How to convert nested JSON into hashtable in powershell?

Question

I'm trying to convert JSON into hashtable in 5.1 version of Powershell. But the output is coming as an object again for FieldMapping key. Can we get the key value pairs for FieldMapping key?

We have ConvertFrom-Json -AsHashtable in 7.1 version. Ideally trying to get the same o/p in 5.1 as well. What can I try next?

My json:

$json = @'
[
  {
    "EntityType": "IP",
    "FieldMapping": [
      {
        "ColumnName":  "FileHashCustomEntity",
        "Identifier":  "Address"
      }
    ]
  }
]
'@

My code:

$entities = $json | ConvertFrom-Json 
$ht2 = @{}
$hash = $entities.psobject.properties | Foreach { $ht2[$_.Name] = $_.Value }
Write-Host $ht2

My output:

Key   : EntityType
Value : IP
Name  : EntityType
    
Key   : FieldMapping
Value : {@{ColumnName=FileHashCustomEntity; Identifier=Address}}
Name  : FieldMapping

Expected output:

Key   : EntityType
Value : IP
Name  : EntityType

Key   : FieldMapping
Value : {FileHashCustomEntity}
Name  : FieldMapping

Hi jdweng.. tried using the above suggested code. But got o/p in this format: Key : EntityType Value : Microsoft.PowerShell.Commands.Internal.Format.FormatEntryData Name : EntityType Key : FieldMapping Value : {Microsoft.PowerShell.Commands.Internal.Format.FormatStartData, Microsoft.PowerShell.Commands.Internal.Format.GroupStartData, Microsoft.PowerShell.Commands.Internal.Format.FormatEntryData, Microsoft.PowerShell.Commands.Internal.Format.GroupEndData…} Name : FieldMapping — dev333
– dev333, Commented Jan 20, 2023 at 10:22
You need to do this recursively and treat arrays specifically. If this works for you, we can close as duplicate: stackoverflow.com/a/34383413/7571258 — zett42
– zett42, Commented Jan 20, 2023 at 10:22

Mathias R. Jessen · Accepted Answer · 2023-01-20 12:43:19Z

1

Right now you're ending up with a top-level hashtable containing custom objects as entries - what you need to do is convert every object in the resulting object hierarchy recursively.

Here's a simple function that does that:

function Convert-PSCToHashTable
{
  param(
    $InputObject, 
    [int]$Depth = 5
  )

  if($Depth -gt 0){
    if($InputObject -is [System.Collections.IList]){
      return @($InputObject |ForEach-Object {Convert-PSCToHashTable $_ -Depth ($Depth - 1)})
    }

    if($InputObject.psobject.BaseObject -is [System.Management.Automation.PSCustomObject]){
      $ht = @{}
      foreach($prop in $InputObject.psobject.Properties){
        $ht[$prop.Name] = Convert-PSCToHashTable $prop.Value -Depth ($Depth - 1)
      }
      return $ht
    }
  }

  return $InputObject
}

Now you can do:

$object = ConvertFrom-Json $json
$hashtable = Convert-PSCToHashTable $object

$hashtable['FieldMapping']['ColumnName'] # "FileHashCustomEntity"

answered Jan 20, 2023 at 12:43

Mathias R. Jessen

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3 Comments

dev333 Over a year ago

tried to use the above function to convert json to hashtable. I'm trying to send this hashtable to the following command. New-AzSentinelAlertRule -ResourceGroupName $ResourceGroupName -WorkspaceName $WorkspaceName -QueryFrequency 1:00:00 -QueryPeriod 1:00:00 -DisplayName "TesS-2" -Kind Scheduled -Query "SecurityAlert | where TimeGenerated == '99'" -Severity Low -TriggerOperator GreaterThan -TriggerThreshold 10 -EntityMapping $hashtable

dev333 Over a year ago

Facing this error : Invalid data model. [: Invalid length of '0' for 'EntityMappings'. 'EntityMappings' length should be between '1' and '5']

dev333 Over a year ago

How can I send this hashtable to EntityMapping parameter ? Can you please help me out ?

Santiago Squarzon · Accepted Answer · 2025-11-19 14:04:27Z

You can use what's already built-in in .NET Framework, the JavaScriptSerializer Class already handles deserialization into Dictionary<string, object>, there is no need to re-invent the wheel.

$json = @'
[
  {
    "EntityType": "IP",
    "FieldMapping": [
      {
        "ColumnName":  "FileHashCustomEntity",
        "Identifier":  "Address"
      }
    ]
  }
]
'@

Add-Type -AssemblyName System.Web

$serializer = [System.Web.Script.Serialization.JavaScriptSerializer]::new()
$result = $serializer.DeserializeObject($json)
$result

# Key          Value
# ---          -----
# EntityType   IP
# FieldMapping {System.Collections.Generic.Dictionary`2[System.String,System.Object]}

$result.GetType()    # object[]
$result[0].GetType() # Dictionary<string, object>
$result[0]['FieldMapping']

# Key        Value
# ---        -----
# ColumnName FileHashCustomEntity
# Identifier Address

$result[0]['FieldMapping'][0]['ColumnName']

# FileHashCustomEntity

jdweng · Accepted Answer · 2023-01-20 11:10:49Z

-1

This works. Included debug statements so you can see how the data is organized

$json = @" 
[
 
                              {
 
                                  "EntityType": "IP",
 
                                  "FieldMapping":  [
 
                                                       {
 
                                                           "ColumnName":  "FileHashCustomEntity",
                                                            "Identifier":  "Address"
                                                           
 
                                                       }
 
                                                   ]
 
                              }
 
                          ]
"@
$entities = $json | ConvertFrom-Json 
$entities
$ht2 = [System.Collections.ArrayList]::new()
$newRow = New-Object -TypeName psobject
$newRow | Add-Member -NotePropertyName EntityType -NotePropertyValue $entities.EntityType
foreach($property in $entities.FieldMapping)
{
$property | Format-Table
   $newRow | Add-Member -NotePropertyName ColumnName -NotePropertyValue $property.ColumnName  
   $newRow | Add-Member -NotePropertyName Identifier -NotePropertyValue $property.Identifier
 
}
$ht2.Add($newRow)  | Out-Null

$ht2 | Format-Table

answered Jan 20, 2023 at 11:10

jdweng

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1 Comment

Theo Over a year ago

This outputs an ArrayList of PsCustomObjects. Not a Hashtable at all as the OP wants

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