run.ps1

using namespace System.Net

# Input bindings are passed in via param block.
param($Request, $TriggerMetadata)

$APIName = $TriggerMetadata.FunctionName
Write-LogMessage -user $request.headers.'x-ms-client-principal' -API $APINAME -message 'Accessed this API' -Sev 'Debug'

Function ConvertTo-FlatObject {
        # https://evotec.xyz/powershell-converting-advanced-object-to-flat-object/ - MIT License
        [CmdletBinding()]
        Param (
                [Parameter(ValueFromPipeLine)][Object[]]$Objects,
                [String]$Separator = '.',
                [ValidateSet('', 0, 1)]$Base = 1,
                [int]$Depth = 5,
                [Parameter(DontShow)][String[]]$Path,
                [Parameter(DontShow)][System.Collections.IDictionary] $OutputObject
        )
        Begin {
                $InputObjects = [System.Collections.Generic.List[Object]]::new()
        }
        Process {
                foreach ($O in $Objects) {
                        $InputObjects.Add($O)
                }
        }
        End {
                If ($PSBoundParameters.ContainsKey('OutputObject')) {
                        $Object = $InputObjects[0]
                        $Iterate = [ordered] @{}
                        if ($null -eq $Object) {
                                #Write-Verbose -Message "ConvertTo-FlatObject - Object is null"
                        }
                        elseif ($Object.GetType().Name -in 'String', 'DateTime', 'TimeSpan', 'Version', 'Enum') {
                                $Object = $Object.ToString()
                        }
                        elseif ($Depth) {
                                $Depth--
                                If ($Object -is [System.Collections.IDictionary]) {
                                        $Iterate = $Object
                                }
                                elseif ($Object -is [Array] -or $Object -is [System.Collections.IEnumerable]) {
                                        $i = $Base
                                        foreach ($Item in $Object.GetEnumerator()) {
                                                $Iterate["$i"] = $Item
                                                $i += 1
                                        }
                                }
                                else {
                                        foreach ($Prop in $Object.PSObject.Properties) {
                                                if ($Prop.IsGettable) {
                                                        $Iterate["$($Prop.Name)"] = $Object.$($Prop.Name)
                                                }
                                        }
                                }
                        }
                        If ($Iterate.Keys.Count) {
                                foreach ($Key in $Iterate.Keys) {
                                        ConvertTo-FlatObject -Objects @(, $Iterate["$Key"]) -Separator $Separator -Base $Base -Depth $Depth -Path ($Path + $Key) -OutputObject $OutputObject
                                }
                        }
                        else {
                                $Property = $Path -Join $Separator
                                $OutputObject[$Property] = $Object
                        }
                }
                elseif ($InputObjects.Count -gt 0) {
                        foreach ($ItemObject in $InputObjects) {
                                $OutputObject = [ordered]@{}
                                ConvertTo-FlatObject -Objects @(, $ItemObject) -Separator $Separator -Base $Base -Depth $Depth -Path $Path -OutputObject $OutputObject
                                [PSCustomObject] $OutputObject
                        }
                }
        }
}
$TenantFilter = $Request.Query.TenantFilter
try {
        if ($TenantFilter -ne 'AllTenants') {
                $RawGraphRequest = New-GraphGetRequest -uri "https://graph.microsoft.com/beta/$($Request.Query.Endpoint)" -tenantid $TenantFilter -NoPagination [boolean]$Request.query.DisablePagination -ComplexFilter
        }
        else {
                $RawGraphRequest = Get-tenants | ForEach-Object {
                        try {
                                $DefaultDomainName = $_.defaultDomainName
                                $TenantName = $_.displayName
                                New-GraphGetRequest -uri "https://graph.microsoft.com/beta/$($Request.Query.Endpoint)" -tenantid $DefaultDomainName -NoPagination [boolean]$Request.query.DisablePagination -ComplexFilter
                        }
                        catch {
                                continue
                        }
                } | Select-Object @{
                        label      = 'Tenant'
                        expression = { $TenantName }
                    
                }, *

        }
        $GraphRequest = $RawGraphRequest | Where-Object -Property '@odata.context' -EQ $null | ConvertTo-FlatObject 
        $StatusCode = [HttpStatusCode]::OK
}
catch {
        $ErrorMessage = Get-NormalizedError -Message $_.Exception.Message
        $StatusCode = [HttpStatusCode]::Forbidden
        $GraphRequest = $ErrorMessage
}

# Associate values to output bindings by calling 'Push-OutputBinding'.
Push-OutputBinding -Name Response -Value ([HttpResponseContext]@{
                StatusCode = $StatusCode
                Body       = @($GraphRequest)
        })