Internal/ConvertFrom-Json2.ps1

function ConvertFrom-Json2 {
    [CmdletBinding()]
    param
    (
        [Parameter(
            Mandatory = $true,
            ValueFromPipeline = $true,
            Position = 0
        )]
        [Object[]] $InputObject,

        [Parameter()]
        [int] $MaxJsonLength = [int]::MaxValue
    )

    begin {
        function ConvertFrom-Dictionary {
            param
            (
                [System.Collections.Generic.IDictionary`2[String, Object]]$InputObject
            )

            process {
                $returnObject = New-Object PSObject

                foreach ($key in $InputObject.Keys) {
                    $pairObjectValue = $InputObject[$key]

                    if ($pairObjectValue -is [System.Collections.Generic.IDictionary`2].MakeGenericType([String], [Object])) {
                        $pairObjectValue = ConvertFrom-Dictionary $pairObjectValue
                    }
                    elseif ($pairObjectValue -is [System.Collections.Generic.ICollection`1].MakeGenericType([Object])) {
                        $pairObjectValue = ConvertFrom-Collection $pairObjectValue
                    }

                    $returnObject | Add-Member Noteproperty $key $pairObjectValue
                }

                return $returnObject
            }
        }

        function ConvertFrom-Collection {
            param
            (
                [System.Collections.Generic.ICollection`1[Object]]$InputObject
            )

            process {
                $returnList = New-Object ([System.Collections.Generic.List`1].MakeGenericType([Object]))
                foreach ($jsonObject in $InputObject) {
                    $jsonObjectValue = $jsonObject

                    if ($jsonObjectValue -is [System.Collections.Generic.IDictionary`2].MakeGenericType([String], [Object])) {
                        $jsonObjectValue = ConvertFrom-Dictionary $jsonObjectValue
                    }
                    elseif ($jsonObjectValue -is [System.Collections.Generic.ICollection`1].MakeGenericType([Object])) {
                        $jsonObjectValue = ConvertFrom-Collection $jsonObjectValue
                    }

                    $returnList.Add($jsonObjectValue) | Out-Null
                }

                return $returnList.ToArray()
            }
        }

        $scriptAssembly = [System.Reflection.Assembly]::LoadWithPartialName("System.Web.Extensions")

        $typeResolver = @"
public class JsonObjectTypeResolver : System.Web.Script.Serialization.JavaScriptTypeResolver
{
    public override System.Type ResolveType(string id)
    {
        return typeof (System.Collections.Generic.Dictionary<string, object>);
    }
 
    public override string ResolveTypeId(System.Type type)
    {
        return string.Empty;
    }
}
"@


        try {
            Add-Type -TypeDefinition $typeResolver -ReferencedAssemblies $scriptAssembly.FullName
        }
        catch {
            # This is a relatively common error that's harmless unless changing the actual C#
            # code, so it can be ignored. Unfortunately, it's just a plain old System.Exception,
            # so we can't try to catch a specific error type.
            if (-not $_.ToString() -like "*The type name 'JsonObjectTypeResolver' already exists*") {
                throw $_
            }
        }

        $jsonserial = New-Object System.Web.Script.Serialization.JavaScriptSerializer(New-Object JsonObjectTypeResolver)
        $jsonserial.MaxJsonLength = $MaxJsonLength
    }

    process {
        foreach ($i in $InputObject) {
            $s = $i.ToString()
            if ($s) {
                $jsonTree = $jsonserial.DeserializeObject($s)

                if ($jsonTree -is [System.Collections.Generic.IDictionary`2].MakeGenericType([String], [Object])) {
                    $jsonTree = ConvertFrom-Dictionary $jsonTree
                }
                elseif ($jsonTree -is [System.Collections.Generic.ICollection`1].MakeGenericType([Object])) {
                    $jsonTree = ConvertFrom-Collection $jsonTree
                }

                Write-Output $jsonTree
            }
        }
    }
}