Csb

A simple and streaming support CSV template engine for Ruby on Rails.

Features

• Support for streaming downloads
• Output in UTF-8 with BOM
• Readable code
• High testability

Usage

Template handler

In app/controllers/reports_controller.rb:

def index
  @reports = Report.preload(:categories)
end

In app/views/reports/index.csv.csb:

csv.items = @reports

# When there are many records
# csv.items = @reports.find_each

# When there are many records with decorator
# csv.items = @reports.find_each.lazy.map(&:decorate)

# csv.filename = "reports_#{Time.current.to_i}.csv"
# csv.streaming = false
# csv.csv_options = { col_sep: "\t" }

csv.cols.add('Update date') { |r| l(r.updated_at.to_date) }
csv.cols.add('Categories') { |r| r.categories.pluck(:name).join(' ') }
csv.cols.add('Content', :content)
csv.cols.add('Empty')
csv.cols.add('Static', 'dummy')

Output:

Update date,Categories,Content,Empty,Static
2019/06/01,category1 category2,content1,,dummy
2019/06/02,category3,content2,,dummy

Directly

csv = Csb::Builder.new(items: items)
csv.cols.add('Update date') { |r| l(r.updated_at.to_date) }
csv.cols.add('Categories') { |r| r.categories.pluck(:name).join(' ') }
csv.cols.add('Content', :content)
csv.cols.add('Empty')
csv.cols.add('Static', 'dummy')
csv.build

# =>
# Update date,Categories,Content,Empty,Static
# 2019/06/01,category1 category2,content1,,dummy
# 2019/06/02,category3,content2,,dummy

Testing

# Your view
csv.items = @articles
csv.cols = Article.csb_cols

# Your Model
def self.csb_cols
  Csb::Cols.new do |cols|
    cols.add('Update date') { |r| I18n.l(r.updated_at.to_date) }
    cols.add('Categories') { |r| r.categories.pluck(:name).join(' ') }
    cols.add('Title', :title)
  end
end

# Your test
require 'csb/testing'

expect(Article.csb_cols.col_pairs(article)).to eq [
  ['Update date', '2020-01-01'],
  ['Categories', 'test rspec'],
  ['Title', 'Testing'],
]

expect(Article.csb_cols.as_table(articles)).to eq [
  ['Update date', 'Categories', 'Title'],
  ['2020-01-01', 'test rspec', 'Testing'],
  ['2020-02-01', 'rails gem', 'Rails 6.2'],
]

Installation

Add this line to your application's Gemfile:

gem 'csb'

And then execute:

$ bundle

Or install it yourself as:

$ gem install csb

Configuration

In config/initializers/csb.rb, you can configure the following values.

Csb.configure do |config|
  config.utf8_bom = true # default: false
  config.streaming = false # default: true
  config.csv_options = { col_sep: "\t" } # default: {}
  config.after_streaming_error = ->(error) do # default: nil
    Rails.logger.error(error)
    Bugsnag.notify(error)
  end
end

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/aki77/csb. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the Csb project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.