AsCSV

This gem allows you to expose CSV in your apps as you'd expose JSON or XML.

Rails is not strictly required, but currently the magic only works with rails 3.x.

Ruby 1.8 will work, but by default the order of the columns will not be guaranteed.

Installation

Add this line to your application's Gemfile:

gem 'as_csv'

Basic Usage

Simply add respond_to :csv in a controller

class WidgetsController < ApplicationController
  respond_to :xml, :json, :csv

  def index
    respond_with Widget.all
  end

  def show
    respond_with Widget.find(params[:id])
  end

end

Alternatively:

class WidgetsController < ApplicationController
  def index
    respond_to do |format|
      format.csv { render csv: Widget.all }
    end
  end

  def show
    respond_to do |format|
      format.csv { render csv: Widget.find(params[:id]) }
    end
  end
end

By default, you don't need to change your models at all.

class Widget < ActiveRecord::Base
  # attributes :code, :description, :name
end

> puts Widget.all.to_csv
id,name,description,code
1,widget-1,widget-description-1,1001
2,widget-2,widget-description-2,1002
3,widget-3,widget-description-3,1003
4,widget-4,widget-description-4,1004
 => nil

> puts Widget.where(code: [1001, 1002]).to_csv
id,name,description,code
1,widget-1,widget-description-1,1001
2,widget-2,widget-description-2,1002

> puts Widget.first.to_csv
id,name,description,code
1,widget-1,widget-description-1,1001
 => nil

Behind the scenes, any classes that include ActiveModel::Serialization will expose their attributes with to_csv.

Advanced Usage

Customizing the CSV

To change what's included in the CSV, define an as_csv method. This method must return a Hash.

class Widget < ActiveRecord::Base
  # attributes :code, :description, :name

  def as_csv(options={})
    attributes.slice('name', 'code')
  end

end

> puts Widget.all.to_csv
name,code
widget-1,1001
widget-2,1002
widget-3,1003
widget-4,1004
 => nil
>

You can also accept options:

class WidgetsController < ApplicationController
  respond_to :csv

  def index
    respond_with Widget.all, style: :short
  end
end

class Widget < ActiveRecord::Base
  attr_accessible :code, :description, :name

  def as_csv(options={})
    if options[:style] == :short
      attributes.slice('name', 'code')
    else
      attributes
    end
  end

end

Heterogenous Arrays

You can render any Array of objects that respond to as_csv.

class Foo < ActiveRecord::Base
  # attributes: name, description, code
end

class Bar < ActiveRecord::Base
  # attributes: name, description, barcode
end

> puts (Foo.all + Bar.all).to_csv
name,description,code,barcode
foo1,foo1-description,111,
foo2,foo2-description,222,
bar1,bar1-description,,acb12345
bar2,bar2-description,,xyz98765

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Ensure you've got development dependencies: (bundle)
4. Ensure existing tests run: (bundle exec rspec)
5. Make your changes, including new specs
6. Commit your changes (git commit -am 'Add some feature')
7. Push to the branch (git push origin my-new-feature)
8. Create new Pull Request