Trouble getting data out of a hash

wruehl has asked for the wisdom of the Perl Monks concerning the following question:

For some reason Perl is giving me and unitialized variable error when attempting to take a value out of a hash. Is there any other way of getting the data out of the hash? That same code worked before(gathering port data from a switch) so I'm wondering why it isn't working this time.

The exact output for one xml element is as follows:

Pairname is: RP261

value is HASH(0x10b0060)

Use of uninitialized value in concatenation (.) or string at time_script.pl line 56.

StatA is

#!/usr/bin/perl -w
#Status Legend : 1=psNotInstalled,2=psAvailable,3=psBlocked,4=psUnavai
+lable,
#5=psLinkFailure,6=psLinkFailLOL,7=psIntDiags, 8=psExtLoop,9=psPortFai
+l,
#10=psSR,11=psLR,12=psInaccessible,13=psInactive
### This script developed by Bill Ruehl, July 2007
### Version 1.0 This is version 1 of the time check script


use strict;

#modules used
use XML::Simple;
use Net::SNMP;
use XML::Parser;
use XML::Parser::Expat;
our ($data, $xml, $e, $value, $IPAddressA, $OID, $session, $error, $st
+atA,$resmsg);
#create object

# Hard Code OID for port status info
$OID ="1.3.6.1.4.1.289.2.1.1.2.1.11" ;
#Hard Code OID for metrics info
#instantiate a parser

$xml = new XML::Simple;

open LOG, ">>/home/pbkhk/test/log.txt";
# read the XML file
$data = $xml->XMLin("/home/pbkhk/test/timetest.xml");

print LOG "This iteration run at: " . localtime() . "\n" ;

foreach $e (@{$data->{PairedDevices}})
    #Do actions that require use of XML data in this loop possibly
    #call SNMP data gathering and reporting
    {
        print "Pairname is: " . $e->{PairName} . "\n  ";
        print LOG "Pairname is: ". $e->{PairName} . "\n  ";
        $IPAddressA = $e->{DeviceA}->{IPAddress} ;
        #print "IpAddressA is " . $IPAddressA . "\n";
        #print "IpAddressB is " . $IPAddressB . "\n";
        
        if ($e->{ExclusionIndicator} ne "y")  #Check to see if host sh
+ould be ignored
            {
            #print "SNMP test for DeviceA \n";
            ($session,$error) = Net::SNMP->session(Hostname => $IPAddr
+essA,
                                       Community => "public");
        }
            $value = $session->get_request($OID);
    
            print LOG "request error " . $session->error unless (defin
+ed $value);
               
            $session->close;
        
            $statA = $value->{$OID};
            print "value is $value \n" ;
            print "StatA is $statA \n";
            #print "Date and Time for : $e->{PairName} was  $statA \n"
+;
        #print LOG "Date and Time for : $e->{PairName} was  $statA  \n
+";
    }
            
close LOG;
[download]

Thanks,

-Bill

Comment on Trouble getting data out of a hash Download Code

Replies are listed 'Best First'.
Re: Trouble getting data out of a hash by holli (Abbot) on Oct 26, 2007 at 12:58 UTC
If your code worked before and you didn't change anything, the problem is most likely with your data. try `use Data::Dumper; print Dumper($value);` [download] and see if the data is correct. btw, your code is correct (assuming $value is really a hashref). holli, /regexed monk/	[reply] [d/l]
Re: Trouble getting data out of a hash by toolic (Bishop) on Oct 26, 2007 at 13:03 UTC
Use of uninitialized value in concatenation (.) or string at time_script.pl line 56. You could use Data::Dumper to help narrow down the cause of this warning. At the top of your code, add: `use diagnostics; use Data::Dumper;` [download] Later on in your code, use: `print Dumper($value);` [download] diagnostics might also provide more helpful information.	[reply] [d/l] [select]
Re^2: Trouble getting data out of a hash by wruehl (Acolyte) on Oct 26, 2007 at 13:42 UTC
Using Data::Dumper gives me the following: value is HASH(0xe8a5b0) Pairname is: PD110 $VAR1 = {}; It looks like there might be a problem with the stored hash. Any suggestions? -Bill	[reply]
Re^3: Trouble getting data out of a hash by holli (Abbot) on Oct 26, 2007 at 13:50 UTC
First of all, the returned hash is empty so it's no wonder that you the uninitialzed warning. I've never used Net::SNMP but from a quick glance at the docs I see: `$result = $session->get_request( [-callback => sub {},] # non-bloc +king [-delay => $seconds,] # non-bloc +king [-contextengineid => $engine_id,] # v3 [-contextname => $name,] # v3 -varbindlist => \@oids, );` [download] so I think you're call of request is wrong and should read `$result = $session->get_request( -varbindlist => [$OID] );` [download] holli, /regexed monk/	[reply] [d/l] [select]
Re^4: Trouble getting data out of a hash by wruehl (Acolyte) on Oct 26, 2007 at 14:07 UTC


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