Re: Build tree data structure from DB (flat) data; function golf

[jdporter]

in reply to Build tree data structure from DB (flat) data; function golf

I find it most convenient to convert to an intermediate format: a hash, keyed by team name.

my %ident_key = ( from => 'team', to => 'team' );
my %recs_key = ( from => 'employee', to => 'employees' );

my %h; # intermediate hash

for ( @$input ) {
    my %r = %$_;
    my $k = delete $r{$ident_key{'from'}};
    push @{ $h{$k} }, \%r;
}

# convert to your desired structure:
my @output = map {
    {
        $ident_key{'to'} => $_,
        $recs_key{'to'} => $h{$_},
    }
} keys %h;

If you need the input order to be preserved, you could use something like Tie-IxHash.

[perlfan]

I was going to suggest a change in data structure as well.

my $input = [
  {
    'team'       => 'A-Team',

    'employee'   => 'Face',
    'work_day'   => '2006-08-28',
    'other_data' => '123456789',
  },
  {
    'team'       => 'A-Team',
    'employee'   => 'Murdock',
    'work_day'   => '2006-08-28',
    'other_data' => '123456789',
  },
  {
    'team'       => 'Military',
    'employee'   => 'Decker',
    'work_day'   => '2006-08-28',
    'other_data' => '123456789',
  },
];

To:

my %input = (
    'A-Team' => {
         {
          'employee'   => 'Face',
          'work_day'   => '2006-08-28',
          'other_data' => '123456789',
         },
         {
          'employee'   => 'Murdock',
          'work_day'   => '2006-08-28',
          'other_data' => '123456789',
         },
      },
   'Military' => {
         {
          'employee'   => 'Decker',
          'work_day'   => '2006-08-28',
          'other_data' => '123456789',
         },
      },
   );

[imp]

The structure's ideal format depends on how it will be used

gryphon's output seems like something intended for HTML::Template, which only accepts scalars or arrays of hashrefs unfortunately. It wouldn't be able to iterate over your proposed structure.