Quick one: Trace out object attributes in JavaScript

By
Joerg Lew
– March 6, 2012Posted in: Examples, Get Started!

I just strumbled (once again) over some scripting objects in vCenter Orchestrator where the documentation in the API Explorer is, eeeh, just missing. So I had to figure out the attributes of the object manually. To do this, you can leverage the JavaScripts’s characteristic that objects are represented as enumerations of their attributes.

So it’s possible to loop through all the attributes even if you don’t know their identifier (yet). Following example in Javascript does exactly that, to trace out all attributes of a VM-Object (Type: VcVirtualMachine) and its Datastores. (you can download the full example below)

The script

//print out properties of a VM-object

//loop through all properties (leverage Javascript's
// "object is an associative array" characteristic)
for (var i in vm) { (//vm is an input parameter of Type VcVirtualMachine
	//we have to catch some 'not defined' errors if object has
	//an attribute of type "dynamic property")
	try {
	//print out in form "propertyname:::value"
		System.debug(i + ":::" + vm[i]);
	} catch (ex) {
		//just ignore error and continue with next iteration(=property)
		continue;
	}
}

//other example: For a datastore
System.debug("================================");
System.debug("====NOW FOR THE DATASTORE===");
System.debug("================================");
var vmsDatastores = vm.datastore;
System.debug("VM's Datastore(-object): " + vmsDatastores);
//vm.datastore return an ARRAY OF DATASTORES itself, so we have
//wrap it in another loop
for (var k in vmsDatastores) {
	var curDatastore = vmsDatastores[k];
	System.debug("******** NEXT DATASTORE: *****");
	System.debug("curDatastore: " + curDatastore);

//same loop as above for each datastore
//play it again, Sam!
for (var j in curDatastore) {
	try{
		System.debug(j + ":::" + curDatastore[j]);
	} catch (ex) {
		continue;
	}
}
//end same loop as above :-) 

} //end loop through Datastore-Array

The results

The output looks like this:

To interpret the results, an example line of the output:

[2012-03-06 09:45:23.844] [D] resourcePool:::DynamicWrapper (Instance) : \\
    [VcResourcePool]-[class com.vmware.vmo.plugin.vi4.model.VimResourcePool] \\
    -- VALUE : ResourcePool<resgroup-98>

The first part resourcePool is the name of the attribute.
After the ::: separator you get the object type [VcResourcePool] of this attribute, the providing class in the vCenter-Plugin of vCO,
and finally after the – separator you get the value of the attribute, in this case it’s with ResourcePool<resgroup-98> a Moref (Managed Object Reference) to the resource pool the VM is located in.

Now you can use the .-Operator in JavaScript to access the attributes, as in line 21 in the script where we do the cram again for all Datastores the VM is related to.

Only caveat: Just from the System.debug()-Output it’s NOT possible to see if an attribute is just a single object or an Array!
(read carefully the example again: vm.datastore (line 21) returns and Array of VcDatastores, but you cannot see this just from the output of line 22)

Conclusion:

Always have the vSphere API Reference open in background when working with vCenter objects in vCO!

Download the example:

Workflow: Trace Out Object Properties
Workflow: Trace Out Object Properties
trace out object properties.workflow
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