Underscore Params

Forces all param keys in Rails to be underscored. eg

{'anObject' => 'value'} turns into {'an_object' => 'value'}

Will underscore all param keys including deeply nested ones.

Helpful if you do not have control over the view layer / what params are being sent to the application and don't want to complicate controllers / models with conversion logic.

Many javascript apps / scripts have the convention of their model attributes to be written using camelCase while ruby prefers the snake_case convention. This gem helps smooth out the inconsistency.

So instead of doing this in controllers:

params[:objectName] || params[:object_name]

it can be simply


regardless of what format the client sends


Add this line to your application's Gemfile:

gem 'underscore_params'

And then execute:

$ bundle

Or install it yourself as:

$ gem install underscore_params


  • Just reference in Gemfile
  • Works for Rails 4+ (not tested on earlier versions). YMMV.


  1. Fork it ( http://github.com/ansonK/underscore_params/fork )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request


Underscore Params is released under the MIT License.