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.x.

Installation

Add this line to your application's Gemfile:

gem 'as_csv', '~> 3.0'

Basic Usage

Simply render CSV in a controller

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

Stdlib CSV options

If you need to pass any options to the underlying CSV library:

> puts (Foo.all + Bar.all).to_csv csv_options: {col_sep:'|'}
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