Accessing values of object properties in PowerShell

Question

I'm going through an array of objects and I can display the objects fine.

$obj

displays each object in my foreach loop fine. I'm trying to access the object fields and their values. This code also works fine:

$obj.psobject.properties

To just see the names of each object's fields, I do this:

$obj.psobject.properties | % {$_.name}

which also works fine.

When I try to access the values of those field by doing this:

$obj.psobject.properties | % {$obj.$_.name}

nothing is returned or displayed.

This is done for diagnostic purposes to see whether I can access the values of the fields. The main dilemma is that I cannot access a specific field's value. I.e.

$obj."some field"

does not return a value even though I have confirmed that "some field" has a value.

This has baffled me. Does anyone know what I'm doing wrong?

Solution 1

Once you iterate over the properties inside the foreach, they become available via $_ (current object symbol). Just like you printed the names of the properties with $_.Name, using $_.Value will print their values:

$obj.psobject.properties | % {$_.Value}

Solution 2

Operator precedence interprets that in the following way:

($obj.$_).Name

which leads to nothing because you want

$obj.($_.Name)

which will first evaluate the name of a property and then access it on $obj.

Solution 3

You don't have to iterate over all properties if you just need the value of one of them:

$obj.psobject.properties["foo"].value

Comments

[Victor Zakharov]

+1. I suspected something as obvious as this, so went ahead to check, but you posted your answer by the time I came back. As a side note to OP - you could have discovered the Value property by doing this: $obj.psobject.properties | gm.

[starcodex]

I did that for diagnostic purposes to see whether I could access the values of the fields. However when I try to access the value of a certain field that I know exists, like $obj."certain field", nothing is returned

[starcodex]

I thought of that as I usually incorporate parentheses for this exact reason. Still does not yield what I want.

[Rich]

That's weird. A simple test for me was $a = gci | select -f 1; $a.psobject.properties|%{$_.Name + "tt" + $a.($_.Name)} which works just fine.

[x0n]

Another way is with quotes: $obj."$($_.name)"

[Rich]

@x0n: That's a little overkill, though, to use a double-quoted string with a sub-expression when you can just use parentheses (or the sub-expression without the surrounding string).

[gargoylebident]

Whhat is "bla"?