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I have a problem in my script:

here I set a var remotefilehash:

$remotefilehash = $remotefiles -replace '^[a-f0-9]{32}(  )', '$0=  ' | ConvertFrom-StringData

this creates a hashtable

I then compare those hash's to what I have locally in a hashset

# Create a hash set from the local hashes.

$localHashSet = [System.Collections.Generic.HashSet[string]] $localmd5

# Loop over all remote hashes to find those not among the local hashes.
$diffmd5 = $remotefilehash.Keys.Where({ -not $localHashSet.Contains($_) })

this gets me the hashkeys but I subsequently also need to get the hash values for those keys that are found in the above where ...

Tony
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1 Answers1

5

this creates a hashtable

Actually, it creates an array of hashtables, because ConvertFrom-StringData turns each pipeline input object into a separate hashtable.

To create a single hashtable, join the input lines to form a single string first - note how -join "`n" is applied to the result of the -replace operation in order to form a single, multi-line string:

$remotefilehash = 
  ($remotefiles -replace '^[a-f0-9]{32}(  )', '$0=  ' -join "`n") |
     ConvertFrom-StringData

To enumerate the key-value pairs instead of just the keys (.Keys) of a hashtable(-like) object, you need to use its .GetEnumerator() method:

$diffmd5 = 
  $remotefilehash.GetEnumerator().Where({ -not $localHashSet.Contains($_.Key) })

The reason that an enumerator must be requested explicitly is that PowerShell by default considers a hashtable/dictionary a single object that is passed as a whole through the pipeline / passed to enumeration methods such as the .Where() and .ForEach() array methods.

Note that the output of the above command is not itself a hashtable, but a regular, array-like collection (of type [System.Collections.ObjectModel.Collection[psobject]) whose elements happen to be key-value pair objects.
As such, this output is enumerated in the pipeline.

mklement0
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  • OK a wee bit late but I think there's an issue with this hashset process - going to update the original post – Tony Aug 26 '22 at 20:56
  • @Tony, your updated code is missing the `-join "`n"` part, so `$remotefilehash` is still not a _single_ hashtable. Generally - unless there's a problem with the answer itself - it's better to create a _new_ question post for follow-up questions. – mklement0 Aug 26 '22 at 21:10
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    let me just ask a new quesetion with said new issue – Tony Aug 26 '22 at 21:55