Check for valid domain name in a string?

Question

I am using python and would like a simple regex to check for a domain name's validity. I check at least write domain name.

url = 'https://stackoverflow'
        keyword = 'foo'
        with self.assertRaises(ValueError):
            check_keyword(url, keyword)

I try unit testing on url textfield and there is main.py page where I done the validation main.py-

def check_keyword(url, keyword):

if re.match("^(((([A-Za-z0-9]+){1,63}\.)|(([A-Za-z0-9]+(\-)+[A-Za-z0-9]+){1,63}\.))+){1,255}$" ,url):
   return ValueError("Invalid")

Example

• www.google (Invalid)

• https://stackoverflow (Invalid)

Solution

The source of the validators module shows, that this is maybe a little more complex task.

You could use that module:

>>> import validators
>>> validators.domain('example.com')
True

>>> validators.domain('example.com/')
ValidationFailure(func=domain, ...)

Or you can use the RFCs for Domain names to construct your own checker.

Comments

[Marvin Taschenberger]

you should post your code with what you did / tried so far.

[Tejas Thakar]

Possible duplicate of Python check if website exists

[Nathan.Eilisha Shiraini]

Possible duplicate of Domain name validation with RegEx

[Toto]

What is a valid domain name for you? I suggest you to read en.wikipedia.org/wiki/List_of_Internet_top-level_domains

[user3289695]

I am using that same module and the regular expression that it uses looks weird. Also, it gives this domain as valid: "a.aa*com" and I think it shouldn't be, specially because it has got an asterisk as a part of it.

[Akash Wankhede]

validators.domain("example.com") cannot check for subdomains. So, It wiil return True for validators.domain("abc.example.com") also.

[Nemo]

The validators package marks domains with underscores or trailing dots as invalid.