Rails 3 ActionMailer and Wicked_PDF

I suspect the issue is you're defining the overall email as multipart/alternative, suggesting each part is just an alternate view of the same message.

I use something like the following to send mixed html/plain emails with attachments, and it seems to work OK.

class InvoiceMailer < ActionMailer::Base

  def invoice(invoice)
    from          CONFIG[:email]
    recipients    invoice.email
    subject       "Bevestiging Inschrijving #{invoice.course.name}"
    content_type  "multipart/mixed"

    part(:content_type => "multipart/alternative") do |p|
      p.part "text/html" do |p|
        p.body = render_message 'invoice_html', :invoice => invoice
      end

      p.part "text/plain" do |p|
        p.body = render_message 'invoice_plain', :invoice => invoice
      end
    end

    pdf = Prawn::Document.new(:page_size => 'A4')
    PDFRenderer.render_invoice(pdf, invoice)
    attachment :content_type => "application/pdf", :body => pdf.render, :filename => "factuur.pdf"

    invoice.course.course_files.each do |file|
      attachment :content_type => file.content_type, :body => File.read(file.full_path), :filename => file.filename
    end
  end

end

rename_column :table, :old_column, :new_column

You'll probably want to create a separate migration to do this. (Rename FixColumnName as you will.):

script/generate migration FixColumnName
# creates  db/migrate/xxxxxxxxxx_fix_column_name.rb

Then edit the migration to do your will:

# db/migrate/xxxxxxxxxx_fix_column_name.rb
class FixColumnName < ActiveRecord::Migration
  def self.up
    rename_column :table_name, :old_column, :new_column
  end

  def self.down
    # rename back if you need or do something else or do nothing
  end
end

For Rails 3.1 use:

While, the up and down methods still apply, Rails 3.1 receives a change method that "knows how to migrate your database and reverse it when the migration is rolled back without the need to write a separate down method".

See "Active Record Migrations" for more information.

rails g migration FixColumnName

class FixColumnName < ActiveRecord::Migration
  def change
    rename_column :table_name, :old_column, :new_column
  end
end

If you happen to have a whole bunch of columns to rename, or something that would have required repeating the table name over and over again:

rename_column :table_name, :old_column1, :new_column1
rename_column :table_name, :old_column2, :new_column2
...

You could use change_table to keep things a little neater:

class FixColumnNames < ActiveRecord::Migration
  def change
    change_table :table_name do |t|
      t.rename :old_column1, :new_column1
      t.rename :old_column2, :new_column2
      ...
    end
  end
end

Then just db:migrate as usual or however you go about your business.

For Rails 4:

While creating a Migration for renaming a column, Rails 4 generates a change method instead of up and down as mentioned in the above section. The generated change method is:

$ > rails g migration ChangeColumnName

which will create a migration file similar to:

class ChangeColumnName < ActiveRecord::Migration
  def change
    rename_column :table_name, :old_column, :new_column
  end
end