Comparing two deep hash of hashes

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

I have two deep hashes (represented below) - I want to compare the two against each other to create a database difference report. So when I'm finished (against the code below), I would know that I have two column diffs between them ('SOME_DATE' has different type and 'CYCLE_DATE' has different nullable values), as well as I have an extra column in the second hash. I've been using the examples here to walk through the hashes, but I can't see how to effectively compare them / place all the differences into a third array/hash: "differences". Thank you for any/all help that you can provide!

#!/usr/bin/perl -w

use strict;
use Data::Dumper;
my %hash = (
    TABLE_NAME => {
        COLUMN_NAME => {
            'CYCLE_DATE' => { TYPE => 'VARCHAR2(20)', NULLABLE => 'N' 
+},
            'SOME_DATE'  => { TYPE => 'DATE',         NULLABLE => 'N' 
+},
            'AMITRUE'    => { TYPE => 'BOOLEAN',      NULLABLE => 'N' 
+}
        }
    }
);

my %hash2 = (
    TABLE_NAME => {
        COLUMN_NAME => {
            'CYCLE_DATE' => { TYPE => 'VARCHAR2(20)', NULLABLE => 'Y' 
+},
            'SOME_DATE'  => { TYPE => 'SOMEGUY',      NULLABLE => 'N' 
+},
            'AMITRUE'    => { TYPE => 'BOOLEAN',      NULLABLE => 'N' 
+},
            'THE_DUDE'   => { TYPE => 'VARCHAR2(10)', NULLABLE => 'Y' 
+}
        }
    }
);

# works for walking single hash - have just started 
# trying to figure out how I'd do both.
walk_hash(\%hash, \%hash2);

sub walk_hash { 
    my ($h1, $h2) = shift; 
    foreach my $key (keys %$h) { 
        if( ref $h->{$key}) { 
            walk_hash( $h->{$key} );
        } 
        else { 
            print $h->{$key};
        } 
    } 
}
[download]

Comment on Comparing two deep hash of hashes Download Code

Replies are listed 'Best First'.
Re: Comparing two deep hash of hashes by Tux (Canon) on Sep 16, 2011 at 13:23 UTC
If you do not need detailed output, but a simple "flag" of same/diff, Test::More offers `is_deeply (\%hash1, \%hash2, "Comparing my hashes");` [download] If you need a more in-depth analysis, Test::Differences will show you the diffs `eq_or_diff (\%hash1, \%hash2, "Comparing my hashes");` [download] alternative formatting is available in the functions `table_diff`, `unified_diff`, `context_diff`, `oldstyle_diff`, `eq_or_diff_text` and `eq_or_diff_data`. Enjoy, Have FUN! H.Merijn	[reply] [d/l] [select]
Re: Comparing two deep hash of hashes by muba (Priest) on Sep 16, 2011 at 13:30 UTC
There's a typo in the code you provided. `sub walk_hash { my ($h1, $h2) = shift; foreach my $key (keys %$h) { # I presume you mean %$h1 here? if( ref $h->{$key}) { # And $h1->... here? walk_hash( $h->{$key} ); # and here? } else { print $h->{$key}; # and here as well? } } }` [download] Other than that, I suggest you check the modules Tux pointed at, above.	[reply] [d/l]
Re^2: Comparing two deep hash of hashes by Anonymous Monk on Oct 14, 2014 at 11:58 UTC
Hi, This code is not working Thanks, Lakshmareddy.	[reply]
Re: Comparing two deep hash of hashes by raybies (Chaplain) on Sep 16, 2011 at 13:32 UTC
You appear to be sending $hash and $hash2 into local vars, $h1 and $h2, but then using a variable called $h. Not sure where $h ever gets assigned to anything. I think if you "use warnings;" this would be more obvious.	[reply]
Re^2: Comparing two deep hash of hashes by TJRandall (Sexton) on Sep 16, 2011 at 13:44 UTC
Sorry about the typo-s - I was clipping down to make it short and sweet post. I will follow the above advice in Test:More - Thank you!!	[reply]