perlquestion
gryphon
<p>Greetings fellow monks,<p>
<p>After looking over a recent project, I noticed I had written similar code in several sections that effectively did the same thing: Grab data from a database (single query) and build a tree structure from that data. Each time, I was building a structure according to similar rules, so I decided to make a common function.</p>
<p>What I've come up with works, but it has some repeated code. But what concerns me the most is that it's more or less a foreach loop that pushes to an array... which makes me want to rewrite it as a map. Anyway, I've been looking at this for a while and am stuck. I'd like some pointers as to how I could improve the function.</p>
<code>
sub tree_data {
my ( $old_data, $key_name, $next_group, @remaining_keys ) = @_;
my ( @new_data, $last_key, $build_box );
foreach ( @{ $old_data } ) {
if ( $last_key and ( $last_key ne $_->{ $key_name } ) ) {
push @new_data, {
$key_name => $last_key,
$next_group => ( @remaining_keys )
? tree_data( $build_box, @remaining_keys )
: $build_box,
};
undef $build_box;
}
$last_key = delete $_->{ $key_name };
push @{ $build_box }, $_;
}
push @new_data, {
$key_name => $last_key,
$next_group => ( @remaining_keys )
? tree_data( $build_box, @remaining_keys )
: $build_box,
};
return \@new_data;
}
</code>
<readmore>
<p>What I'm trying to accomplish here is take data from a database call and build a tree from it based on key names. Here's some sample input:</p>
<code>
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',
},
];
</code>
<p>Here's some sample output:</p>
<code>
my $output = [
{
'team' => 'A-Team',
'employees' => [
{
'employee' => 'Face',
'work_day' => '2006-08-28',
'other_data' => '123456789',
},
{
'employee' => 'Murdock',
'work_day' => '2006-08-28',
'other_data' => '123456789',
},
],
},
{
'team' => 'Military',
'employees' => [
{
'employee' => 'Decker',
'work_day' => '2006-08-28',
'other_data' => '123456789',
},
],
},
];
</code>
<p>To call the function, I just pass in the data and the key name and sub-group name pairs I want, like this:</p>
<code>
# ...to generate the output example from above...
my $output = tree_data( $input, 'team', 'employees' );
# ...to go a little deeper...
my $output = tree_data(
$input, 'team', 'employees', 'employee', 'work_days'
);
</code>
<p>Going forward, I'm probably going to want to add the ability to pull multiple keys into a particular level, not just a single key; but that's really out of scope for what I'm trying to accomplish right now.</p>
</readmore>
<p>What sort of things should I do to make this function better? Thanks in advance for your suggestions.</p>
<div class="pmsig"><div class="pmsig-25626">
<p>[gryphon]<br/>
<small>Whitepages.com Development Manager (WDDC)</small><br/>
<i>code('Perl') || die;</i></p>
</div></div>