Dialogflow recently introduced the regular expression entity.
In the video below, I explain how to use it. Note: while the video is part of a mini-course, this specific video is completely self-contained. You don’t have to purchase the mini-course to follow this video.
Testimonial for the mini-course:
This course was invaluable for me and my team members to get hands on knowledge as to how Reg Exp works. Especially since DF documentation is so limited and this is a very new feature. I would (recommend this course) , especially for non-programmers. Aravind shows clear examples, and gives suggestions on what to be cautious of. – Christina A