Can I select a property and a sub-property in a Powershell one-liner

Question

I am trying to get a JSON array of MAC addresses and associated IP addresses of DHCP leases from a Windows DHCP server using PowerShell.

Using this: Get-DhcpServerv4Lease -ScopeId 192.168.0.0 | Where-Object {$_.AddressState -eq "ActiveReservation"} | Select-Object -Property ClientId,IPAddress | ConvertTo-Json

I get this output:

[
  {
    "ClientId": "00-11-22-33-44-55",
    "IPAddress": {
      "Address": 12345678,
      "AddressFamily": 2,
      "ScopeId" : null,
      "IPAddressToString": "192.168.0.2"
    }
  },
  {
    "ClientId": "00-11-22-33-44-66",
    "IPAddress": {
      "Address": 12345679,
      "AddressFamily": 2,
      "ScopeId" : null,
      "IPAddressToString": "192.168.0.3"
    }
  }
]

But I only want the ClientId and value of IPAddressToString, not the other properties:

[
  {
    "ClientId": "00-11-22-33-44-55",
    "IPAddressToString": "192.168.0.2"
  },
  {
    "ClientId": "00-11-22-33-44-66",
    "IPAddressToString": "192.168.0.3"
  }
]

Is this possible in a one-liner?

codaamok · Accepted Answer · 2020-09-09 09:07:35Z

2

Try this

Get-DhcpServerv4Lease -ScopeId 192.168.0.0 | Where-Object { $_.AddressState -eq "ActiveReservation" } |  Select-Object -Property ClientId, @{Name = "Address"; Expression = { $_.IpAddress.IPAddressToString} } | ConvertTo-Json

edited Sep 9, 2020 at 9:07

codaamok

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answered Sep 9, 2020 at 9:05

Peter the Automator

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Comments

Theo · Accepted Answer · 2020-09-09 09:17:36Z

Since this returned json is an array, I think you need to loop through the elements like

Get-DhcpServerv4Lease -ScopeId 192.168.0.0 | 
    Where-Object {$_.AddressState -eq "ActiveReservation"} | 
    ForEach-Object {
        $_ | Select-Object ClientId, @{Name = 'IPAddress'; Expression = {$_.IPAddress.IPAddressToString}}
    } | ConvertTo-Json

Output:

[
    {
        "ClientId":  "00-11-22-33-44-55",
        "IPAddress":  "192.168.0.2"
    },
    {
        "ClientId":  "00-11-22-33-44-66",
        "IPAddress":  "192.168.0.3"
    }
]

^{P.S. You can write this as a one-liner, but that would make the code harder to read, easier to make mistakes and there is nothing to be gained by writing LONG lines of code. You'll make things only more difficult for yourself by doing that}

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