I'm writing a set of Apache::ASP scripts that comunicate with a MySQL database using DBI. I'm trying to make sure to catch all errors thrown by DBI (or my own code) and issue rollbacks but I find that it'm always learning better techniques. I ended up having three versions of error catching eval/if blocks so I decided I should look for a dynamic solution.

My latest version is the following:

my $dbh = $base::dbh; # get a database handle

eval {
  # lots of inserts, updates, etc...
};
if ($@) {
  my $err = $@;
  eval { $dbh->rollback };
  # display formatted errors
  $base::showerrors(
    ($base::debug ? $err : "database related error"),
    ($@ ? " error performing rollback\n"
        : " rollback performed successfully\n")
  );
}

[download]

I have now come up with the following solution. I declare a couple of subs at the server startup (in global.asa)

sub dbtry (&@) {
  my ($dbtry, $dbcatch) = @_;

  local $dbh = $base::dbh;
  eval { local $_ = $dbh; &$dbtry };
  if($@) {
    local $_ = "dbcaught:";
    chomp $@;
    $_ .= ($base::debug)
      ? " $@"
      : " database related error";
    eval { $dbh->rollback };
    $_ .= ($@ ? " Error Performing Rollback\n"
              : " Rollback Performed Successfully\n");
    &$dbcatch;
  }
}

sub dbcatch (&) { $_[0] }

[download]

Then I use the following (less cluttered) code to get a job done.

dbtry {
  # lots of inserts, updates, etc...
} dbcatch {
  $base::showerrors("error: $_");
}

[download]

I'm also thinking about merging other error logging mechanisims I use in this code. I've never used this code in practice -- and I'm not entirely convinced that it's the best way to go. Can anyone see anything wrong with this code ? Does anyone know how to improve it ? Any experiences with similar techniques ?

In reply to Catching what DBI throws by Anonymous Monk

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