How to access an indexed property on a COM object from Powershell

Question

I'm using Powershell to talk to the Windows 7 task scheduler service via COM through the Task Scheduler 2.0 interfaces (e.g. ITaskDefinition). I want to pull out a particular trigger from the Triggers collection on ITaskDefinition. It appears that the proper way to extract a particular trigger is through the Item property, which is an indexed property.

My first try looks something like this:

$sched = New-Object -Com "Schedule.Service"
$sched.Connect()
$folder = $sched.GetFolder('\')
$task = $folder.GetTask("some task")
$triggers = $task.Definition.Triggers
$trigger = $triggers[0]

However, the last line fails with this message:

Unable to index into an object of type System.__ComObject.

I've tried some other variations on this theme, e.g. $triggers.Item(0), all with no luck. I'm guessing this has to do with $trigger being a COM object, because I think indexed properties work fine on other types.

Does anyone know the correct way to do this?

Keith Hill · Accepted Answer · 2009-11-04 23:31:23Z

8

Item does work. You have to use Item() instead of Item[] and indices are 1-based.

$sched = New-Object -Com "Schedule.Service"
$sched.Connect()
$folder = $sched.GetFolder('\')
$task = $folder.GetTask("Update Bin Dir")
$triggers = $task.Definition.Triggers
$triggers.Item(1)

Type               : 2
Id                 : 67a9fad4-462f-43d9-ab71-6e9b781966e6
Repetition         : System.__ComObject
ExecutionTimeLimit : 
StartBoundary      : 2007-07-02T05:30:00
EndBoundary        : 
Enabled            : True
DaysInterval       : 1
RandomDelay        :

Using an enumerator also works if you don't need to access by index:

foreach ($trigger in $triggers) { $trigger }

edited Nov 4, 2009 at 23:31

answered Nov 3, 2009 at 18:25

Keith Hill

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7 Comments

Charlie Over a year ago

Thanks, this seems to work also. Still hoping someone knows of a more direct way, though.

Keith Hill Over a year ago

Yeah this is bugging me now. :-)

Dustin Venegas Over a year ago

You know, along this same note the following seems to work: foreach($trigger in $task.Definition.Triggers) {$trigger}

Charlie Over a year ago

Very nice; that's what I get for not reading the docs closely enough. Thanks for the effort in tracking this down.

Keith Hill Over a year ago

Been doing .NET for so long, the 1-based index thing stumped me for a while. Thanks to x0n for help on that aspect of the problem.

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Dustin Venegas · Accepted Answer · 2009-11-03 17:55:54Z

3

On my system, it looks like there is only one trigger being returned for some tasks. You might try forcing it to return in an array.

$sched = New-Object -Com "Schedule.Service"
$sched.Connect()
$folder = $sched.GetFolder('\')
$task = $folder.GetTask("some task")
$triggers = @($task.Definition.Triggers)
$trigger = $triggers[0]

answered Nov 3, 2009 at 17:55

Dustin Venegas

7691 gold badge7 silver badges17 bronze badges

2 Comments

Charlie Over a year ago

Cool, this seems like a good workaround. I'm hoping someone will know how to do it "properly", but this will get me going for now.

Carlos Nunez Over a year ago

Awesome workaround. I was trying to cast it to an array, but totally forgot this is the right way to do it for objects like these. Thanks!

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