Re: Traversing a complex data structure searching for certain keys and printing their values

[choroba]

To get the output you requested, I had to make several assumptions:

1. The %filer_device and %filer_volume type of subhashes are of depth 1 (i.e. @west and @ridge are not structures).
2. %defaults are special and their name must be hardcoded.

#!/usr/bin/perl
use warnings;
use strict;
use v5.14; # Hashrefs for keys and values.

use JSON;
use Data::Dumper;


sub recurse_hash {
    my ($hash, $found, @findkeys) = @_;
    for my $key (sort { # Defaults go first.
                local $a = q() if '%default' eq $a;
                local $b = q() if '%default' eq $b;
                $a cmp $b;
            } keys %{$hash}) {
        my $value = $hash->{$key};
        if ('HASH' eq ref $value) {
            $found = {%$found, %{ recurse_hash($value, $found, @findke
+ys) }};
        }
        for my $find (@findkeys) {
            if ($key eq $find) {
                if ('HASH' eq ref $value) {
                    $found->{$key} = [ map $value->{$_}, sort keys $va
+lue ];
                } else {
                    $found->{$key} = $value;
                }
            }
        }
    }
    if (@findkeys == keys $found) {
        my $count;
        $count = @{ (grep 'ARRAY' eq ref $_, values $found)[0] // [] }
+;
        $count ||= 1;
        for my $i (0 .. $count - 1) {
            print join(':', map {
                                    'ARRAY' eq ref $_ ? $_->[$i] : $_
                                } @{$found}{@findkeys}), "\n";
        }
        print "\n";
        $found = {};
    }
    return $found;
}


my @keylist = qw(%export_name %filer_device %filer_volume %mount_acl
                 %mount_group %mount_user %mount_opts);

my $string = do { local $/; <DATA> };
my $struct = decode_json($string);

recurse_hash($struct, {}, @keylist);


__DATA__
{
    "%name": "Global Central Configuration file",
    "%description": "A representation of nfs mount points for dev mach
+ines",
    "%schema": "schema.conf",
    "@dev": {
        "home_nfs": {
            "%default": {
                "%mount_opts": "nfsvers=3,timeo=600,retrans=2",
                "%mount_user": "root",
                "%mount_group": "root",
                "%mount_acl": "0755"
            },
            "%comment": "----Home NFS Directories----",
            "home-lnk-mpt": {
                "%export_name": "/links",
                "%filer_device": {
                    "@west": "nydevnfs_links",
                    "@ridge": "rnap7750-s"
                },
                "%filer_volume": {
                    "@west": "/vol/links",
                    "@ridge": "/vol/links_c"
                }
            },
            "home7_mpt": {
                "%export_name": "/home7",
                "%filer_device": {
                    "@west": "nydevnfs_home7",
                    "@ridge": "rnap7751-s"
                },
                "%filer_volume": {
                    "@west": "/vol/home7",
                    "@ridge": "/vol/home7_c"
                }
            },
            "home8_mpt": {
                "%export_name": "/home8",
                "%filer_device": {
                    "@west": "nydevnfs_home2",
                    "@ridge": "rnap2114-s"
                },
                "%filer_volume": {
                    "@west": "/vol/home2",
                    "@ridge": "/vol/home2_c"
                }
            }
        }
    }
}

[newperluser2013]

Thanks for your help. This looks really good. Unfortunately I only have perl 5.12 so this fails with these errors

Type of arg 1 to keys must be hash or array (not private variable) at 
+./test.pl line 25, near "$value ]"
Type of arg 1 to keys must be hash or array (not private variable) at 
+./test.pl line 32, near "$found) "
Type of arg 1 to values must be hash or array (not private variable) a
+t ./test.pl line 34, near "$found)"

Also as regards %filer_device and %filer_volume sometimes in this data structure these are not hashes, sometimes both are, and sometimes one is and the other isn't I am really not too sure how to go about dealing with that :-( Also regarding the %defaults section I am not allowed to hardcode that. In the small sample of this data structure I have shown this is tied in to the tag "@dev". So any mountpoint defined under here gets those permissions. In the rest of the data structure I have other tags like @build and @software and under each one of these they have their own set of multiple mount point definitions and their own set of default permissions that need to be set. I ultimately need to print the strings out in the following format without hardcoding any key names in the subroutine I use to parse the data struture. All I can pass to the subroutine is the data structure and the @keylist:

@dev:/links:nydevnfs_links:/vol/links:0755:root:root:nfsvers=3,timeo=6
+00,re
+trans=2
@dev:/links:rnap7750-s:/vol/links_c:0755:root:root:nfsvers=3,timeo=600
+,retr
+ans=2

@dev:/home7:nydevnfs_home7:/vol/home7:0755:root:root:nfsvers=3,timeo=6
+00,re
+trans=2
@dev:/home7:rnap7751-s:/vol/home7_c:0755:root:root:nfsvers=3,timeo=600
+,retr
+ans=2

@dev:/home8:nydevnfs_home2:/vol/home2:0755:root:root:nfsvers=3,timeo=6
+00,re
+trans=2
@dev:/home8:rnap2114-s:/vol/home2_c:0755:root:root:nfsvers=3,timeo=600
+,retr
+ans=2

[choroba]

To fix the first problem, just prepend % to the indicated reference variables.

To the rest, I cannot say more than "Good luck".

[newperluser2013]

Thanks ever so much for your help choroba I have made the changes you suggested and this is now working perfectly :-) Just one thing if you can help. In the sample data structure I posted there is a @dev tag in this and I need to get this value prepended to each line of output. I mustn't hardcode this though. I have other hashes of hashes defined under this whole @dev section which are called @build and @software (which both have loads of mount definitions in )and to each of the lines printed when I parse these I need to prepend the corresponding tag @build/@software. Would you be able to help me with what I need to do here please?

[newperluser2013]

Thanks alot for all your help. As regards prepended % to these variables. Please can you show me where I need to do this? I have tried doing this and I am still getting errors :-(

[newperluser2013]

Thanks alot for all your help. Can you show me where I need to prepend % please?