Faraday MyRaiseError middleware

connection.rb

# A patch for faraday raise_error middleware for my usecase
# faraday: https://github.com/lostisland/faraday

class Connection
  def self.foo_service
    Thread.current[:foo_connection] ||= Faraday.new(Rails.application.config.x.foo_service_url) do |conn|
      conn.request :json
      conn.response :my_raise_error # See below comment
      conn.response :json, :content_type => /\bjson$/

      conn.adapter :net_http
    end
  end

  # Use our original MyRaiseError middleware which is basically same with Faraday::Response::RaiseError middleware
  # and Error classes, which is the subset of Faraday::Error family
  # See:
  # https://github.com/lostisland/faraday/blob/master/lib/faraday/response/raise_error.rb
  # https://github.com/lostisland/faraday/blob/master/lib/faraday/error.rb
  # https://github.com/lostisland/faraday/pull/1135
  class MyRaiseError < Faraday::Response::Middleware
    ClientErrorStatuses = (400...500).freeze
    ServerErrorStatuses = (500...600).freeze

    def on_complete(env)
      case env[:status]
      when ClientErrorStatuses
        raise ClientError.new(response: env.response)
      when ServerErrorStatuses
        raise ServerError.new(response: env.response)
      when nil
        raise Error.new(response: env.response)
      end
    end
  end

  Faraday::Response.register_middleware(my_raise_error: MyRaiseError)

  class Error < StandardError
    attr_reader :response, :wrapped_exception

    # @qsona: changed this signature from the original one
    # See: https://github.com/lostisland/faraday/pull/1135
    def initialize(exc = nil, response: nil)
      @wrapped_exception = nil unless defined?(@wrapped_exception)
      @response = response
      super(exc_and_msg!(exc))
    end

    def backtrace
      if @wrapped_exception
        @wrapped_exception.backtrace
      else
        super
      end
    end

    def inspect
      inner = +''
      inner << " wrapped=#{@wrapped_exception.inspect}" if @wrapped_exception
      inner << " response=#{@response.to_hash.inspect}" if @response
      inner << " #{super}" if inner.empty?
      %(#<#{self.class}#{inner}>)
    end

    protected

    # exc      - Either an Exception, or a string message.
    # @qsona: changed this signature from the original one
    def exc_and_msg!(exc)
      if @wrapped_exception.nil?
        @wrapped_exception, msg = exc_and_msg(exc)
        return msg
      end

      exc.to_s
    end

    # @qsona: changed this signature from the original one
    def exc_and_msg(exc)
      return [exc, exc.message] if exc.respond_to?(:backtrace)

      [nil, exc.to_s]
    end
  end

  # Faraday client error class. Represents 4xx status responses.
  class ClientError < Error
  end

  # Faraday server error class. Represents 5xx status responses.
  class ServerError < Error
  end
end