Rails regex email validation with no spaces allowed

Question

I am currently using this code for my email validation:

/\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i

the problem is it still accepts emails with spaces like ab c@gmail.com.

I've tried a lot of variations of the code that should not allow spaces, but instead of refreshing the page with an error message at the top of the form, it gives me this error:

The provided regular expression is using multiline anchors (^ or $), which may present a security risk. Did you mean to use \A and \z, or forgot to add the :multiline => true option?

Answer 1

You are missing start and end anchor tag so you can refer this link Regular expressions with validations in RoR 4 and your correct regex will be,

/^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i

You should try this regex also for email validation, this regex will fulfill your all requirement and checking all the required possible validation.

^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$

and Here is explanation of regex which will be useful for understanding validation

^           #start of the line
  [_A-Za-z0-9-\\+]+ #  must start with string in the bracket [ ], must contains one or more (+)
  (         #   start of group #1
    \\.[_A-Za-z0-9-]+   #     follow by a dot "." and string in the bracket [ ], must contains one or more (+)
  )*            #   end of group #1, this group is optional (*)
    @           #     must contains a "@" symbol
     [A-Za-z0-9-]+      #       follow by string in the bracket [ ], must contains one or more (+)
      (         #         start of group #2 - first level TLD checking
       \\.[A-Za-z0-9]+  #           follow by a dot "." and string in the bracket [ ], must contains one or more (+)
      )*        #         end of group #2, this group is optional (*)
      (         #         start of group #3 - second level TLD checking
       \\.[A-Za-z]{2,}  #           follow by a dot "." and string in the bracket [ ], with minimum length of 2
      )         #         end of group #3
$           #end of the line

Tested output:

Email is valid : abc@yahoo.com , true
Email is valid : abc-100@yahoo.com , true
Email is valid : abc.100@yahoo.com , true
Email is valid : abc111@abc.com , true
Email is valid : abc-100@abc.net , true
Email is valid : abc.100@abc.com.au , true
Email is valid : abc@1.com , true
Email is valid : abc@gmail.com.com , true
Email is valid : abc+100@gmail.com , true
Email is valid : abc-100@yahoo-test.com , true
Email is valid : abc , false
Email is valid : abc@.com.my , false
Email is valid : abc123@gmail.a , false
Email is valid : abc123@.com , false
Email is valid : abc123@.com.com , false
Email is valid : .abc@abc.com , false
Email is valid : abc()*@gmail.com , false
Email is valid : abc@%*.com , false
Email is valid : abc..2002@gmail.com , false
Email is valid : abc.@gmail.com , false
Email is valid : abc@abc@gmail.com , false
Email is valid : ab c@gmail.com , false
Email is valid : abc@gmail.com.1a , false

Answer 2

check this:

/^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i

Answer 3

Trying out your regular expression with different strings shows that it does_not accept something which looks like an email with spaces

'abc@google.com' =~ /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  => 0

'a abc@google.com' =~ /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  => nil

'abc a@google.com' =~ /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  => nil

'ab@goo gle.com' =~ /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  => nil

However there are a couple of problems with the regular expression. These strings should not be valid matches, but they are:

'a@google..com' =~ /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  => 0

'first..last@google..com' =~ /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
  => 0

This regular expression avoids this problem: (please note that . needs to be escaped!)

 /\A([\w+\-]+\.)+[\w+\-]+@([a-z\d\-]+\.)+[a-z]+\z/i

But it is still not general enough.

You might want to check this question to improve the regexp:

What characters are allowed in an email address?

However, here is thought you might want to consider instead:

Don't validate the email with regexp, but rather validate implicitly by requiring the user to click on a link in a confirmation email you sent him/her

To implement a confirmation email, you can use Devise confirmable or build it manually: Rails - Add Email Confirmation to Registration System

A confirmation email is far easier and more straight-forward than trying to find the perfect regular expression for all email addresses in the world.

Answer 4

You can use URI::MailTo::EMAIL_REGEXP

Answer 5

Please try this regex once. I have tried that this regex solves the check of whitespaces, invalid "@" or "." characters (mostly duplicates).

^(?=.{0,64}@(\S))[A-Za-z0-9_-]+(\.[A-Za-z0-9_-]+)*[^-][A-Za-z0-9-]+(\.[A-Za-z0-9-]+)*(\.[A-Za-z]{1,})(\S)$

I hope it solves the issue.

Hoping for improvement comments.