Selecting objects from a Custom Object

Question

I have a custom PS Object that is something like the below:

ID                           Folder
MyServer01                   \\Server\Share\Share\MyServer01
MyServer02                   \\Server\Share\Share\MyServer02

Naturally the object itself is rather large, with over 1000 entries. I need to be able to select a specific row of the object based on querying the ID.

I thought something like this would work but I'm not having much luck:

$obj | Select-Object | Where-Object ($_.ID -eq "MyServer01")

I need it to return the entire row, so the above (assuming it worked) would return:

MyServer01                   \\Server\Share\Share\MyServer01

EDIT:

foreach ($mf in $Folders.Tables[0]) {
    $Info = New-Object System.Object
    $Info | Add-Member -Type NoteProperty -Name ID -Value $mf.ID
    $Info | Add-Member -Type NoteProperty -Name Folder -Value $mf.Folder
    $obj += $Info
}

Select-Object is unnecessary/redundant. What do you mean by "I'm not having much luck"? What happens? — Mathias R. Jessen
– Mathias R. Jessen, Commented Jan 17, 2016 at 12:53
Can you show us where $obj comes from? How it's assigned/created? — Mathias R. Jessen
– Mathias R. Jessen, Commented Jan 17, 2016 at 13:31
In that case your Where-Object filter should be just fine. Only thing that could mess with it is if the ID has trailing whitespace (ie "MyServer01 "). Try with -match "MyServer01" or -like "*MyServer01*" — Mathias R. Jessen
– Mathias R. Jessen, Commented Jan 17, 2016 at 13:35

Ansgar Wiechers · Accepted Answer · 2016-01-17 17:31:18Z

3

Use a hashtable for storing your objects:

$obj = @{}
foreach ($mf in $Folders.Tables[0]) {
    $Info = New-Object -Type System.Object
    $Info | Add-Member -Type NoteProperty -Name ID -Value $mf.ID
    $Info | Add-Member -Type NoteProperty -Name Folder -Value $mf.Folder
    $obj[$mf.ID] = $Info
}

Don't append to an array in a loop, as that tends to perform poorly.

If your code doesn't depend on the objects being created explicitly as System.Object I'd also recommend to create them as custom objects:

$obj = @{}
foreach ($mf in $Folders.Tables[0]) {
    $Info = New-Object -Type PSCustomObject -Property @{
      'ID'     = $mf.ID
      'Folder' = $mf.Folder
    }
    $obj[$mf.ID] = $Info
}

edited Jan 17, 2016 at 17:31

answered Jan 17, 2016 at 17:22

Ansgar Wiechers

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1 Comment

Mathias R. Jessen Over a year ago

+1 for New-Object -Property @{} over Add-Member, but the real overhead comes from continually resizing the array with +=. Assigning the entire foreach loop directly to the array variable ($obj = foreach(){}) will exhibit the same performance improvement as with a hashtable, with the added advantage that you don't need a distinct identifier per object

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