Parsing comma separated values input in a text (custom) field

[Mayank Chandra]

I need to parse comma separated input (multiple usernames) [from a text (custom) field] and then for each user check their validity against LDAP. Has anyone done something similar in past?

I am looking for code which can be used to parse/split input values delimited by comma 

[Prince Nyeche]

If you can, you should script the solution or probably contact an Atlassian partner who can do custom development.  The latter being the fastest way to get your solution.