Writing Data

Writing to a CSV file follows a similar pattern to the CSV.foreach method we learned about previously, except that, here, we use the CSV.open method and supply a block.

Inside the block, we have access to the file, which we can write to by simply calling puts on the opened csv variable. In the same way as before, we do not need to manually call close as the block will automatically do that for us when it exits:

require 'csv'
CSV.open("new_users.csv", "w") do |csv|
  csv.puts ["Sarah Meyer", "25", "Cologne"]
  csv.puts ["Matt Hall", "35", "Sydney"]
end

There is an alternative syntax that you may see other people using that works in the same way and makes use of the append operator instead of the puts method. We do this by using the object << value syntax. Really, puts is just an alias for <<, so you can expect it to work in the same way:

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