Setup varbinary columns or any other unsupported data type in rails migrations

varbinary_migration_columns_initializer.rb

# Provide varbinary columns in a Migration.
# Probably a better way to do this?
#
# Usage: 
#     => t.varbinary :column, :limit => 20, ....[options]
#

ActiveRecord::ConnectionAdapters::SchemaStatements.module_eval do
  def type_to_sql_with_varbinary(type, limit = nil, precision = nil, scale = nil)
    return type_to_sql_without_varbinary(type, limit, precision, scale) unless :varbinary == type.to_sym
    "varbinary(#{limit})"
  end
  alias_method_chain :type_to_sql, :varbinary
end
 
ActiveRecord::ConnectionAdapters::TableDefinition.class_eval do
  def varbinary(*args)
    options = args.extract_options!
    column_names = args
    type = :varbinary
    column_names.each { |name| column(name, type, options) }
  end
end

ActiveRecord::ConnectionAdapters::Table.class_eval do
  def varbinary(*args)
    options = args.extract_options!
    column_names = args
    type = :varbinary
    column_names.each do |name|
      column = ColumnDefinition.new(@base, name.to_s, type)
      if options[:limit]
        column.limit = options[:limit]
      elsif native[type].is_a?(Hash)
        column.limit = native[type][:limit]
      end
      column.precision = options[:precision]
      column.scale = options[:scale]
      column.default = options[:default] 
      column.null = options[:null]
      @base.add_column(@table_name, name, column.sql_type, options)
    end
  end 
end