Hashtables from ConvertFrom-json have different type from powershells built-in hashtables, how do I make them the same?

Question

I have a json file (test.json) that looks something like this:

{
    \"root\":
    {
        \"key\":\"value\"
    }
}

I\'m loading it into

Answer 1

The example was for a relatively shallow source object (not nested objects in the properties).

Here's a version that will go 2 levels deep into the source object, and should work with your data:

$data = @{}

foreach ($propL1 in $x.psobject.properties.name)
   {
     $data[$propL1] = @{}
     foreach ($propL2 in $x.$propL1.psobject.properties.name)
        {
          $data[$PropL1][$PropL2] = $x.$propL1.$propL2
        }
    }


$data.root.keys

key

Answer 2

@Duncan: If you need to use JSON Input for an command expecting a hashmap though (eg SET-ADUSER), try something like this:

function SetADProperties{
    param($PlannedChanges)
    $UserName = $PlannedChanges.Request.User
    $Properties = @{}
    foreach ($key in ($PlannedChanges.SetADProperties | Get-Member -MemberType NoteProperty).Name)
    {
        $Properties[$key] = $PlannedChanges.SetADProperties.$key
    }
    # Call Set-ADUser only once, not in a loop
    Set-ADUser -Identity $UserName -Replace $Properties
}

$content = Get-Content -encoding UTF8 $FileName
$PlannedChanges = $content | ConvertFrom-Json
SetADProperties $PlannedChanges | Write-Output

Example JSON:

{"SetADProperties":{"postalCode":"01234","l":"Duckburg","employeenumber":"012345678"},
"Request":{"Action":"UserMove","User":"WICHKIND","Change":"CH1506-00023"}}

Answer 3

Here's a quick function to convert a PSObject back into a hashtable (with support for nested objects; intended for use with DSC ConfigurationData, but can be used wherever you need it).

function ConvertPSObjectToHashtable
{
    param (
        [Parameter(ValueFromPipeline)]
        $InputObject
    )

    process
    {
        if ($null -eq $InputObject) { return $null }

        if ($InputObject -is [System.Collections.IEnumerable] -and $InputObject -isnot [string])
        {
            $collection = @(
                foreach ($object in $InputObject) { ConvertPSObjectToHashtable $object }
            )

            Write-Output -NoEnumerate $collection
        }
        elseif ($InputObject -is [psobject])
        {
            $hash = @{}

            foreach ($property in $InputObject.PSObject.Properties)
            {
                $hash[$property.Name] = ConvertPSObjectToHashtable $property.Value
            }

            $hash
        }
        else
        {
            $InputObject
        }
    }
}

Answer 4

The ConvertFrom-Json cmdlet gives you a custom object so you have to access them using dot notation rather than as a subscript. Usually you would know what fields you expect in the JSON so this is actually more useful in general than getting a hash table. Rather than fighting the system by converting back to a hash table, I suggest you work with it.

You can use select with wildcard property names to get at the properties:

PS D:\> $data = @"
{
    "root":
    {
        "key":"value", "key2":"value2", "another":42
    }
}
"@ | ConvertFrom-Json

PS D:\> $data.root | select * | ft -AutoSize

key   key2   another
---   ----   -------
value value2      42



PS D:\> $data.root | select k* | ft -AutoSize

key   key2  
---   ----  
value value2

and Get-Member if you want to extract a list of property names that you can iterate over:

PS D:\> ($data.root | Get-Member -MemberType NoteProperty).Name
another
key
key2

Putting that into a loop gives code like this:

PS D:\> foreach ($k in ($data.root | Get-Member k* -MemberType NoteProperty).Name) {
    Write-Output "$k = $($data.root.$k)"
    }
key = value
key2 = value2

Answer 5

I put this together to handle nested json to hashtables

    function ConvertJSONToHash{
    param(
        $root
    )
    $hash = @{}

    $keys = $root | gm -MemberType NoteProperty | select -exp Name

    $keys | %{
        $key=$_
        $obj=$root.$($_)
        if($obj -match "@{")
        {
            $nesthash=ConvertJSONToHash $obj
            $hash.add($key,$nesthash)
        }
        else
        {
           $hash.add($key,$obj)
        }

    }
    return $hash
}

I have only tested with 4 levels but recursive until it has complete hashtable.