hashtable contains $null values

Question

I'm not understanding something. I have a hashtable that contains locations of External Utilities

$ExtUtilities = @{}

Then later on I am adding them into the hash table from an XML document

$ExtUtilities.essclient = $XmlDoc.config.local.setup.external.utility.essclient
$ExtUtilities.lcm       = $XmlDoc.config.local.setup.external.utility.lcm
$ExtUtilities.sqlclient = $XmlDoc.config.local.setup.external.utility.sqlclient
$ExtUtilities.oraexport = $XmlDoc.config.local.setup.external.utility.oraexport

All is fine but I noticed that there are $nulls in the table for each entry and am not sure where they are coming from

Name                           Value
----                           -----
sqlclient                      {$null, $null, C:\Program Files\Microsoft SQL Server\100\Tools\Binn\sqlcmd.exe, $null}
oraexport                      {$null, $null, $null, C:\app\client\epmadmin\product\12.1.0\client_1\BIN\exp.exe}
essclient                      {$null, C:\Oracle\Middleware\EPMSystem11R1\products\Essbase\EssbaseClient\bin\startMaxl.cmd, $null, $null}
lcm                            {C:\Oracle\Middleware\user_projects\Foundation1\bin\Utility.bat, $null, $null, $null}

The $nulls are messing with me running these commands as the CMD interpriter doesn't like the commands that have the leading $nulls.

Anyone can explain why there are $nulls there?

How do you expect us to tell without knowing what your XML document looks like, or how you load it into $XmlDoc? — Ansgar Wiechers
– Ansgar Wiechers, Commented Jan 9, 2017 at 17:20
I'm loading the XML by simply doing a get-content like so $xmlDoc = [xml](Get-Content -path Config.xml), but I think briantist has it right. Thanks for you reply. — todd1215
– todd1215, Commented Jan 9, 2017 at 17:24

briantist · Accepted Answer · 2017-01-09 17:20:33Z

3

Well it's hard to say without seeing your original XML, but likely it's because there are multiple matching elements; the result of of your $XmlDoc.config.local. etc. probably returns an array, and some of the values are $null.

You should be able to filter them out when you do the assignment, something like this:

$ExtUtilities.essclient = $XmlDoc.config.local.setup.external.utility.essclient | 
    Where-Object -FilterScript { $_ }

That will only assign the objects that resolve to $true.

If you really don't want an array, then also get only the first one:

$ExtUtilities.essclient = $XmlDoc.config.local.setup.external.utility.essclient | 
    Where-Object -FilterScript { $_ } |
    Select-Object -First 1

answered Jan 9, 2017 at 17:20

briantist

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1 Comment

todd1215 Over a year ago

Ah...That makes sense. I was starting to think it was something to do with the $xmlDoc but the pattern of $nulls per item kind of threw me off. I figured since I was asking for an explicit xml path that I wouldn't need to do any other filtering and such. Thanks for the reply.

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