Lua pattern matching for email address

Question

I having the following code:

if not (email:match("[A-Za-z0-9%.]+@[%a%d]+%.[%a%d]+")) then
     print(false)
end

It doesn't currently catch

 "test@yahoo,ca"  or "[email protected],com"

as an error.

I thought by limiting the input to %a - characters and %d - digits, I would by default catch any punctuation, including commas.

But I guess I'm wrong. Or there's something else that I'm just not seeing. A second pair of eyes would be appreciated.

Answer 1

In the example of "[email protected],com", the pattern matches [email protected] and stops because of the following ,. It's not lying, it does match, just not what you expected. To fix, use anchors:

^[A-Za-z0-9%.]+@[%a%d]+%.[%a%d]+$

You can further simplify it to:

^[%w.]+@%w+%.%w+$

in which %w matches an alphanumeric character.

Answer 2

I had a hard time finding a true email validation function for Lua.

I couldn't find any that would allow some of the special cases that emails to allow. Things like + or quotes are actually acceptable in emails.

I wrote my own Lua function that could pass all the tests that are outlined in the spec for email addresses.

http://ohdoylerules.com/snippets/validate-email-with-lua

I also added a bunch of commentd, so if there is some strange validation that you want to ignore, just remove the if statement for that particular check.