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i was trying to loop through a list of file names in $s4a using ForEach and ForEach-Object and display output. The only two ways i found that generate output are:

  • ForEach ($name in $s4a) {$name.Name}
  • $s4a| ForEach-Object {$_ | Select Name}

Can someone please let me know why the ones below generate nothing, while the above two work?

  • ForEach ($name in $s4a) {Select Name} #No result
  • ForEach ($name in $s4a) {Select $name.Name} #No result
  • $s4a| ForEach-Object {Select$_.Name} #No result
  • $s4a| ForEach-Object {Select Name} #No result

Thanks heaps!

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    Well, because that's not how Select-Object works, basically. An expression like Select Name is valid, but results in nothing because Select-Object takes its input from the pipeline, unless -InputObject is used. Since there is no pipeline in your foreach loops, or in the blocks you pass to ForEach-Object, there is no output. Using -InputObject you can get each of your examples to output something, although there would be little point since it's just more verbose. Commented Jul 25, 2022 at 14:13
  • Does this answer your question? Difference between select-object and using foreach on the same object Commented Jul 25, 2022 at 14:13
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    thanks @jrider for sharing the link - it looks to me "Select -InputObject " can essentially replace ForEach loop in listing out elements inside a variable and hopefully improve on performance? Commented Jul 25, 2022 at 22:48
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    Correct, if you are just needing to display members of your object, a simple select statement is much faster. Also, if you want to get fancy with it you should look into select calculated properties. In your case just put $s4a | select Name or $s4a.Name Commented Jul 26, 2022 at 11:40

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Essentially, it's because your syntax is incorrect for each of the statements that aren't working. In each of the non-working examples, you are not properly referencing the object that you wish the view the 'name' property on.

Select-Object is generally used when accepting an input object from the pipeline but can also identify the object using the -InputObject parameter.

When calling an object property by $object.propertyName, you don't need a select statement.

Instead of ForEach ($name in $s4a) {Select Name}, try this: ForEach ($name in $s4a) {$name | Select Name}

Instaed of ForEach ($name in $s4a) {Select $name.Name}, try this: ForEach ($name in $s4a) {$name.Name}

Instead of $s4a| ForEach-Object {Select$_.Name}, try this: $s4a| ForEach-Object {$_.Name}

Instead of $s4a| ForEach-Object {Select Name}, try this: $s4a| ForEach-Object {$_ | Select Name}

Also, please note that there is a difference in how each method returns information. Select statements return modified versions of the original objects that only contain the properties that you are selecting. Whereas, calling a property directly returns only the value of that property.

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Thanks so much Ian-Mor! this is really helpful and much appreciate the detailed explanation. do you mind if i ask if it's correct say you should never us "Select $object.propertyName" in any instance? i kinda recall seeing this expression somewhere before but unsure how it worked, if you would have any idea?
Another question if you wouldnt mind - can "Select -InputObject " basically replace ForEach/ForEach-Object loop if i were to simply list out elements inside a variable? this way a loop is saved and performance is faster i assume?
If you want to view a property, you can just call it directly: "$object.propertyName".

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