ActionController::ParameterEncoding::ClassMethods
Methods
S
Instance Public methods
skip_parameter_encoding(action)

Specify that a given action's parameters should all be encoded as ASCII-8BIT (it “skips” the encoding default of UTF-8).

For example, a controller would use it like this:

class RepositoryController < ActionController::Base
  skip_parameter_encoding :show

  def show
    @repo = Repository.find_by_filesystem_path params[:file_path]

    # `repo_name` is guaranteed to be UTF-8, but was ASCII-8BIT, so
    # tag it as such
    @repo_name = params[:repo_name].force_encoding 'UTF-8'
  end

  def index
    @repositories = Repository.all
  end
end

The show action in the above controller would have all parameter values encoded as ASCII-8BIT. This is useful in the case where an application must handle data but encoding of the data is unknown, like file system data.

Source: show | on GitHub 

# File actionpack/lib/action_controller/metal/parameter_encoding.rb, line 44
def skip_parameter_encoding(action)
  @_parameter_encodings[action.to_s] = true
end