view :editor do |args|
  form.text_field :content, :class=>'card-content'
end

event :validate_number, :after=>:approve do
  errors.add :content, "'#{content}' is not numeric" unless valid_number?( content )
end

def valid_number?( string )
  valid = true
  begin
    Kernel.Float( string )
  rescue ArgumentError, TypeError
    valid = false
  end
  valid
end