Getting the current hash key in a ForEach-Object loop in powershell

Question

I've got a hash table:

$myHash = @{ 
   "key1" = @{
       "Entry 1" = "one"
       "Entry 2" = "two"
   }
   "key 2" = @{
       "Entry 1" = "three"
       "Entry 2" = "four"
   }
}

I'm doing a loop through to get the objects:

$myHash.keys | ForEach-Object {
    Write-Host $_["Entry 1"]
}

Works fine, but what can I use to figure out which of the keys of $myHash I'm in? $_.Name doesn't return anything. I'm stumped. Help?

OK, so I initially left out the ".keys" part of $myHash.keys in the loop both here and in my testing window, even though they were in the actual script. As it turns out, specifying the .keys value does cause it to work. But Graimer's code works too, even with my original mistake, so he gets the checkmark. — Matt Simmons
– Matt Simmons, Commented Feb 14, 2013 at 18:11

Zombo · Accepted Answer · 2014-10-28 07:11:33Z

38

I like to use GetEnumerator() when looping a hashtable. It will give you a property value with the object, and a property key with it's key/name. Try:

$myHash.GetEnumerator() | % { 
    Write-Host "Current hashtable is: $($_.key)"
    Write-Host "Value of Entry 1 is: $($_.value["Entry 1"])" 
}

edited Oct 28, 2014 at 7:11

Zombo

1

answered Feb 14, 2013 at 18:02

Frode F.

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2 Comments

Jake H Over a year ago

Another common way is: $hash.Keys | %{ "key is: $($_), value is $($hash[$_])" }

Frode F. Over a year ago

It does the same, but requires multiple reads to the hashtable and is more prone to typos

Zombo · Accepted Answer · 2014-10-28 08:01:50Z

5

You can also do this without a variable

@{
  'foo' = 222
  'bar' = 333
  'baz' = 444
  'qux' = 555
} | % getEnumerator | % {
  $_.key
  $_.value
}

edited Oct 28, 2014 at 8:01

answered Oct 28, 2014 at 7:16

Zombo

1

Comments

Zwan · Accepted Answer · 2015-09-30 12:48:06Z

4

here a similare function i used to read ini file.(the value are also a dictionary like yours).

ini file that i transform into hash look like this

[Section1]

key1=value1
key2=value2

[Section2]

key1=value1
key2=value2
key3=value3

From the ini the hashtable look like this (i passed the fonction that do the transformation in to hash):

$Inihash = @{ 
           "Section1" = @{
               "key1" = "value1"
               "key2" = " value2"
           }
           "Section2" = @{
               "key1" = "value1"
               "key2" = "value2"
         "key3" = "value3"
           }
        }

so from the hash table this line will search all the key/value for a given section:

$Inihash.GetEnumerator() |?{$_.Key -eq "Section1"} |% {$_.Value.GetEnumerator() | %{write-host $_.Key "=" $_.Value}}

? = for search where-object equal my section name. % = you have to do 2 enumeration ! one for all the section and a second for get all the key in the section.

edited Sep 30, 2015 at 12:48

answered Sep 30, 2015 at 8:43

Zwan

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1 Comment

Joshua K Over a year ago

Good use of the pipeline and demonstration of nesting. Thanks! This is an excellent example of the power of powershell.

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