Rasa NLU in Depth - Part 2: Entity Recognition

What if I have an entity called “label name” and the value are just some random strings? like: “5cb28asdubq”, “test111”, “829label”…

what is the best way to extract this entity? I guess maybe I should just restrict the format of user’s inputs so I can apply regex match? like: “the label number is: (*)”

And I do think it will be super useful for rasa to have a “input box” widget, which can let user type the information inside the box.