Convert XML to PSObject

Note: I'm using ConvertTo-XML and cannot use Export-Clixml:

I create a simple PSObject:

$a = New-Object PSObject -Property @{
    Name='New'
    Server = $null
    Database = $null
    UserName = $null
    Password = $null
}

I then convert it into XML using ConvertTo-XML:

$b = $a | Convertto-XML -NoTypeInformation

The XML looks like this:

<?xml version="1.0"?>
<Objects>
  <Object>
    <Property Name="Password" />
    <Property Name="Name">开发者_Python百科;New</Property>
    <Property Name="Server" />
    <Property Name="UserName" />
    <Property Name="Database" />
  </Object>
</Objects>

I'm having trouble figuring out the dot notation or XPath query to extract the attributes/elements and convert $b back to the original PSObject.

You can do this pretty easily with XPath. Although PowerShell usually makes working with XML pretty simple, in this case I think the format using strictly PowerShell syntax would be pretty gross.

filter XmlProperty([String]$Property) {
    $_.SelectSingleNode("/Objects/Object/Property[@Name='$Property']").InnerText
}

$Name = $b | Xmlproperty Name
$Server = $b | XmlProperty Server
# etc...

EDIT: To generically do this for an XML document that contains one or more Object elements, you can do something like this:

function ConvertFrom-Xml($XML) {
    foreach ($Object in @($XML.Objects.Object)) {
        $PSObject = New-Object PSObject
        foreach ($Property in @($Object.Property)) {
            $PSObject | Add-Member NoteProperty $Property.Name $Property.InnerText
        }
        $PSObject
    }
}

ConvertFrom-Xml $b

My variant with unlimited depth.

See examples.

function ConvertFrom-Xml {
<#
.SYNOPSIS
    Converts XML object to PSObject representation for further ConvertTo-Json transformation
.EXAMPLE
    # JSON->XML
    $xml = ConvertTo-Xml (get-content 1.json | ConvertFrom-Json) -Depth 4 -NoTypeInformation -as String
.EXAMPLE
    # XML->JSON
    ConvertFrom-Xml ([xml]($xml)).Objects.Object | ConvertTo-Json
#>
    param([System.Xml.XmlElement]$Object)

    if (($Object -ne $null) -and ($Object.Property -ne $null)) {
        $PSObject = New-Object PSObject

        foreach ($Property in @($Object.Property)) {
            if ($Property.Property.Name -like 'Property') {
                $PSObject | Add-Member NoteProperty $Property.Name ($Property.Property | % {ConvertFrom-Xml $_})
            } else {
                if ($Property.'#text' -ne $null) {
                    $PSObject | Add-Member NoteProperty $Property.Name $Property.'#text'
                } else {
                    if ($Property.Name -ne $null) {
                        $PSObject | Add-Member NoteProperty $Property.Name (ConvertFrom-Xml $Property)
                    }
                }
            } 
        }   
        $PSObject
    }
}

I usually parse xml to hash tables but using the convertto function I grabbed from here I adapted the function to convert to pscustom objects

function xmlNodeToPsCustomObject ($node){
    $hash = @{}
    foreach($attribute in $node.attributes){
        $hash.$($attribute.name) = $attribute.Value
    }
    $childNodesList = ($node.childnodes | ?{$_ -ne $null}).LocalName
    foreach($childnode in ($node.childnodes | ?{$_ -ne $null})){
        if(($childNodesList | ?{$_ -eq $childnode.LocalName}).count -gt 1){
            if(!($hash.$($childnode.LocalName))){
                $hash.$($childnode.LocalName) += @()
            }
            if ($childnode.'#text' -ne $null) {
                $hash.$($childnode.LocalName) += $childnode.'#text'
            }
            $hash.$($childnode.LocalName) += xmlNodeToPsCustomObject($childnode)
        }else{
            if ($childnode.'#text' -ne $null) {
                $hash.$($childnode.LocalName) = $childnode.'#text'
            }else{
                $hash.$($childnode.LocalName) = xmlNodeToPsCustomObject($childnode)
            }
        }   
    }
    return $hash | ConvertTo-PsCustomObjectFromHashtable
}

function ConvertTo-PsCustomObjectFromHashtable { 
    param ( 
        [Parameter(  
            Position = 0,   
            Mandatory = $true,   
            ValueFromPipeline = $true,  
            ValueFromPipelineByPropertyName = $true  
        )] [object[]]$hashtable 
    ); 

    begin { $i = 0; } 

    process { 
        foreach ($myHashtable in $hashtable) { 
            if ($myHashtable.GetType().Name -eq 'hashtable') { 
                $output = New-Object -TypeName PsObject; 
                Add-Member -InputObject $output -MemberType ScriptMethod -Name AddNote -Value {  
                    Add-Member -InputObject $this -MemberType NoteProperty -Name $args[0] -Value $args[1]; 
                }; 
                $myHashtable.Keys | Sort-Object | % {  
                    $output.AddNote($_, $myHashtable.$_);  
                } 
                $output
            } else { 
                Write-Warning "Index $i is not of type [hashtable]"; 
            }
            $i += 1;  
        }
    } 
}