Calling Deepl's API from the Crystal language

As the title suggests, recently, ChatGPT is becoming popular. However, ChatGPT is more accurate in responding when asked in English rather than in Japanese. Therefore, there are times when you want to quickly translate from Japanese to English to ask questions to ChatGPT.

Snippet to call DeepL translation from Crystsal language

By giving reference code and reference documents to ChatGPT from Crystal language, a language to call DeepL's API was written. An API Key is required for use.

require "http/client"
require "json"

module Deepl
  class ApiKeyError < Exception; end
  class RequestError < Exception; end

  class Translator
    API_ENDPOINT = "https://api-free.deepl.com/v2/translate"

    @http_headers : HTTP::Headers

    def initialize
      @http_headers = build_http_headers
    end

    def build_http_headers
      HTTP::Headers{
        "Authorization" => "DeepL-Auth-Key #{get_api_key}",
        "Content-Type"  => "application/x-www-form-urlencoded",
      }
    end

    def get_api_key
      if ENV.has_key?("DEEPL_API_KEY")
        ENV["DEEPL_API_KEY"]
      else
        raise ApiKeyError.new
      end
    end

    def request_translation(text : String, target_lang : String)
      request_payload = "text=#{URI.encode_www_form(text)}&target_lang=#{URI.encode_www_form(target_lang)}"
      send_post_request(request_payload)
    end

    def send_post_request(request_data : String)
      HTTP::Client.post(API_ENDPOINT, body: request_data, headers: @http_headers)
    rescue error
      raise RequestError.new("Error: #{error} #{error.message}")
    end

    def translate(text, target_lang)
      response = request_translation(text, target_lang)
      parsed_response = JSON.parse(response.body)
      parsed_response.dig("translations", 0, "text")
    end
  end
end

The Example Response looks like this:

{
  "translations": [
    {
      "detected_source_language": "EN",
      "text": "Hallo, Welt!"
    }
  ]
}

You can use it like this:

input_text = ARGV[0]
target_lang = "ZH"

translator = Deepl::Translator.new
translated_text = translator.translate(input_text, target_lang)

puts translated_text

./deepl Hello.
你好。

That's all. Have a nice day.