Phone Number Form Validation

I have several forms where I want to save the phone numbers of users. In the actual database the field is a string and I would like to save in +160277688 format where 1 is country code, then area code then the number.

When I think about user inputs and enforce via my change set and form itself, I am debating how much logic goes into the change set versus closer to the form itself. Has anyone tackled phone numbers and wanted to save in a particular format?

Personally I feel there are a few ways to go about this depending on how needs to work with the data.

  • Only used by real people: Store the number as supplied as string.
  • Used by people, but format enforced: Use e.g. a regex to enforce the format, but don’t expect it to be perfect.
  • Just not just by people: Store the input, but also normalized forms / parts e.g. by using libphonenumber

Thank showing the different paths is really helpful. I am using Twilio for a side project and so its not just real people, its matching up a phone number to phone number automatically, etc. It seems like libphonenumber would be the way to go (I see an elixir port of it).

It seems like Phoenix.HTML.Form works pretty tightly with the changeset by default. Is it usually best to put the validation and converting to a E.164 proper format for then storing in the database all in the ecto changeset, while leaving the form to be just a single string input?

The ex_phone_number library could be useful for you.


I’m using Twilio as well, so I store the number in the DB in Twilio-compatible format. For the presentation I use Cleave.js and do the conversion in the controller since I treat the formatting as the UI concern.

Thank you thats good to hear. Right now I have it taking a country code and national number from the form and having a changeset function that validates and puts the final e164 format number as the phone number which is stored.

Cleave.js looks great, I will definitely look into using!

Might not need this anymore, but in this thread I mention a new guide I just wrote where I use ex_phone_number to handle international phone number validations and formatting in a Live View.

Hope it helps :heart:


This might really help you @tnederlof. It uses the ex_phone_number library and creates a custom type for casting the e164 phone number into Ecto. See the cast function:

I am working on a similar issue, no affiliation with them, just found this gem! Many thanks to them :slight_smile: