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Ruby on Rails phone number validation

Tuesday, 20 January, 2009 — software rails testing

I recently launched a Rails application that has a phone number field available to it. In the process of writing my spec tests, I allowed the phone field to be a certain number of characters and allowed it to be empty. The formatting test, however, I left pending. I searched for, but did not find a great solution past some very unreadable regular expressions.

In the course of watching a movie this evening, I had a solution. I created an array of acceptable formats, looped over the array and checked each entry against the phone number. If I had a match, the validation passes. Setting the string match to the beginning and I can allow for extensions without being too persnickety about formatting.

Here it is (via a handy gist):

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def valid_phone
  return true if phone.blank?

  phone_formats = [
    /^\(\d\d\d\) \d\d\d-\d\d\d\d/,
    /^\d\d\d\.\d\d\d\.\d\d\d\d/,
    /^\d\d\d\-\d\d\d\-\d\d\d\d/
  ]

  valid = false
  phone_formats.each do |format|
    if phone.match( format )
      valid = true
    end
  end

  unless valid
    errors.add("Phone format isn't recognized")
  end
end

Here are some spec test examples.

It doesn’t handle international formats, but, for right now, it fits my needs.