CSVRb-Rails — Streaming CSVs with ActionView templates

In your Gemfile:

gem 'csv'
gem 'csv_rb'

• >= Rails 5.2
  • Latest Version Tested With:
    • 5.2
    • 6.0
• >= Ruby 2.5
  • Latest Version Tested With:
    • 2.6
    • 2.7

CSVRb provides a renderer and a template handler. It adds the :csv format and parses .csv.csvrb templates. This lets you take all the csvrb code out of your controller or model and place it inside the template, where view code belongs! Strongly inspired by Axlsx-Rails

To use CSVRb set your instance variables in your controller and configure the response if needed:

class ButtonController < ApplicationController
  def action_name
    @buttons = Button.all
    respond_to do |format|
      format.csv
    end
  end
end

Create the template with the .csv.csvrb extension (action_name.csv.csvrb for example.) Watch out for typos! In the template, use csv_package variable to create your spreadsheet:

csv << ['Cell 1', 'Cell 2']

This is where you place all your csvrb specific markup. Add worksheets, fill content, merge cells, add styles. See the csvrb examples page to see what you can do.

Remember, like in erb templates, view helpers are available to use the .csv.csvrb template.

That's it. Call your action and your spreadsheet will be delivered.

You can call render in any of the following ways:

# rendered, no disposition/filename header
render 'buttons'
# rendered from another controller, no disposition/filename header
render 'featured/latest'
# template and filename of 'buttons'
render csv: 'buttons'
# template from another controller, filename of 'latest_buttons'
render csv: 'latest_buttons', template: 'featured/latest'

To specify a disposition (such as inline so the spreadsheet is opened inside the browser), use the disposition option:

render csv: "buttons", disposition: 'inline'

If render csv: is called, the disposition defaults to attachment.

If Rails calls csvrb through default channels (because you use format.csv {} for example) you must set the filename using the response header:

format.csv {
  response.headers['Content-Disposition'] = 'attachment; filename="my_new_filename.csv"'
}

If you use render csv: the gem will try to guess the file name based on the :csv key value

# filename of 'buttons.csv'
render csv: 'buttons'
# filename of 'latest_buttons.csv'
render csv: 'latest_buttons', template: 'featured/latest'

If that fails, pass the :filename parameter:

render csv: "action_or_template", filename: "my_new_filename.csv"

Partials work as expected, but you must pass in relevant spreadsheet variables:

csv << ['BEFORE']
render :partial => 'csv_partial', :locals => { csv: csv }
csv << ['AFTER']

With the partial simply using the passed variables:

# _csv_partial.csv.csvrb

csv << ['Partial Content']

To use an csv template to render a mail attachment, use the following syntax:

class UserMailer < ActionMailer::Base
  def export(users)
    csv = render_to_string layout: false, handlers: [:csvrb], formats: [:csv], template: "users/export", locals: {users: users}
    attachment = Base64.encode64(csv)
    attachments["Users.csv"] = {mime_type: Mime[:csv], content: attachment, encoding: 'base64'}
    # For rails 4 use Mime::CSV
    # attachments["Users.csv"] = {mime_type: Mime::CSV, content: attachment, encoding: 'base64'}
    # self.instance_variable_set(:@_lookup_context, nil) # If attachments are rendered as content, try this and open an issue
    ...
  end
end

• If the route specifies or suggests the :csv format you do not need to specify formats or handlers.
• If the template (users/export in this case) can refer to only one file (users/export.csv.csvrb), you do not need to specify handlers, provided the formats key includes :csv.
• Specifying the encoding as 'base64' can help avoid UTF-8 errors.

There is no built-in way to test your resulting sheets at this time

• Sampson Crowley

Many thanks to contributors:

• Noel Peden for creating axlsx

June 6th, 2019: 0.5.2 release

• Initial Release