RegexValidator for Zipcodes

Question

I have been working with Django and RegexValidator on a field where I would only like to save a valid US Zipcode in the format of DDDDD or DDDDD-DDDD.

I have set up my variable in the model as the following:

zip = models.CharField(
    max_length=10,
    null=True,
    blank=True,
    help_text=_("Zipcode"),
    validators=[RegexValidator(
        regex=r'^(^[0-9]{5}(?:-[0-9]{4})?$)?$)',
        message=_(u'Must be valid zipcode in formats 12345 or 12345-1234'),
    )],
)

At this point, I am trying to create a regex that will also save empty strings as well. I have tried to look at the following questions RegEx for 5 digit zip or empty Regex empty string or email and tried adding a "|" before, as well as an "?" at the end.

Any other suggestions or advice?

Answer 1

I believe you just want this as your regex: ^(^[0-9]{5}(?:-[0-9]{4})?$|^$)

It matches either an 5 digit string followed by an option dash and four digits or an empty string.

This was tested in the online regex tester