Powershell, add items in order to hashtable

user_3536324 0
Viewed 597

I have the following sample script

$aDomains = @{}

$aDomains['a-test.nl'] = @{}
$aDomains['b-test.nl'] = @{}
$aDomains['c-test.nl'] = @{}
$aDomains['d-test.nl'] = @{}
$aDomains['e-test.nl'] = @{}

$aDomains

It seems very straight forward, but if I run this script, the output is very unexpected:

$aDomains


Name                           Value                                                                                
----                           -----                                                                                
e-test.nl                      {}                                                                                   
d-test.nl                      {}                                                                                   
b-test.nl                      {}                                                                                   
a-test.nl                      {}                                                                                   
c-test.nl                      {}

How can I get the output to match the order of items being added? I do need to use the @{} on all instances due to what happens next in the script.

Also, adding this in the script has no effect at all:

$aDomains = $aDomains | Sort-Object
powershell sorting hashtable
2 Answers

By default a hashtable is not ordered, as you saw. Since PowerShell 3.0, you can make a hashtable ordered, in which case it will keep the order.

See the below example:

$aDomains = [ordered] @{}

$aDomains['e-test.nl'] = @{}
$aDomains['a-test.nl'] = @{}
$aDomains['b-test.nl'] = @{}
$aDomains['c-test.nl'] = @{}
$aDomains['d-test.nl'] = @{}
$aDomains['e-test.nl'] = @{}

$aDomains

Name                           Value                                                                                
----                           -----                                                                                
e-test.nl                      {}                                                                                   
a-test.nl                      {}                                                                                   
b-test.nl                      {}                                                                                   
c-test.nl                      {}                                                                                   
d-test.nl                      {}

As you can see, the e-test.nl is in the list twice, but only added once at the top, so it does pertain the order of added, and won't add something twice. To get this to work, add the [ordered] tag to the beginning of the hashtable assignment.

Small sidenode though. If you use the .ContainsKey() function, this needs to be changed to .Contains()

user_35363240

If we unwrap this object into it’s individual elements,then we can sort it.

$aDomains= $aDomains.GetEnumerator() | Sort-Object -Property Name
user_122476820
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