Rails/Prawn: how do I use rails helpers inside a Prawn class?

Question

I'm trying to use rails 3.2 helpers inside a prawn class, but rails throws:

undefined method `number_with_precision' for #<QuotePdf:0x83d4188>

Prawn Class

class QuotePdf < Prawn::Document
  def initialize(quote)
    super()

    text "sum: #{number_with_precision(quote.sum)}"
  end
end

Controller

def show
  @quote = current_user.company.quotes.where(:id => params[:id]).first
  head :unauthorized and return unless @quote

  respond_with @quote, :layout => !params[:_pjax] do |format|
    format.pdf do
      send_data QuotePdf.new(@quote).render, filename: "Devis-#{@quote.date_emission.strftime("%d/%m/%Y")}.pdf",
      type: "application/pdf"
    end
  end
end

Thanks for your help.

Answer 1

Just pass the view_context to the Prawn sub-class initializer.

def initialize(quote, view_context)
  super()
  @view = view_context
end

in Controller, change to:

QuotePdf.new(@quote, view_context)

then in Prawn sub-class, this will work:

@view.number_with_precision(quote.sum)

Answer 2

If iafonov solution doesn't work, you may just have to include NumberHelper without the prefix.