Re^3: Generating a Hash of Hashes Recursively to Display Database Hierarchy

[ikegami]

I dare say your join is broken and that's what should be fixed. But it's easy to work with it anyway.

You have:

my $data = [
   [ 'parent1', 'child1a', 'child2a', undef,    ],
   [ 'parent1', 'child1b', 'child2b', 'child3b',],
   [ 'parent1', 'child1c', undef, undef,],
];

You want:

my $data = [
   [ 'parent1', 'child1a' ],
   [ 'parent1', 'child2a' ],
   [ 'parent1', 'child1b' ],
   [ 'parent1', 'child2b' ],
   [ 'parent1', 'child3b' ],
   [ 'parent1', 'child1c' ],
];

Easy! Change

    while (my $row = $sth->fetch()) {
        my ($id, $parent_id) = @$row;
        ...
    }

to

    while (my $row = $sth->fetch()) {
        my ($parent_id, @children_ids) = @$row;
        for my $id (grep defined, @children_ids) {
            ...
        }
    }

[c4onastick]

Ah, my apologies! My short hand with $data got a little too short! $data really looks like this:

my $data = [
   [ 'parent1', 'child1', 'grand_child1', undef,    ],
   [ 'parent1', 'child2', 'grand_child2', 'great_grand_child1',],
   [ 'parent1', 'child3', undef, undef,],
];

Or:

my $data = [
   [ 'parent1',      'child1' ],
   [ 'child1',       'grand_child1' ],
   [ 'parent1',      'child2' ],
   [ 'child2',       'grand_child2' ],
   [ 'grand_child2', 'great_grand_child2' ],
   [ 'parent1',      'child1c' ],
];

But because of our extended table structure, I'm sure how I can (easily) make it look like the second form though.

[ikegami]

With the top:

    while (my $row = $sth->fetch()) {
        for (1..$#$row) { 
            my ($parent_id, $id) = @{$row}[$i-1, $i-0];
            last if !defined($id);
            ...
        }
    }

With the bottom:

    while (my $row = $sth->fetch()) {
        my ($parent_id, $id) = @$row;
        ...
    }