Is it possible to populate a dropdown field's values with a REST request?

[Charles Ferentchak]

I am wanting to query something outside of JIRA to populate a list of values in a drop down list. I will be creating an Add-In for some other features so writing some code to accomplish it is not an issue. get it an issue...

I can work out caching and whatnot if necessary, I am just wondering if it is even possible?

[Andris Bērziņš]

I have created something similar to this (a treeview of data) so it is possible. What I did was write a JIRA plugin that had a service which retrieved information from outside JIRA and stored it. Then I added REST functions to the same plugin that sent that data. Lastly, I created a custom field text box and added a javascript to its description that used ajax to get data from my REST function and populate the tree. You could probably also create your own custom field instead.