Question

Below is the code

my $results = $session->array_of_hash_for_cursor("check_if_receipts_exist", 0, @params);
next if( scalar @{$results} <= 0 );
$logger->info("Retrieved number of records: ".scalar @$results);
foreach my $row( sort { $results->{$b}->{epoch_received_date} cmp $results->{$a}->{epoch_received_date} } keys %{$results} )
      {
       //logic
      }

‘check_if_receipts_exists’ is a SQL query which returns some results. Which I try to execute this, I am getting the following error,
Bad index while coercing array into hash

I am new to Perl. Can someone please point out the mistake I am making?

Answer 1

Is $results a hash reference or an array reference?

In some places you are using it like an array reference:

scalar @{$results}

and in other places you are using it like a hash reference:

$results->{$b}->{...}
keys %{$results}

It can’t be both (at least not without some heavy overload magic).

If I can infer from the name of the function that sets $results, it should be a reference to a list of hash references, then a few tweaks will set it right:

1. Using @{$results} is correct; this expression is “an array of hash references”
2. The last argument to sort should be a list, but the correct list to pass is @{$results}, not keys %{$results}.
3. Then the parameters $a and $b inside the sort function will be members of @{$results}, that is, they will be hash references. So the comparison to make is

$a->{epoch_received_date} cmp $b->{epoch_retrieve_data}

and not

    $results->{$a}->{...} cmp $results->{$b}->{...}

All together:

my $results = $session->array_of_hash_for_cursor(
   "check_if_receipts_exist", 0, @params);
next if !@$results;
$logger->info("Retrieved number of records: ".@$results);
for my $row (
    sort {
        $b->{epoch_received_date}
          cmp
        $a->{epoch_received_date}
    } @$results
) {
   # logic
}