Can anyone help me find ways to copy an issue key into a custom field and if yes what are the ways?

[Kartik Vighne]

Greetings!
If I want to transfer some of my issues from Project A to Project B, in this process the issue key will get updated. After the transfer, is there a way for me to know the previous issue key of the issue?
Following are some of the ways I read about-
1)Adding a custom field and populating it with an issue key
2)Using a Plug-in Script Runner
3)Searching the issues, downloading a CSV file and then re-uploading with a new issue key and old issue key column.
Is there any other more easy comprehensible way to do this?

[Kit Friend · Accepted solution]

You could use Automation for Jira to populate a custom field (or label etc) with the original key I'm sure. 

Why would you need to do this though? 

[Kartik Vighne]

It is one of the Client's Requirements. Thank you 

[Kit Friend]

Sure - but understanding the outcome (what do they hope to use that data for in future?) helps shape the best solution :) 

[Kartik Vighne]

This data is used in times of moving issues from one project to another. Having a field like that could be handy. Hence the requirement.