How can I define nested object arrays in Powershell?

Question

I have a list of ciphers that I need to identify and remove, and the easiest way for a non-developer to maintain this list is via a declaration similar to this:

$bannedCiphers = @{
    "RC4 128/128"=@{
        "IsPermitted" = $false
        "AffectedCiphers" = @{
                        "SSL_RSA_WITH_RC4_128_MD5",
                        "SSL_RSA_WITH_RC4_128_SHA",
                        "TLS_RSA_WITH_RC4_128_MD5",
                        "TLS_RSA_WITH_RC4_128_SHA"
        }
    } 
}

Although I'm having trouble creating the correct syntax for nested objects within Powershell.

What is the correct way to create an object with nested properties like the one above?

i would make a custom object with Name = [string], IsPermitted = [bool], and AffectedCiphers = [array]. that could be stored in an array or another collection type. perhaps a hashtable if you will have many such entries - all with a unique key - and need to look them up quickly. — Lee_Dailey
– Lee_Dailey, Commented Oct 31, 2018 at 18:06

Matt Oestreich · Accepted Answer · 2018-10-31 18:47:36Z

This should do the trick...

$bannedCiphers = @{
    "RC4 128/128"= @{
        "IsPermitted" = $false
        "AffectedCiphers" = @(
            "SSL_RSA_WITH_RC4_128_MD5",
            "SSL_RSA_WITH_RC4_128_SHA",
            "TLS_RSA_WITH_RC4_128_MD5",
            "TLS_RSA_WITH_RC4_128_SHA"
        )
    } 
}

Furthermore, the $bannedCiphers hashtable could easily be converted to JSON (and back)

A la...

$bannedCiphers | ConvertTo-Json

...which outputs:

{  
   "RC4 128/128":{  
      "IsPermitted":false,
      "AffectedCiphers":[  
         "SSL_RSA_WITH_RC4_128_MD5",
         "SSL_RSA_WITH_RC4_128_SHA",
         "TLS_RSA_WITH_RC4_128_MD5",
         "TLS_RSA_WITH_RC4_128_SHA"
      ]
   }
}

If you had this data in JSON format to begin with, you could import that into PowerShell like:

$myJsonData = @"
    {  
       "RC4 128/128":{  
          "IsPermitted":false,
          "AffectedCiphers":[  
             "SSL_RSA_WITH_RC4_128_MD5",
             "SSL_RSA_WITH_RC4_128_SHA",
             "TLS_RSA_WITH_RC4_128_MD5",
             "TLS_RSA_WITH_RC4_128_SHA"
          ]
       }
    }
"@

$myNestedCiphers = $myJsonData | ConvertFrom-Json

Pwd9000 · Accepted Answer · 2018-10-31 23:41:26Z

1

I thought I would re-post this answer and clarify my code a bit more using a custom object example.

Original solution without pscustomobject:

$bannedCiphers = @{
    "RC4 128/128"= @{
        "IsPermitted" = $false
        "AffectedCiphers" = @(
            "SSL_RSA_WITH_RC4_128_MD5",
            "SSL_RSA_WITH_RC4_128_SHA",
            "TLS_RSA_WITH_RC4_128_MD5",
            "TLS_RSA_WITH_RC4_128_SHA"
            )
        } 
    "Another RC4"= @{
        "IsPermitted" = $false
        "AffectedCiphers" = @(
            "Cipher1",
            "Cipher2",
            "Cipher3",
            "Cipher4"
            )
        } 
    }

The output of this solution will yield $bannedCiphers output:

Name                           Value
----                           -----
Another RC4                    {IsPermitted, AffectedCiphers}
RC4 128/128                    {IsPermitted, AffectedCiphers}

My solution creating custom objects:

$bannedCiphers2 = [pscustomobject]@{
    "RC4 128/128"= @{
        "IsPermitted" = $false
        "AffectedCiphers" = @(
            "SSL_RSA_WITH_RC4_128_MD5",
            "SSL_RSA_WITH_RC4_128_SHA",
            "TLS_RSA_WITH_RC4_128_MD5",
            "TLS_RSA_WITH_RC4_128_SHA"
            )
        } 
    "Another RC4"= @{
        "IsPermitted" = $false
        "AffectedCiphers" = @(
            "Cipher1",
            "Cipher2",
            "Cipher3",
            "Cipher4"
            )
        } 
    }

The output for my solution will yield $bannedCiphers2 output:

RC4 128/128                    Another RC4
-----------                    -----------
{IsPermitted, AffectedCiphers} {IsPermitted, AffectedCiphers}

original:

$bannedCiphers | Select-Object *

IsReadOnly     : False
IsFixedSize    : False
IsSynchronized : False
Keys           : {Another RC4, RC4 128/128}
Values         : {System.Collections.Hashtable, System.Collections.Hashtable}
SyncRoot       : System.Object
Count          : 2

vs:

$bannedCiphers2 | Select-Object *

RC4 128/128                    Another RC4
-----------                    -----------
{IsPermitted, AffectedCiphers} {IsPermitted, AffectedCiphers}

edited Oct 31, 2018 at 23:41

answered Oct 31, 2018 at 18:52

Pwd9000

1429 bronze badges

4 Comments

Matt Oestreich Over a year ago

His question was more in regards to data type vs object type - why the need to make a PSCustomObject though? Where is the practicality? It's a loosely typed scripting language... you should take advantage of that or switch to C#

Matt Oestreich Over a year ago

This is not apples to apples... you are discovering the difference between data type vs object type... you wouldnt do this in real life.. $bannedCiphers | Select-Object * you would just do $bannedCiphers - in practice, whether PsCustomObject or not, they both do the same exact thing as far as OP is concerned.. and to answer OP's question, I provided an answer based upon data type..

Pwd9000 Over a year ago

@MattOestreich Hi Matt, yes, I know. The reason I pipe the variables to select-object *, is to show the difference between the two. Both will do the job in the end of the day.

Matt Oestreich Over a year ago

No worries! The output of: $bannedCiphers | Select-Object * and this: $bannedCiphers2 | Select-Object * outlines which properties those object types contain. A PSCustomObject is a "custom" type - a hashtable is not a custom type - its a "data type" that is defined in a class somewhere. You see the properties of that class when you do: $bannedCiphers | Select-Object * The "data type" hashtable holds a key/value pair - PSCustomObject is different - it is custom... therefore the properties of that type are also different - this does not change the data behind either type.

ListenSoftware Louise Ai Agent · Accepted Answer · 2021-02-25 00:07:00Z

0

you can also create nested lists in a class.

class cChild{
[string] $id
[string] $field1
}

class cParent{
[string] $id
[string] $field1
[cChild[]] $child_list
}

one or more child classes can be nested in the parent as the variable $child_list. Classes set boundaries for acceptable data parsed from json.

answered Feb 25, 2021 at 0:07

ListenSoftware Louise Ai Agent

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