Perl: How to store array data in hash and extract again

Question

I'm collecting a bunch of data from multiple servers. I need to store some of the server data and compare against other certain server data. So I don't need an array for each server I'd like to store it in a hash, but I'm having issues actually getting the data in/out of the hash.

foreach my $cluster_type (sort keys %{$href_server_list}){
    foreach my $server (sort @{$href_server_list->{$cluster_type}}){
        my @a_cmd_results = ();
        get_server_data(\@a_cmd_results,$server);
        if($cluster_type eq "TYPEA"){
            push @{$GLOBAL_HASH_TYPEA_DATA{$server}}, @a_cmd_results;
        }
        elsif($cluster_type eq "TYPEB"){
            push @{$GLOBAL_HASH_TYPEB_DATA{$server}}, @a_cmd_results;
        }


my @TYPEA;
my @TYPEB;
my $server;
#loop through the 4 different servers
for(my $i=0;$i<4;$i++){
    $server=$TYPEA_keys[$i];
    push @TYPEA, @{$GLOBAL_HASH_TYPEA_DATA{$server}};#error here, "Cant use an undefined value as an ARRAY reference
    $server=$TYPEB_keys[$i];
    push @TYPEB, @{$GLOBAL_HASH_TYPEB_DATA{$server}};
    #sort and compare data from TYPEA and TYPEB
}

It "works" if I push a reference instead of the array like this

push @{$GLOBAL_HASH_TYPEA_DATA{$server}}, \@a_cmd_results;

But if it's simply referencing the array @a_cmd_results then that's no good because it's continually reused for each server and would only contain the last server?

Adam Bellaire · Accepted Answer · 2021-06-02 19:06:47Z

1

You should construct a new array reference in-place using the contents of @a_cmd_results, like this:

push @{$GLOBAL_HASH_TYPEA_DATA{$server}}, [@a_cmd_results];

The [...] syntax in Perl returns an array reference for the list of values inside, as opposed to the (...) syntax which is just a plain list.

answered Jun 2, 2021 at 19:06

Adam Bellaire

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1 Comment

babno Over a year ago

It appears that that is now storing the address of the data and my compare is failing. The values that get put in @TYPEA[0] = "ARRAY(0x2668508) and there is no @TYPEA[1].

babno · Accepted Answer · 2021-06-03 18:14:38Z

0

Seems like push was an issue. While simply trying to assign something equal to an array would typically give you it's length, square brackets changes that. As such the solution was as follows

$GLOBAL_HASH_TYPEA_DATA{$server} = [@a_cmd_results];
my @TYPEA = @{$GLOBAL_HASH_TYPEA_DATA{$server}};

answered Jun 3, 2021 at 18:14

babno

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