gem 'parqueteur', '~> 1.0'

gem 'parqueteur', '~> 1.0', require: false

require 'parqueteur'

class FooParquetConverter < Parqueteur::Converter
  column :id, :bigint
  column :reference, :string
  column :datetime, :timestamp
end

data = [
  { 'id' => 1, 'reference' => 'hello world 1', 'datetime' => Time.now },
  { 'id' => 2, 'reference' => 'hello world 2', 'datetime' => Time.now },
  { 'id' => 3, 'reference' => 'hello world 3', 'datetime' => Time.now }
]

# initialize Converter with Parquet GZIP compression mode
converter = FooParquetConverter.new(data, compression: :gzip)

# write result to file
converter.write('hello_world.parquet')

# in-memory result (StringIO)
converter.to_io

# write to temporary file (Tempfile)
# don't forget to `close` / `unlink` it after usage
converter.to_tmpfile

# convert to Arrow::Table
pp converter.to_arrow_table

require 'parqueteur'

class Car
  attr_reader :name, :production_year

  def initialize(name, production_year)
    @name = name
    @production_year = production_year
  end
end

class CarParquetConverter < Parqueteur::Converter
  column :name, :string
  column :production_year, :integer

  transform do |car|
    {
      'name' => car.name,
      'production_year' => car.production_year
    }
  end
end

cars = [
  Car.new('Alfa Romeo 75', 1985),
  Car.new('Alfa Romeo 33', 1983),
  Car.new('Audi A3', 1996),
  Car.new('Audi A4', 1994),
  Car.new('BMW 503', 1956),
  Car.new('BMW X5', 1999)
]

# initialize Converter with Parquet GZIP compression mode
converter = CarParquetConverter.new(data, compression: :gzip)

# write result to file
pp converter.to_arrow_table