AngularJs ng-pattern regex

Question

I am struggling writing a Regex for angular ng-pattern to validate a form input field.An example of the possible inputs are below

Valid input:

@tag1,@tag2,@tag3
@tag1, @tag2, @tag3
@tag1

Invalid Input:

@tag 1
@tag 1, @tag2, @tag  -3
@ta g1, @t ag2

Basically it should allow comma and comma whitespace, but not allow whitespace in between tags.

I have written a REGEX that matches all the invalid input, but when I use this in ng-pattern it does not do the correct validation.

Regex Built: /((^, @|@\s+)|@*[a-zA-Z0-9]* +[a-zA-Z0-9])/g Link: https://regex101.com/r/HMVdLD/1

Any help is much appreciated!

I tried negating the above expression. That does not seem to work either. — Steven.lin
– Steven.lin, Commented Apr 13, 2017 at 12:41
Look, /^@[a-zA-Z0-9]+(?:,\s*@[a-zA-Z0-9]+)*$/ should match all valid ones, and it is much easier. Put it into the ng-pattern attribute value (ng-pattern="/pattern/"). What about leading/trailing whitespace? Do you want it to be allowed in your input field? — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Apr 13, 2017 at 12:44

Wiktor Stribiżew · Accepted Answer · 2017-04-13 12:55:58Z

6

I suggest defining a pattern to match valid inputs, like

ng-pattern="/^@[a-zA-Z0-9]+(?:,\s*@[a-zA-Z0-9]+)*$/"

If you want to disallow leading and trailing whitespace, add ng-trim="false".

Pattern details:

^ - start of string
@ - a literal @ symbol
[a-zA-Z0-9]+ - 1+ alphanumerics
(?:,\s*@[a-zA-Z0-9]+)* - 0+ sequences of:
- , - comma
- \s* - 0+ whitespaces
- @[a-zA-Z0-9]+ - same as above
$ - end of string.

answered Apr 13, 2017 at 12:55

Wiktor Stribiżew

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