Question

Lots of threads about iterating over an array of hashes, which I do daily. However now I want to iterate over an AoH in and AoH. I’m interested in the array “chapters” because I want to add a hash to each array element of that inner array:

$criteria = [
    {
      'title' => 'Focus on Learning',
      'chapters' => [
                          {
                            'content_id' => '182',
                            'criteria_id' => '1',
                            'title' => 'Focus on Learning',
                          },
                          {
                            'content_id' => '185',
                            'criteria_id' => '1',
                            'title' => 'Teachers Role',
                          },
                          {
                            'content_id' => '184',
                            'criteria_id' => '1',
                            'title' => 'Parents in Class',
                          },
                          {
                            'content_id' => '183',
                            'criteria_id' => '1',
                            'title' => 'Students at Home',
                          }
                        ],
      'tot_chaps' => '4'
    },

This, in theory, is want I want to do.

for my $i ( 0 .. $#$criteria ) {
   for my $j ( 0 .. $#$criteria->[$i]{'chapters'}) {
      print $criteria->[$i]{'chapters'}->[$j]{'title'}."\n";
   }
}

print $criteria->[$i]{'chapters'}->[1]{'title'}."\n"; -> Teachers Role

Answer 1

If you want to add something, just do it. I’m not sure I understood where you want to add what exactly. If you want another key/value pair for each of the chapters, do it like this:

for my $i ( 0 .. $#$criteria ) {
  for my $j ( 0 .. $#{$criteria->[$i]{'chapters'}}) {
    $criteria->[$i]{'chapters'}->[$j]->{'Teachers Role'} = 'Stuff';
  }
}

---

Also, there was a little bug in the code: use $#{$criteria->[$i]{'chapters'}} instead of $#$criteria->[$i]{'chapters'} because the $# part only works until the first ->, so it tries to access ->[$i]{'chapters'} out of the value of $#$criteria which is a number and doesn’t work.