KBEC-00080 - Using Perl and xPath to find a preceding sibling step relative to the current step

Description

You are in an CloudBees CD (CloudBees Flow) step and you want to access properties (like outcome) stored in a previous step. You want to find a previous step to reference that property.

Solution

Use getJobDetails to create an XML object containing all job steps in the current job.
Use xPath to locate the current job step - the one that your code is running in.
Use the xPath keyword, preceding-sibling to find the preceding step.

Example perl

This example uses xPath to find the current job step and its preceding sibling, and prints a property from that step.

use strict;
use ElectricCommander ();
my $ec = new ElectricCommander->new();
my $xPath = $ec->getJobDetails($ENV{COMMANDER_JOBID});

#  Find the name of the first job step and then the job step ID of that first step
my $firstStepName = $xPath->findvalue(qq#//jobStep[jobStepId="$ENV{COMMANDER_JOBSTEPID}"]/../jobStep[1]/stepName#);
my $firstJobStepId = $xPath->findvalue(qq#//jobStep[jobStepId="$ENV{COMMANDER_JOBSTEPID}"]/../jobStep[stepName="$firstStepName"]/jobStepId#);
print "Id of first job step $firstStepName is $firstJobStepId\n";

#  Find a sibling job step by its position relative to the current job step
my $siblingJobStepId = $xPath->findvalue(qq#//jobStep[jobStepId="$ENV{COMMANDER_JOBSTEPID}"]/preceding-sibling::jobStep[1]/jobStepId#);
print "Id of preceding job step is $siblingJobStepId\n";

#  Find the two steps back sibling step by its position relative to the current job step and show a two job step back property
my $twoBackJobStepId = $xPath->findvalue(qq#//jobStep[jobStepId="$siblingJobStepId"]/preceding-sibling::jobStep[1]/jobStepId#);
my $whichResource = $xPath->findvalue(qq#//jobStep[jobStepId="$siblingJobStepId"]/resourceName#);
print "Id of two job steps back is $twoBackJobStepId using resource $whichResource\n";

Example step parent Javascript

After Commander 3.5, you no longer need to use Perl to find the previous step. Given steps A and B in parallel, step B can refer to step A’s status and outcome as:

echo Status - $[/myParent/jobSteps/A/status]
echo Outcome - $[/myParent/jobSteps/A/outcome]

Example hierarchical Javascript step property retrieval

By at least Commander 3.8 and possibly before, you can use javascript to find arbitrary parent properties.

$[/javascript
function fullStepName(jobStep) {
var result = "";
var parentStep = getProperty(jobStep ,"/myParent");

// Walk up the chain if the parent is not the root step
if (parentStep.stepName != null) { result += fullStepName(parentStep) + "/"; }
result += jobStep.stepName;
return (result);
}
fullStepName(myJobStep);
]

Given procedure A which calls subprocedure B which calls subprocedure C, the above code would produce output:

A/B/C

To retrieve the step name of procedure A from a step in procedure C, use the javascript code:

$[/javascript getProperty(getProperty(myJobStep ,"/myParent") ,"/myParent").stepName;]

javascript will error if the above code does not executed from a subprocedure.

Example Javascript workflow property retrieval

The following code will return the parent’s workflow name if the code is called from a workflow:

$[/javascript if (myJob.callingState != null) {
myJob.callingState.workflow.callingState.workflow.workflowName //logical form
myState.workflow.callingState.workflow.workflowName //alternate form
}
]