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How to clear a hashtable? RRS feed

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    I have this code that creates a hashtable from a sharepoint-list:

    $hashTable = @()
$items = Get-PnpListItem -List "MyList"
{
$HashTable += New-object psobject -Property @{ 
'Datum' = $item.FieldValues.Datum.ToLocalTime().ToString("dd.MM.yyyy")
'00:00 - 07:59' = $item.FieldValues._x0030_0_x003a_00_x0020__x002d__;
'08:00 - 16:59' = $item.FieldValues._x0030_8_x003a_00_x0020__x002d__;
'17:00 - 23:59' = $item.FieldValues._x0031_7_x003a_00_x0020__x002d__;  
'Opmerkingen' = $item.FieldValues.Opmerkingen; 
  } 
} 
$hashTable | Select Datum,'00:00 - 07:59','08:00 - 16:59','17:00 - 23:59',Opmerkingen | epcsv $DesktopPath + "MyList" -NoT

    I want to reuse this code for multiple lists which has the same columns. Instead of creating a hashtable1, hasthable2. But how can I clear the hashtable. And to I need to clear the other variables in the hashtable too?

    Greetings, P

    Saturday, January 12, 2019 6:34 PM

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    I would re-initialize the hash table with:

    $Table = @{}

    Edit: A quick example.

    $HT = @{}
$HT.Add("a",$True)
$HT.Add("b",$True)
$HT.Add("c",$True)
$HT.Add("d",$True)
$HT.Add("e",$True)
$HT.Count
$HT
"---"
$HT = @{}
$HT.Count
    $HT

    Richard Mueller - MVP Enterprise Mobility (Identity and Access)



    • Edited by Richard MuellerMVP Saturday, January 12, 2019 6:51 PM
    • Marked as answer by PeetK Saturday, January 12, 2019 6:52 PM
    Saturday, January 12, 2019 6:42 PM

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    I would re-initialize the hash table with:

    $Table = @{}

    Edit: A quick example.

    $HT = @{}
$HT.Add("a",$True)
$HT.Add("b",$True)
$HT.Add("c",$True)
$HT.Add("d",$True)
$HT.Add("e",$True)
$HT.Count
$HT
"---"
$HT = @{}
$HT.Count
    $HT

    Richard Mueller - MVP Enterprise Mobility (Identity and Access)



    • Edited by Richard MuellerMVP Saturday, January 12, 2019 6:51 PM
    • Marked as answer by PeetK Saturday, January 12, 2019 6:52 PM
    Saturday, January 12, 2019 6:42 PM
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    Do I need  to clear the variables that I use in the hashtable too ($item, $items) ?

    Saturday, January 12, 2019 6:47 PM
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    No need. Per the example I just added to my reply, the hash table is empty.

    Richard Mueller - MVP Enterprise Mobility (Identity and Access)

    Saturday, January 12, 2019 6:50 PM
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    Thnx
    Saturday, January 12, 2019 6:52 PM
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    You are welcome!

    Richard Mueller - MVP Enterprise Mobility (Identity and Access)

    Saturday, January 12, 2019 7:00 PM
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    $hashTable, in the OP's question, is an array, not a hash. So, $hashTable=@() [using parentheses] instead of $hashTable=@{} [using braces].

    Either one will set the $hashTable to an object with no contents, but still . . .

    $h=@{}
$h += New-object psobject -Property @{ 'Datum' = 'stuff' }
    . . . results in an error: "A hash table can only be added to another hash table."

    --- Rich Matheisen MCSE&I, Exchange Ex-MVP (16 years)


    Saturday, January 12, 2019 7:31 PM
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    This is the best, easiest and fastest way to do this if you want a Csv:

    Get-PnpListItem -List MyList |
    ForEach-Object{
        [pscustomobject]@{
            'Datum' = $item.FieldValues.Datum.ToLocalTime().ToString('dd.MM.yyyy')
            '00:00 - 07:59' = $item.FieldValues._x0030_0_x003a_00_x0020__x002d__;
            '08:00 - 16:59' = $item.FieldValues._x0030_8_x003a_00_x0020__x002d__;
            '17:00 - 23:59' = $item.FieldValues._x0031_7_x003a_00_x0020__x002d__;
            'Opmerkingen' = $item.FieldValues.Opmerkingen;
        }
    } |
    Export-Csv $DesktopPath + "MyList" -NoTypeInformation

    \_(ツ)_/

    • Proposed as answer by jrv Saturday, January 12, 2019 8:06 PM
    Saturday, January 12, 2019 8:05 PM
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    I missed entirely that the code used an array. For hash tables I use the .Add method to add (key, value) pairs. I also generally use the .ContainsKey method to ensure uniqueness of keys.

    Richard Mueller - MVP Enterprise Mobility (Identity and Access)



    Saturday, January 12, 2019 8:10 PM
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    I missed entirely that the code used an array. For hash tables I use the .Add method to add (key, value) pairs. I also generally use the .ContainsKey method to ensure uniqueness of keys.

    Richard Mueller - MVP Enterprise Mobility (Identity and Access)



    Yes but the OP's example can't create dupes and is really just trying to make an exportable object.  A customobject based on a hash is the cleanest and easiest way to do this.

    We can also just use a calculated select property which is fundamentally the same thing.

    I agree. If you are arbitrarily creating a hash from unknown keys then the "Add" and "Contains" method is best.

    \_(ツ)_/

    Saturday, January 12, 2019 9:00 PM