If you are using model objects in migrations (e.g. for inserting data) you should make sure that the migration works even if that model class is removed. I discovered this when setting up a new development environment and running all migrations in an empty database.

Let’s say you have the following migration code:

class InsertCounties < ActiveRecord::Migration
def self.up
County.create :code => ’10′, :name => ‘Blekinge’
County.create :code => ’20′, :name => ‘Dalarna’
end
end

This assumes that the County model is available when the migration is run. If you checked out the most recent version of your code from svn it is possible that it doesn’t contain the County model and the migration will fail. To check if County is available before trying to use it we can use Ruby’s defined? like this:

Update: No we can’t. defined? always returns false inside an ActiveRecord migration for some reason (maybe the class isn’t loaded before the actual call?). We have to use a begin…rescue…end block instead:

class InsertCounties < ActiveRecord::Migration
def self.up
begin
County.create :code => ’10′, :name => ‘Blekinge’
County.create :code => ’20′, :name => ‘Dalarna’
rescue
puts “Could not add data…”
end
end
end

This way the rest of the migrations will run.

Googling for information on how to use PDF::Writer shows that there are many european developers frustrated with the lack of UTF-8 support in PDF::Writer. As Ruby on Rails works great with UTF-8 these days this can be a bit of an issue.

Part of the problem lies in the fact that the PDF specification (at least up to 1.6) does not support UTF-8 (you can use UTF-16 if you like). I had the misfortune of plowing thorugh it a couple of years ago when developing a PDF form filler library for a customer (don’t ask).

In Ruby on Rails, this is easy to solve as long as you only use Latin characters with diacritics. The solution is to switch encoding back to ISO-8859-15 for text strings you feed to PDF::Writer.

A simple extension to the String class will do the trick:

class String
  require 'iconv'
  def to_iso
    c = Iconv.new('ISO-8859-15','UTF-8')
    c.iconv(self)
  end
end

If you are working in Rails you can put this code in the lib folder (I usually call the file string_extensions.rb).

Then, when you call the text method on your PDF::Writer intance you can easily pass a correctly encoded string.

Overriding PDF::Writer text method

A much cleaner approach, as Aníbal describes in the comment below, is to override PDF::Writer’s text method.

Put the following code in a file called pdfwriter_extensions.rb (or whatever you choose to call it) in your lib directory:

CONVERTER = Iconv.new( 'ISO-8859-15//IGNORE//TRANSLIT', 'utf-8')

module PDF
	class Writer
		alias_method :old_text, :text

		def text(textto, options = {})
			old_text(CONVERTER.iconv(textto), options)
		end

	end
end

In your controller that handles the PDF output you add:

  require 'pdf/writer'
  require 'pdfwriter_extensions'

…after which you can use PDF::Writer like in the tutorial:

    pdf = PDF::Writer.new
    pdf.select_font "Helvetica", :encoding => nil
    pdf.text "User name: <b>#{@user.name}</b>", :font_size => 16, :justification => :left
    send_data pdf.render, :disposition => 'inline', :filename => "user_details.pdf", :type => "application/pdf"