Get specific child items for each parent Item from a converted JSON file in Powershell

Question

We are trying to Pull AP names and two specific Bssid values out of json files provided by network team, in PowerShell 5.1

Started with the following function to get the names (this works for just the names), but am stumped on how to get ChildItems, or if it's even possible to pull child items when searching a string like this, unlikely would be my guess.

Function GetName {
$WapName = get-content $FileName -Raw |
    Select-String -pattern '"name":\s*"?([^",]+)"?,?' -allmatches |  
        Foreach-Object { $_.Matches | ##Get-childItem matching specific ESSID, return macaddr ??
            Foreach-Object { $_.Groups[1].Value}
        }

    if ($null -eq $WapName){
        Write-Host "Array is null"
       }# End of If
    else{
        Write-Host "Array has $($WapName.length) elements"
        $WapName
       }#End of Else

}#End of Function

Thinking we may need to convertFrom-Json to achieve child item pulls, but am unfamiliar with how to work with that data. want to Ultimately get this converted to a csv file for manipulation.

Here's example of JSON file. We need AP Names and each associated wifi macaddr value for the wifitrusted and wifiguest items only. The rest of the data is unneeded.

{
  "aps": [
    {
      "macaddr": "xx:xx:xx:xx:xx:xx",
      "name": "**WAP01**",
      "radio_bssids": [
        {
          "bssids": [
            {
              "essid": "wifiguest",
              "macaddr": "**xx:xx:xx:xx:xx:xx**"
            },
            {
              "essid": "wifitrusted",
              "macaddr": "**xx:xx:xx:xx:xx:xx**"
            },
            {
              "essid": "Wifi-xyz",
              "macaddr": "xx:xx:xx:xx:xx:xx"
            }
          ],
          "index": 0,
          "macaddr": "xx:xx:xx:xx:xx:xx"
        },
        {
          "bssids": [
            {
              "essid": "wifiguest",
              "macaddr": "**xx:xx:xx:xx:xx:xx**"
            },
            {
              "essid": "wifitrusted",
              "macaddr": "**xx:xx:xx:xx:xx:xx**"
            },
            {
              "essid": "Wifi-xyz",
              "macaddr": "xx:xx:xx:xx:xx:xx"
            }
          ],
          "index": 1,
          "macaddr": "xx:xx:xx:xx:xx:xx"
        }
      ],
      "serial": "sjfdgkjafdgl",
      "swarm_id": "kjslkfdjgaofdsgj0w94rlkjo9wrjliwedlkfjwo3"
    },
    {
      "macaddr": "xx:xx:xx:xx:xx:xx",
      "name": "**WAP02**",
      "radio_bssids": [
        {
          "bssids": [
            {
              "essid": "wifiguest",
              "macaddr": "**xx:xx:xx:xx:xx:xx**"
            },
            {
              "essid": "wifitrusted",
              "macaddr": "**xx:xx:xx:xx:xx:xx**"
            },
            {
              "essid": "Wifi-xyz",
              "macaddr": "xx:xx:xx:xx:xx:xx"
            }
          ],
          "index": 0,
          "macaddr": "xx:xx:xx:xx:xx:xx"
        },
        {
          "bssids": [
            {
              "essid": "wifiguest",
              "macaddr": "**xx:xx:xx:xx:xx:xx**"
            },
            {
              "essid": "wifitrusted",
              "macaddr": "**xx:xx:xx:xx:xx:xx**"
            },
            {
              "essid": "Wifi-xyz",
              "macaddr": "xx:xx:xx:xx:xx:xx"
            }
          ],
          "index": 1,
          "macaddr": "xx:xx:xx:xx:xx:xx"
        }
      ],
      "serial": "lasjdhfad",
      "swarm_id": "lkasdjlkajsd;kasdfja;lsdkjffkjlkfj"
    },
  ],
  "count": 2
}

Preferred Output would be something like this repeated for each WAP with ALL records containing wifitrusted and wifiguest:

WAP ESSID   MACAddr
WAP01   wifitrusted xx:xx:xx:xx:xx:xx
WAP02   wifiguest   xx:xx:xx:xx:xx:xx

Thanks for the assist.

Tried going this route in an attempt to get wifiguest to return, this is broken and just a placeholder at this point really as it is not fully what is needed. We are importing the json file into parameter $FileName.

Function GetEssid {
$ESSID = [ordered]@{}
$ESSID = (get-content $FileName -Raw | Convertfrom-Json).PSobject.Properties |
ForEach-Object {$ESSID[$_.essid] = $_.Value }

$ESSID.Stuffs.Where({$_.essid -eq "wifiguest"}).Value

Answer 1

Presumably something like this should help, it's unclear if you just want 2 records as-in your sample or just all records where ESSID is wifiguest or wifitrusted but this should be a start.

$json = Get-Content $FileName -Raw | ConvertFrom-Json
$json.aps | ForEach-Object {
    foreach ($item in $_.radio_bssids) {
        foreach ($bssid in $item.bssids) {
            if ($bssid.essid -in 'wifiguest', 'wifitrusted') {
                [pscustomobject]@{
                    WAP     = $_.name
                    ESSID   = $bssid.essid
                    MACAddr = $bssid.macaddr
                    Index   = $item.index
                }
            }
        }
    }
}

Using the sample Json provided in question the output from the above is:

WAP       ESSID       MACAddr               Index
---       -----       -------               -----
**WAP01** wifiguest   **xx:xx:xx:xx:xx:xx**     0
**WAP01** wifitrusted **xx:xx:xx:xx:xx:xx**     0
**WAP01** wifiguest   **xx:xx:xx:xx:xx:xx**     1
**WAP01** wifitrusted **xx:xx:xx:xx:xx:xx**     1
**WAP02** wifiguest   **xx:xx:xx:xx:xx:xx**     0
**WAP02** wifitrusted **xx:xx:xx:xx:xx:xx**     0
**WAP02** wifiguest   **xx:xx:xx:xx:xx:xx**     1
**WAP02** wifitrusted **xx:xx:xx:xx:xx:xx**     1