price/omnitrade/config.rb for Omnitrade configuration values)

Refresher

Refresher loops indefinitely and executes CoinPrice.values to populate the in-memory hash or Redis with the specified coin prices and source.

CoinPrice::Refresher.configure do |config|
  config.wait = 60 # seconds
end

CoinPrice::Refresher.call(['BTC', 'ETH', 'LTC', 'XRP'], ['USD', 'BTC', 'ETH'], 'coinpaprika')
# Awake! Refreshing prices...
# Done refreshing prices! Sleeping...

List of configuration values:

• wait: delay in seconds to wait until the next refresh (defaults to 120)
• wait_weekday_multiplier: multiplier to apply to wait on weekdays (Monday to Friday) (defaults to 1)
• wait_weekend_multiplier: multiplier to apply to wait on weekends (Saturday and Sunday) (defaults to 1)

How to add a new Source

• Create a new module at lib/coin_price/your_new_source and implement a Source < CoinPrice::Source class with the methods id and values:
  • id must return a unique string that identifies your Source in the code
  • values must receive the params bases, quotes which are arrays of currency symbols and return a hash with the price values for each base and quote pair
• Provide a test suite
• Add a group in the SimpleCov at spec/spec_helper.rb
• Register your new source class at lib/coin_price/available_sources.rb in the AVAILABLE_SOURCES constant
• Require it in lib/coin_price.rb

Optionally implement a Config class for you module and whichever class is needed for it to work.

(See CoinPrice::Coinpaprika module for an example)

Tests

Run tests with:

bundle exec rspec

Linter

Check your code style with:

bundle exec rubocop