Question

I’m having an issue accessing some nested data in an XML response using Perl/XML::Simple. An extract of the printed XML reply looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<soapenv:Body>
<ns1:SelectCmDeviceResponse soapenv:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:ns1="http://schemas.cisco.com/ast/soap/">
<SelectCmDeviceResult xsi:type="ns1:SelectCmDeviceResult">
<TotalDevicesFound xsi:type="xsd:unsignedInt">3</TotalDevicesFound>
<CmNodes soapenc:arrayType="ns1:CmNode[3]" xsi:type="soapenc:Array" xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/">
<item xsi:type="ns1:CmNode">
<ReturnCode xsi:type="ns1:RisReturnCode">NotFound</ReturnCode>
<Name xsi:type="xsd:string">10.186.78.4</Name>
<NoChange xsi:type="xsd:boolean">false</NoChange>
<CmDevices soapenc:arrayType="ns1:CmDevice[0]" xsi:type="soapenc:Array"/>
</item>
<item xsi:type="ns1:CmNode">
<ReturnCode xsi:type="ns1:RisReturnCode">Ok</ReturnCode>
<Name xsi:type="xsd:string">10.186.78.68</Name>
<NoChange xsi:type="xsd:boolean">false</NoChange>
<CmDevices soapenc:arrayType="ns1:CmDevice[2]" xsi:type="soapenc:Array">
<item xsi:type="ns1:CmDevice">
<Name xsi:type="xsd:string">SEPD0574CF73FC0</Name>
<IpAddress xsi:type="xsd:string">10.186.79.41</IpAddress>
<DirNumber xsi:type="xsd:string">51251001-Registered,51251004-Registered,51251002-Registered</DirNumber>
<Class xsi:type="ns1:DeviceClass">Phone</Class>
<Model xsi:type="xsd:unsignedInt">404</Model>
<Product xsi:type="xsd:unsignedInt">303</Product>
<BoxProduct xsi:type="xsd:unsignedInt">0</BoxProduct>

Here is the code, which should parse the response and return the IpAddress values of the returned devices:

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;
use XML::Simple;
use LWP;
use SOAP::Lite;

my $cucmip = "10.1.10.1";
my $axl_port = "8443";
my $user = "admin";
my $password = "password";
my $axltoolkit = "http://schemas.cisco.com/ast/soap/action/#RisPort#SelectCmDevice";

sub getDevIp {
    my $message = "<?xml POST message>

    my $url="https://$cucmip:$axl_port/realtimeservice/services/RisPort?wsdl";
    my $ua = LWP::UserAgent->new;
    my $header = new HTTP::Headers (
    'Content-Type' => 'application/xml; charset=utf-8',
    'SOAPAction' => 'http://schemas.cisco.com/ast/soap/action/#RisPort#SelectCmDevice',
    );
    my $req = HTTP::Request->new(POST => $url, $header, $message);
    $req->authorization_basic($user,$password);
    my $response = $ua->request($req);
    my $xs = new XML::Simple(KeyAttr=>[]);
    my $data = $xs->XMLin($response->content);
    print $data->{'soapenv:Body'}->{'ns1:SelectCmDeviceResponse'}->{'SelectCmDeviceResult'}->{'CmNodes'}->{'item'}->[0]->{'CmDevices'}->{'item'}->[0]->{'IpAddress'}->{'content'};
}

getDevIp();

Answer 1

This is basically what you have.

$VAR1 = {
    'soapenv:Body' => {
        'ns1:SelectCmDeviceResponse' => {
            'SelectCmDeviceResult' => {
                'CmNodes' => {
                    'item' => [
                        {
                            'xsi:type'  => 'ns1:CmNode',
                            'CmDevices' => {
                                'soapenc:arrayType' => 'ns1:CmDevice[0]',
                                'xsi:type'          => 'soapenc:Array'
                            },
                        },
                    ],
                    # plus some more items with DIFFERENT structure
                },
            },
        },
    },
};

You are trying to access with

$data->{'soapenv:Body'}
    ->{'ns1:SelectCmDeviceResponse'}
        ->{'SelectCmDeviceResult'}
            ->{'CmNodes'}
                ->{'item'}->[0]                # you probably want ->[1] here! (wild guess)
                    ->{'CmDevices'}
                        ->{'item'}->[0]        # this data does not exist
                            ->{'IpAddress'}    # and this does not exist
                                ->{'content'}; # and this

The values that do not exist are created by perl on first access (this is called autovivification) and initialized undef.

That is the reason for your warning.