Class: CurrencySpy::Scraper

Inherits:
Object
  • Object
show all
Defined in:
lib/currency_spy/scraper.rb

Overview

A base class for all scrapers. Defines the common logic which is used across all of them.

Direct Known Subclasses

DnbNord, Nbp, Walutomat

Constant Summary collapse

RATE_DATA =

Each item has to be implemented as a method in the scraper sub class.

%w(buy_rate sell_rate medium_rate rate_time).freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Scraper

Base constructor



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# File 'lib/currency_spy/scraper.rb', line 20

def initialize()
  @url = nil
  @currency_code = 'EUR'
end

Instance Attribute Details

#available_codes ⇒ Object (readonly)

a list of codes available from given source



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# File 'lib/currency_spy/scraper.rb', line 15

def available_codes
  @available_codes
end

#currency_code ⇒ Object

current currency code we’re fetching rates for



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# File 'lib/currency_spy/scraper.rb', line 11

def currency_code
  @currency_code
end

#institution ⇒ Object (readonly)

name of the source institution



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# File 'lib/currency_spy/scraper.rb', line 17

def institution
  @institution
end

#url ⇒ Object

url of the source web page



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# File 'lib/currency_spy/scraper.rb', line 13

def url
  @url
end

Instance Method Details

#fetch_rates ⇒ Object

Method which calls all rate fetching methods from the sub class and returns a Hash with appropriate values.



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# File 'lib/currency_spy/scraper.rb', line 40

def fetch_rates
  if self.class.superclass.eql?(Object)
    raise Exception.new("This method should be invoked from CurrencySpy::Scraper sub class")
  else
    check_currency_code_validity
    response = {}
    RATE_DATA.each do |rate|
      symbol = rate.to_sym
      if self.class.instance_methods.include?(symbol)
        value = self.send(symbol)
        response[symbol] = value unless value.nil?
      end
    end
    return response
  end
end

#page(reload = false) ⇒ Object

Returns a Mechanize::Page instance which is the being searched on. If the page was once fetched it’s reuse. To reload, call with an argument evaluating to true.



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# File 'lib/currency_spy/scraper.rb', line 28

def page(reload = false)
  return nil if   url.nil?
  unless reload
    @page ||= Mechanize.new.get(url)
  else
    @page = Mechanize.new.get(url)
  end
  return @page
end