Rails 3 ActionMailer and Wicked_PDF

Question

I'm trying to generate emails with rendered PDF attachements using ActionMailer and wicked_pdf.

On my site, I'm using already both wicked_pdf and actionmailer separately. I can use wicked_pdf to serve up a pdf in the web app, and can use ActionMailer to send mail, but I'm having trouble attaching rendered pdf content to an ActionMailer (edited for content):

class UserMailer < ActionMailer::Base
  default :from => "webadmin@mydomain.com"

  def generate_pdf(invoice)
    render :pdf => "test.pdf",
     :template => 'invoices/show.pdf.erb',
     :layout => 'pdf.html'
  end

  def email_invoice(invoice)
    @invoice = invoice
    attachments["invoice.pdf"] = {:mime_type => 'application/pdf',
                                  :encoding => 'Base64',
                                  :content => generate_pdf(@invoice)}
    mail :subject => "Your Invoice", :to => invoice.customer.email
  end
end

Using Railscasts 206 (Action Mailer in Rails 3) as a guide, I can send email with my desired rich content, only if I don't try to add my rendered attachment.

If I try to add the attachment (as shown above), I get an attachement of what looks to be the right size, only the name of the attachment doesn't come across as expected, nor is it readable as a pdf. In addition to that, the content of my email is missing...

Does anyone have any experience using ActionMailer while rendering the PDF on the fly in Rails 3.0?

Thanks in advance! --Dan