Regex for DateTimeOffset validation in url?

Question

How to validate the date and time in the url that is the correct DateTimeOffset format?

DateTimeOffset format (basically starts with 4 digits of year and end with uppercase Z):

• yyyy-mm-ddZ
• yyyy-mm-ddThh:mm:ssZ
• yyyy-mm-ddThh:mm:ss.fffffZ

Valid DateTimeOffset in the url:

• aaa.com/activityDateTime eq 2022-05-12Z
• aaa.com/activityDateTime eq 2022-05-12T12:00:00Z
• aaa.com/activityDateTime%20eq%202022-05-12T12:00:00Z
• aaa.com/activityDateTime+eq+2022-05-12T12:00:00.123456Z
• aaa.com/activityDateTime gt 2022-03-12Z le 2022-05-12Z

Note: eq means equal, gt means greater than, le means less than

Invalid DateTimeOffset in the url:

• aaa.com/activityDateTime eq 2022-05-12
• aaa.com/activityDateTime eq 2022-05-12T12:00:00
• aaa.com/activityDateTime%20eq%202022-05-12T12:00:00
• aaa.com/activityDateTime+eq+2022-05-12T12:00:00.123456

I'm currently convert the url to string and use Regex to validate it, but not sure what's the proper way to handle the case where url contains "%20". Is there a way not to use Replace()? Also, any other suggestions to validate DateTimeOffset in the url? Here's my current regex expression:

Regex checkDate = new Regex(@"^(?!\d{4}-\d{2}-\d{2}Z)");
Regex checkDateTime = new Regex(@"^(?!\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z)");

Answer 1

If you need a regex to validate DateTimeOffset, you can use the following one:

^[A-Za-z\.\/]+( |%20|\+)(eq|gt)( |%20|\+)[\d\-]+(T[\d:]+(\.[\d]+)?Z|Z( [a-z]+ [\d\-]+Z)?)$

Explanation:

• ^: start string
• [A-Za-z\.\/]+: any combination of alphabetic character, dots and slashes
• ( |%20|\+): single space or %20 or +
• (eq|gt): eq or gt
• ( |%20|\+): single space or %20 or +
• [\d\-]+: any combination of digits and dashes (the date)

The last part (T[\d:]+(\.[\d]+)?Z|Z( [a-z]+ [\d\-]+Z)?) can match one between two different suffixes.

Suffix 1 T[\d:]+(\.[\d]+)?Z:

• T: T
• [\d:]+: any combination of digits and : (the time)
• (\.[\d]+)?: optional presence of single dot with a combination of digits (milliseconds?)
• Z: Z

Suffix 2 Z( [a-z]+ [\d\-]+Z)?:

• Z: Z
• ( [a-z]+ [\d\-]+Z)?: optional presence of a space, followed by letters, a space, combination of digits and dashes (a date), a Z

The whole regex is wrapped up with:

• $: end of string

If instead you want to match only the DateTimeOffset, use only the following part of this regex:

[\d\-]+(T[\d:]+(\.[\d]+)?Z|Z( [a-z]+ [\d\-]+Z)?)$

Test this regex here.