Getting PDF from WickedPDF for attachment via Carrierwave

问题

In Rails3, I am using the WickedPDF gem to render a PDF format of one of my models. This is working fine: /invoices/123 returns HTML, /invoices/123.pdf downloads a PDF.

In my Invoice model, I am using the state_machine gem to keep track of Invoice status. When an invoice goes from "unbilled" to "billed" state, I would like to grab a copy of the invoice PDF and attach it to the invoice model using CarrierWave.

I have the three parts working separately: the controller creates a PDF view, the model tracks state and triggers a callback when making the correct transition, and CarrierWave is set up properly. However, I'm having a heck of a time getting them to play nicely together.

If I just wanted to grab the HTML version of the invoice, I could call render_to_string from the model. But render_to_string seems to choke on receiving a PDF binary file. If I can get a stream of data back, it's pretty easy to write that data to a tempfile and attach it to the uploader, but I can't figure out how to get the data stream.

Any thoughts? Code below:

Invoice controller

def show
  @invoice = @agg_class.find(params[:id])

  respond_to do |format|
    format.pdf do
      render_pdf
    end
    format.html # show.html.erb
    format.json { render json: @aggregation }
  end
end

...

def render_pdf(options = {})
  options[:pdf] = pdf_filename
  options[:layout] = 'pdf.html'
  options[:page_size] = 'Letter'
  options[:wkhtmltopdf] = '/usr/local/bin/wkhtmltopdf'
  options[:margin] = {
    :top      => '0.5in',
    :bottom   => '1in',
    :left     => '0in',
    :right    => '0in'
  }
  options[:footer] = {
    :html => {
      :template   => 'aggregations/footer.pdf.haml',
      :layout     => false,
    }
  }
  options[:header] = {
    :html => {
      :template   => 'aggregations/header.pdf.haml',
      :layout     => false,
    }
  }
  render options
end

Invoice.rb

def create_pdf_copy

   # This does not work.    
   pdf_file = ApplicationController.new.render_to_string(
    :action => 'aggregations/show',
    :format => :pdf,
    :locals => { 
      :invoice => self
    }
  )

  # This part works fine if the above works.
  unless pdf_file.blank?
    self.uploads.clear
    self.uploads.create(:fileinfo => File.new(pdf_file), :job_id => self.job.id)
  end

end

UPDATE Found a solution.

def create_pdf_copy

    wicked = WickedPdf.new

    # Make a PDF in memory
    pdf_file = wicked.pdf_from_string( 
        ActionController::Base.new().render_to_string(
            :template   => 'aggregations/show.pdf.haml', 
            :layout     => 'layouts/pdf.html.haml',
            :locals     => { 
                :aggregation => self
            } 
        ),
        :pdf => "#{self.type}-#{self}",
        :layout => 'pdf.html',
        :page_size => 'Letter',
        :wkhtmltopdf => '/usr/local/bin/wkhtmltopdf',
        :margin => {
            :top      => '0.5in',
            :bottom   => '1in',
            :left     => '0in',
            :right    => '0in'
        },
        :footer => {
            :content => ActionController::Base.new().render_to_string({
                :template => 'aggregations/footer.pdf.haml', 
                :layout => false
            })
        },
        :header => {
            :content => ActionController::Base.new().render_to_string({
                :template => 'aggregations/header.pdf.haml', 
                :layout => false
            })
        }
    )

    # Write it to tempfile
    tempfile = Tempfile.new(['invoice', '.pdf'], Rails.root.join('tmp'))
    tempfile.binmode
    tempfile.write pdf_file
    tempfile.close

    # Attach that tempfile to the invoice
    unless pdf_file.blank?
        self.uploads.clear
        self.uploads.create(:fileinfo => File.open(tempfile.path), :job_id => self.job.id)
        tempfile.unlink
    end

end

回答1:

Solution:

def create_pdf_copy

    wicked = WickedPdf.new

    # Make a PDF in memory
    pdf_file = wicked.pdf_from_string( 
        ActionController::Base.new().render_to_string(
            :template   => 'aggregations/show.pdf.haml', 
            :layout     => 'layouts/pdf.html.haml',
            :locals     => { 
                :aggregation => self
            } 
        ),
        :pdf => "#{self.type}-#{self}",
        :layout => 'pdf.html',
        :page_size => 'Letter',
        :wkhtmltopdf => '/usr/local/bin/wkhtmltopdf',
        :margin => {
            :top      => '0.5in',
            :bottom   => '1in',
            :left     => '0in',
            :right    => '0in'
        },
        :footer => {
            :content => ActionController::Base.new().render_to_string({
                :template => 'aggregations/footer.pdf.haml', 
                :layout => false
            })
        },
        :header => {
            :content => ActionController::Base.new().render_to_string({
                :template => 'aggregations/header.pdf.haml', 
                :layout => false
            })
        }
    )

    # Write it to tempfile
    tempfile = Tempfile.new(['invoice', '.pdf'], Rails.root.join('tmp'))
    tempfile.binmode
    tempfile.write pdf_file
    tempfile.close

    # Attach that tempfile to the invoice
    unless pdf_file.blank?
        self.uploads.clear
        self.uploads.create(:fileinfo => File.open(tempfile.path), :job_id => self.job.id)
        tempfile.unlink
    end

end

回答2:

There's a better way: PDF in Rails without controllers.

来源：https://stackoverflow.com/questions/14743447/getting-pdf-from-wickedpdf-for-attachment-via-carrierwave