Class: Google4R::Checkout::CallbackHandler

Inherits:
Object
  • Object
show all
Defined in:
lib/google4r/checkout/merchant_calculation.rb

Overview

This class expects the message sent by Google. It parses the XMl document and returns the appropriate callback. If the callback sent by Google is invalid then a UnknownCallbackType is raised that you should catch and then send a 404 to Google to indicate that the callback handler has not been implemented yet.

See code.google.com/apis/checkout/developer/index.html#merchant_calculations_api for details.

Note that you must protect the HTTPS request to the piece of code using a CallbackHandler by HTTP Auth Basic. If you are using Ruby On Rails then you can use the great “simple_http_auth” plugin you can find here: blog.codahale.com/2006/05/11/basic-http-authentication-with-rails-simple_http_auth/

Usage Example

When you use a Rails controller to handle the calbacks by Google then your action to handle the callbacks could use a CallbackHandler as follows:

def google_checkout_api
  frontend = Google4R::Checkout::Frontend.new(FRONTEND_CONFIGURATION)
  frontend.tax_table_factory = TaxTableFactory.new
  handler = frontend.create_callback_handler

  begin
    callback = handler.handle(request.raw_post) # raw_post contains the XML
  rescue Google4R::Checkout::UnknownCallbackType => e
    # This can happen if Google adds new commands and Google4R has not been
    # upgraded yet. It is not fatal.
    render :text => 'ignoring unknown callback type', :status => 200
    return
  end

  # ...
end

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(frontend) ⇒ CallbackHandler

Create a new CallbackHandler and assign value of the parameter frontend to the frontend attribute.



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# File 'lib/google4r/checkout/merchant_calculation.rb', line 78

def initialize(frontend)
  @frontend = frontend
end

Instance Attribute Details

#frontend ⇒ Object

The Frontend object that created this CallbackHandler



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# File 'lib/google4r/checkout/merchant_calculation.rb', line 74

def frontend
  @frontend
end

Instance Method Details

#handle(xml_str) ⇒ Object

Parses the given xml_str and returns the appropriate *Callback class. At the moment, only MerchantCalculationCallback objects can be returned.



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# File 'lib/google4r/checkout/merchant_calculation.rb', line 84

def handle(xml_str)
  root = REXML::Document.new(xml_str).root
  
  case root.name
  when 'merchant-calculation-callback' then
    MerchantCalculationCallback.create_from_element(root, frontend)
  else
    raise UnknownCallbackType, "Unknown callback type: #{root.name}"
  end
end