CSV.generate时，生成不带“”的空字段

Question

Ruby 2.2, Ruby on Rails 4.2

I'm genarating some CSV data in Ruby on Rails, and want empty fields to be empty, like ,, not like ,"", . I wrote codes like below:

somethings_cotroller.rb

def get_data
  respond_to do |format|
    format.html
    format.csv do
      @data = SheetRepository.accounts_data
      send_data render_to_string, type: :csv
    end
  end
end

somethings/get_data.csv.ruby

require 'csv'
csv_str = CSV.generate do |csv|
  csv << [1,260,37335,'','','','','','']
  ...
end

And this generates CSV file like this.

get_data.csv

1,260,37335,"","","","","",""

I want CSV data like below.

1,260,37335,,,,,,

It seems like Ruby adds "" automatically.

How can I do this??

Answer 1

In order to get CSV to output an empty column, you need to tell it that nothing is in the column. An empty string, in ruby, is still something, you'll need to replace those empty strings with nil in order to get the output you want:

csv_str = CSV.generate do |csv|
  csv << [1,260,37335,'','','','','',''].map do |col|
    col.respond_to?(:empty?) && col.empty? ? nil : col
  end
end
# => 1,260,37335,,,,,,

In rails you can clean that up by making use of presence , though this will blank out false as well:

csv_str = CSV.generate do |csv|
  csv << [1,260,37335,'',false, nil,'','',''].map(&:presence)
end
# => 1,260,37335,,,,,,

Answer 2

The CSV documentation shows an option that you can use for this case. There are not examples but you can guess what it does.

The only consideration is, you need to send an array of Strings, otherwise, you will get a NoMethodError

csv_str = CSV.generate(write_empty_value: nil) do |csv|
  csv << [1,260,37335,'','','','','','', false, ' ', nil].map(&:to_s)
end
=> "1,260,37335,,,,,,,false, ,\n"

The benefit of this solution is, you preserve the false .

Answer 3

I resolved by myself!

in somethings_controller.rb

send_data render_to_string.gsub("\"\"",""), type: :csv