Rails before_validation strip whitespace best practices

Question

I would like my User model to sanitize some input before before save. For now some simple whitespace stripping will do. So to avoid people registering with "Harry " and pretend to be "Harry", for example.

I assume it is a good idea to do this stripping before validation, so that the validates_uniqueness_of can avoid accidental duplicates.

class User < ActiveRecord::Base
  has_many :open_ids

  validates_presence_of :name
  validates_presence_of :email
  validates_uniqueness_of :name
  validates_uniqueness_of :email
  validates_format_of :email, :with => /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\Z/i

  before_validation :strip_whitespace, :only => [:name, :email, :nick]

  private
  def strip_whitespace(value)
    value.responds_to?('strip') ? value.strip : value
  end
end

However, this code comes with an error ArgumentError: wrong number of arguments (0 for 1). I assumed the callback would be passed the values.

Also: is this stripping actually a good idea? Or should I rather validate on space and tell the user that "Harry " contains invalid spacess (I want to allow "Harry Potter" but not "Harry\s\sPotter").

Answer 1

Since I can't comment yet, I'll have to ask here: which method is giving the ArgumentError? strip, or responds_to?

Also, .split removes only leading and trailing whitespace. If you want "Harry Potter" with two spaces to not be accepted, you would either have to use a regex or, more simply, you could call .split, which removes spaces, and re-concatenate the string with a single space.

As far as if stripping is a good idea, I don't see a problem when it is just the leading/trailing whitespace. If there are multiple spaces in between words though, I would notify the user instead of automatically removing the extra spaces and giving the user a login that is not what they submitted.

Answer 2

I don't believe before_validation works like that. You probably want to write your method like this instead:

def strip_whitespace
  self.name = self.name.strip
  self.email = self.email.strip
  self.nick = self.nick.strip
end

You could make it more dynamic if you want using something like self.columns, but that's the gist of it.