Compare-Hashtable

Compare-Hashtable.ps1

function Compare-Hashtable {
<#
.SYNOPSIS
Compare two Hashtable and returns an array of differences.

.DESCRIPTION
The Compare-Hashtable function computes differences between two Hashtables. Results are returned as
an array of objects with the properties: "key" (the name of the key that caused a difference), 
"side" (one of "<=", "!=" or "=>"), "lvalue" an "rvalue" (resp. the left and right value 
associated with the key).

.PARAMETER left 
The left hand side Hashtable to compare.

.PARAMETER right 
The right hand side Hashtable to compare.

.EXAMPLE

Returns a difference for ("3 <="), c (3 "!=" 4) and e ("=>" 5).

Compare-Hashtable @{ a = 1; b = 2; c = 3 } @{ b = 2; c = 4; e = 5}

.EXAMPLE 

Returns a difference for a ("3 <="), c (3 "!=" 4), e ("=>" 5) and g (6 "<=").

$left = @{ a = 1; b = 2; c = 3; f = $Null; g = 6 }
$right = @{ b = 2; c = 4; e = 5; f = $Null; g = $Null }

Compare-Hashtable $left $right

#>	
[CmdletBinding()]
    param (
        [Parameter(Mandatory = $true)]
        [Hashtable]$Left,

        [Parameter(Mandatory = $true)]
        [Hashtable]$Right		
	)
	
	function New-Result($Key, $LValue, $Side, $RValue) {
		New-Object -Type PSObject -Property @{
					key    = $Key
					lvalue = $LValue
					rvalue = $RValue
					side   = $Side
			}
	}
	[Object[]]$Results = $Left.Keys | % {
		if ($Left.ContainsKey($_) -and !$Right.ContainsKey($_)) {
			New-Result $_ $Left[$_] "<=" $Null
		} else {
			if ($Left[$_] -is [hashtable] -and $Right[$_] -is [hashtable] ) {
				Compare-Hashtable $Left[$_] $Right[$_]
			}
			else {
				$LValue, $RValue = $Left[$_], $Right[$_]
				if ($LValue -ne $RValue) {
					New-Result $_ $LValue "!=" $RValue
				}
			}
		}
	}
	$Results += $Right.Keys | % {
		if (!$Left.ContainsKey($_) -and $Right.ContainsKey($_)) {
			New-Result $_ $Null "=>" $Right[$_]
		} 
	}
	if ($Results -ne $null) { $Results }
}

Managed to work it out with help from else where... Code if your interested is here... This tracks the Key/Path as it walks the hashes.

     function Compare-Hashtable {
     [CmdletBinding()]
    param (
    [Parameter(Mandatory = $true)]
    [Hashtable]$Left,

    [Parameter(Mandatory = $true)]
    [Hashtable]$Right,
    [string[]] $path,
    [boolean] $trackpath = $True
)
write-host "Path received as: $path"
function New-Result($Path, $LValue, $Side, $RValue) {
    New-Object -Type PSObject -Property @{
        key    = $Path -Join "/"
        lvalue = $LValue
        rvalue = $RValue
        side   = $Side
    }
}

$Left.Keys | ForEach-Object {
    write-host "*** " $_
    $NewPath = $Path + $_
    if ($trackpath ) {
        write-host "Working on Path: " $NewPath
    }

    if ($Left.ContainsKey($_) -and !$Right.ContainsKey($_)) {
        write-host "Right key not matched. Report path as: $NewPath"
        New-Result $NewPath $Left[$_] "<=" $Null
    }
    else {
        if ($Left[$_] -is [hashtable] -and $Right[$_] -is [hashtable] ) {
             Compare-Hashtable $Left[$_] $Right[$_] $NewPath
        }
        else {
            $LValue, $RValue = $Left[$_], $Right[$_]
            if ($LValue -ne $RValue) {
                New-Result $NewPath $LValue "!=" $RValue
            }
         }

    }
}
$Right.Keys | ForEach-Object {
    $NewPath = $Path + $_
    if (!$Left.ContainsKey($_) -and $Right.ContainsKey($_)) {
        New-Result $NewPath $Null "=>" $Right[$_]

    }
}
 } 
  Compare-Hashtable $Sailings $Flights