Transforming PostgreSQL arrays

transform_pg_array.rb

# monkey patch String class
# source: http://drawingablank.me/blog/ruby-boolean-typecasting.html
class String
  def to_bool
    return true if self == true || self =~ (/^(true|t|yes|y|1)$/i)
    return false if self == false || self.empty? || self =~ (/^(false|f|no|n|0)$/i)
    raise ArgumentError.new("invalid value for Boolean: \"#{self}\"")
  end
end

# Postgres returns an array as a string like "{true,false,true,true,false}"
# type: 'boolean' or 'integer'
def transform_pg_array(string, type)
  return [] if string.nil?

  array = string.split(',')

  if type == 'boolean'
    array.map! do |element| 
      element = /true|false/.match(element).to_s
      element.to_bool
    end
  elsif type == 'integer'
    array.map! do |element|
      element = /\d+/.match(element).to_s
      element.to_i
    end
  else
    raise ArgumentError, 'please specify a type to cast into: (boolean|integer)'
  end

  return array
end

Usage

transform_pg_array("{true,false,true,true,false}", 'boolean')
# => [true, false, true, true, false]