attr-csv¶ ↑

This gem allows you to define CSV-style attributes for your ActiveRecord models. This is similar to serializing an ActiveRecord attribute except that it is stored in the database column as comma-separated-values rather than a JSON or YAML.

The advantage of using the CSV format in the database is that you can use the FIND_IN_SET() function (MySQL) to perform queries that can filter based on a particular value found in the set. If you don’t use MySQL, it can still be used as just another way to serialize an array into a database column. It sure prints better in a select result set.

If these reasons aren’t compelling enough for you, don’t use it.

Here is an example usage:

class MyCsvModel < ActiveRecord::Base
  attr_csv :multivalue
end

# The schema
CREATE TABLE my_csv_models (
  id INTEGER PRIMARY KEY,
  multivalue_csv VARCHAR(255)
)

# Use it
m = MyCsvModel.create! multivalue: [ 'a', 'b', 'c' ]

# Query for a value in the set...
ms = MyCsvModel.where "FIND_IN_SET('a', multivalue_csv) > 0"

ms.first.multivalue.inspect

# => [ 'a', 'b', 'c' ]

The default behavior is to assume that the database column will be named the same as the attribute with an appended ‘_csv’.

If the CSV attribute is set to an empty array (or nil), the database column will be set to nil.

You can actually use the ‘attr_csv’ function in a Plain Old Ruby Object, but I have yet to figure out the use for it (unless it was to be used with a different ORM - I’m not that adventurous).

• Check out the latest master to make sure the feature hasn’t been implemented or the bug hasn’t been fixed yet.

• Check out the issue tracker to make sure someone already hasn’t requested it and/or contributed it.

• Fork the project.

• Start a feature/bugfix branch.

• Commit and push until you are happy with your contribution.

• Make sure to add tests for it. This is important so I don’t break it in a future version unintentionally.

• Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.

Copyright © 2013 Dave. See LICENSE.txt for further details.