Sarav's Weblog

Technical Articles for RoR Developers

Paypal on Rails – ActiveMerchant tips

Anyone who has looked into using ActiveMerchant and PayPal together knows it is quite a challenge. ActiveMerchant is great, but there is no documentation for using it with Paypal. Here are some tips to help you get it working:

Here is a page with some good references.

Setting up Paypal

The paypal website is a bit tough to navigate and they don’t make it obvious to figure out what are all the things you need to do to get it all setup.

  1. You will need a sandbox (developer) paypal account to test your set up. Sign up here
  2. The sandbox does not send emails, so you will have to use the Sandbox Email Tab to validate your sandbox account email address.
  3. Launch the sandbox
  4. Create a sandbox business account. and go through the normal paypal verification stuff. (It does not use your real bank account.)
  5. Go to the Merchant Services tab and signup for a Website Payments Pro Account.
  6. Verify your merchant account. You will be asked to enter you SSN number, use 111 + six random numbers. If you get an error message, try a different six numbers, the fake ssn must be unique in the sand box.
  7. Under the My Account tab and the Profile subtab and the Billing Agreements link, make sure you accept the Agreement.
  8. Same for the PayPal Monthly Billing link.
  9. Follow these instructions to create your API Certificate. Do not make the API Signature. You only need to do the “Step 1. Generate Certificate” part.
  10. Make sure you save the username & password given and download and save the pem file.

Paypal should now be set up. You will have to go through and do all the same stuff for your real paypal account, once your development is done and working.

Setting up ActiveMerchant

  1. Install ActiveMerchant by following the instructions, you will need to install the money gem, which ActiveMerchant requires.
  2. Rename the pem file to cert_key_pem_dev.txt and put it in your config dir.
  3. Add the following code to your environments/development.rb:
    config.after_initialize do
      ActiveMerchant::Billing::Base.gateway_mode = :test
      ActiveMerchant::Billing::PaypalGateway.pem_file = + '/config/cert_key_pem_dev.txt')
    $PAYPAL_LOGIN = ''
  5. Use the actual username and password in the previous code (don’t use the empty strings 🙂
  6. Do the same for the environments/test.rb
  7. Do the same for the environments/production.rb, except remove the line: ActiveMerchant::Billing::Base.gateway_mode = :test and use the cert_key_pem_prod.txt file (which you can get through your real paypal account (renaming to cert_key_pem_prod.txt ).
  8. Do something like this in your code:
    amount = 1000 #$10.00
    credit_card =
        :type       => 'visa',
        :number     => '4242424242424242',
        :month      => 8,
        :year       => 2009,
        :first_name => 'Bob',
        :last_name  => 'Bobsen',
        :verification_value=> '123'
    flash[:error] = credit_card.errors and return unless credit_card.valid?
    billing_address = {
        :name     => "John Smith",
        :address1 => '123 First St.',
        :address2 => '',
        :city     => 'Los Angeles',
        :state    => 'CA',
        :country  => 'US',
        :zip      => '90068',
        :phone    => '310-555-1234'
    gateway =>$PAYPAL_LOGIN, :password=>$PAYPAL_PASSWORD)
    res = gateway.authorize(amount, credit_card, :ip=>request.remote_ip, :billing_address=>billing_address)
    if res.success?
        gateway.capture(amount, res.authorization)
        flash[:notice] = "Authorized"
        redirect_to somewhere_url
        flash[:error] = "Failure: " + res.message.to_s
  10. Make sure State and Country are two character code.
  11. The credit card errors is actually a hash, not an array (like AR.errors), so you will need a helper to display the error.

Last Tip

  1. When testing with paypal, you must use port 80: ./script/server -p 80

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