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powershellpipelinepowershell-4.0

Is the following possible in PowerShell: "Select-Object <Property>.<SubProperty>"?


The scenario: I'm using Select-Object to access properties of a piped object, and one of those properties is itself an object. Let's call it PropertyObject. I want to access a property of that PropertyObject, say Property1. Is there any nice and clean way of accessing Property1, along the lines of:

...| select-object PropertyObject.Property1

While experimenting I can only get it to work if I do something like:

...| select-object {$_.PropertyObject.Property1}

and if I want to display it with a decent column name it gets even messier:

...| select-object @{Name="Property1"; Expression={$_.PropertyObject.Property1}}

Given how clean and concise PowerShell is in general, I can't help thinking I'm missing something and there should be a cleaner way of accessing a property of a property. Is there?

EDIT: As requested by Matt, here is the concrete example:

I'm reading an XML file, Books3.xml:

<?xml version="1.0"?>
<catalog>
   <book id="bk101">
      <author>Gambardella, Matthew</author>
      <title>XML Developer's Guide</title>
      <genre>Computer</genre>
      <price>44.95</price>
      <publish_date inprint="false">2000-10-01</publish_date>
      <description>An in-depth look at creating applications 
      with XML.</description>
      <publisher>
        <name>Simon and Schuster</name>
        <country>USA</country>
        <city>New York</city>
      </publisher>
   </book>
   <book id="bk102">
      <author>Ralls, Kim</author>
      <title>Midnight Rain</title>
      <genre>Fantasy</genre>
      <price>5.95</price>
      <publish_date inprint="true">2000-12-16</publish_date>
      <description>A former architect battles corporate zombies, 
      an evil sorceress, and her own childhood to become queen 
      of the world.</description>
      <publisher>
        <name>HarperCollins</name>
        <country>USA</country>
        <city>New York</city>
      </publisher>
   </book>
   <book id="bk103">
      <author>Corets, Eva</author>
      <title>Maeve Ascendant</title>
      <genre>Fantasy</genre>
      <price>5.95</price>
      <publish_date inprint="false">2000-11-17</publish_date>
      <description>After the collapse of a nanotechnology 
      society in England, the young survivors lay the 
      foundation for a new society.</description>
      <publisher>
        <name>Macmillan</name>
        <country>United Kingdom</country>
        <city>London</city>
      </publisher>
   </book>
</catalog>

Code to load XML into XmlDocument:

$filePath = "C:\Temp\books3.xml"
$xmlDoc = new-object xml
$xmlDoc.load($filePath)

Attempting to read details for each book:

$xmlDoc.catalog.book | select author, title, publisher.name

Result:

author                     title                      publisher.name
------                     -----                      --------------
Gambardella, Matthew       XML Developer's Guide
Ralls, Kim                 Midnight Rain
Corets, Eva                Maeve Ascendant

Solution

  • It would be easier if you had something actual repeatable for us to test but we can fake that with Get-Items return.

    (Get-Item C:\temp\logoutput).Parent.Name
    

    .Parent is actually a System.IO.DirectoryInfo object. I use PowerShell 3.0 dot notation to get the name of the parent

    The same result can be acquired by chaining the select calls

    Get-Item C:\temp\logoutput | select -expand Parent | Select -Expand name
    

    This of course would work in PowerShell 2.0 but is not a terse and the 3.0 version.

    Post Question Edit

    Not sure what you are hoping for. What you have does work at extracting sub properties the way you have it. I can only offer an alternate approach that might be more intuitive and friendly but the result is the same.

    $xml.catalog.book | ForEach-Object{
        $_ | Add-Member NoteProperty "PublisherName" $_.publisher.name -PassThru}
    

    Of course you might still need to use select to get your output restricted to the properties you need but it is another option.