client.erb

<%= link_to "Edit", @model.edit_path %>

edit_path.rb

module EditPath
  include Rails.application.routes.url_helpers
  include ActionController::Base.helpers
  def edit_path
    url_for controller: self.class.pluralize, action: 'edit'
  end
end

model.rb

class Model < ActiveRecord::Base
  include EditPath
end