JIRA Cloud - How to have unique value in custom field

[Gerencia PS]

I am using a jira cloud version. Im my instace have a custom field that basically its a serial number (Text Field (single line))  which is coming from external system and user of jira manually enter it.

Now my need is to have this field contain unique field. Ex: 000012345 entered at the time of creation of new task and should not be used again in the same field if some one else trying to create new task.

[Nic Brough -Adaptavist-]

There's no way to do this on Cloud - it does not have the framework to allow you to check that a value is unique either on screen or in a validator.  The best you could do would be a post-function that searches for the value that a user adds and if it finds it, writes a new comment or custom field into the current issue to say that the value has already been used, so you can search for them.

[Gerencia PS]

How would I do to do this post-funcition configuration ?

[Gerencia PS]

@Nic Brough -Adaptavist- How would I do to do this post-funcition configuration ?

[Nic Brough -Adaptavist-]

There's some sample code for setting a custom field over at http://scriptrunner-docs.connect.adaptavist.com/jiracloud/post-functions.html - it also reads custom fields

[Wouter Bruinings]

We would use the Power Script plugin by cprime.

We'd write a validator script, checking if any other ticket in the project would already use that specific value. 

However, this could result in the create transition executing slow, in case a large number of tickets needs to be checked.

[Gerencia PS]

Can you send me that script ?

[Wouter Bruinings]

I cannot, but there is very extensive documentation.