Module: CopyCsv::ClassMethods

Defined in:
lib/copy_csv.rb

Instance Method Summary collapse

Instance Method Details

#copy_csv(io, relation: all) ⇒ Object

Performs a database query to copy results as CSV to an IO object.

CSV is created directly in PostgreSQL with less overhead then written to the provided IO object.

Example

File.open("users.csv", "wb") do |file|
  User.where(unsubscribed: false).copy_csv(io: file)
end

Returns nil



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# File 'lib/copy_csv.rb', line 19

def copy_csv(io, relation: all)
  query = "    COPY (\#{ relation.to_sql }) TO STDOUT WITH DELIMITER ',' CSV HEADER ENCODING 'UTF-8' QUOTE '\"'\n  SQL\n\n  raw = connection.raw_connection\n  raw.copy_data(query) do\n    while (row = raw.get_copy_data)\n      io.puts row\n    end\n  end\n\n  nil\nend\n"