How to process Component assignments when moving an issue to another project

[Wade Tracy _Boise_ ID_]

The scenario is we create an issue in a project, it gets auto-assigned using the Component settings.  Later, we need to move the issue to another project and another Component, but the auto-assignment does not trigger.  I also tried with issues that were 'unassigned' but the Component auto-assignment still doesn't trigger on move.  But that's not my problem--I've accepted the behavior and moved on =)

What I want to know if there is a way I can trigger the behavior via a script.  I'm currently working on a Listener in Scriptrunner but I'd rather not recreate the behavior from scratch (are assignments being made by project default, component lead, some other criteria).  Is there a function in the Java API that I can call to cause the assignee to be re-evaluated?  I know it's a stretch, but I thought I would check before I did too much more work.

[Wade Tracy _Boise_ ID_ · Accepted solution]

Okay, I figured it out...if you pass in a -1 for the 'name' value when using the REST API, it is like setting the assignee to Automatic in the UI and will process the assignment rules.  I ran this in the Script Console so there is additional code to grab a test issue, but just remove that and uncomment the line that gets the issue from the event:

import groovyx.net.http.HTTPBuilder
import static groovyx.net.http.ContentType.*
import groovyx.net.http.ContentType
import static groovyx.net.http.Method.*
import com.atlassian.jira.component.ComponentAccessor;

// Remove these lines and uncomment the line below when using in a listener
def issueManager = ComponentAccessor.getIssueManager();
def eventIssue = issueManager.getIssueObject('SB-347');
def components = eventIssue.getComponents();

//def eventIssue = event.getIssue();
def assignee = eventIssue.assignee;
def issueKey = eventIssue.key;
def baseURL = ComponentAccessor.getApplicationProperties().getString("jira.baseurl");

log.debug("Processing auto-assignment for moved issue: " + issueKey);
log.debug("Assignee = " + assignee);

if(!assignee) {
    log.debug("Updating issue for auto-assignment");

    def http = new HTTPBuilder("${baseURL}/rest/api/2/issue/${issueKey}/assignee")
    def authString = 'service:*********'.getBytes().encodeBase64().toString();
    http.request(PUT, ContentType.JSON) {
        requestContentType = ContentType.JSON;
        request.addHeader("authorization: Basic ${authString}", "ContentType: application/json");
        body = [ name: -1 ];

        response.success = { resp, JSON ->
            log.debug(resp.statusLine);
            log.debug("Successful = " + JSON)
        };

        response.failure = { resp, JSON ->
            log.warn(resp.statusLine);
            log.warn("Failed to assign issue to automatic assignment = " + JSON)
        };
    };
}