Question

I have some code which needs to ensure some data is in a mysql enum prior to insertion in the database. The cleanest way I’ve found of doing this is the following code:

sub enum_values {     my ( $self, $schema, $table, $column ) = @_;      # don't eval to let the error bubble up     my $columns = $schema->storage->dbh->selectrow_hashref(         'SHOW COLUMNS FROM `$table` like ?',         {},         $column     );      unless ($columns) {         X::Internal::Database::UnknownColumn->throw(             column => $column,             table  => $table,         );     }      my $type = $columns->{Type} or X::Panic->throw(         details => 'Could not determine type for $table.$column',     );      unless ( $type =~ /\Aenum\((.*)\)\z/ ) {         X::Internal::Database::IncorrectTypeForColumn->throw(             type_wanted => 'enum',             type_found  => $type,         );     }     $type = $1;      require Text::CSV_XS;     my $csv = Text::CSV_XS->new;     $csv->parse($type) or X::Panic->throw(         details => 'Could not parse enum CSV data: '.$csv->error_input,     );     return map { /\A'(.*)'\z/; $1 }$csv->fields; } 

We’re using DBIx::Class. Surely there is a better way of accomplishing this? (Note that the $table variable is coming from our code, not from any external source. Thus, no security issue).

Answer 1

No need to be so heroic. Using a reasonably modern version of DBD::mysql, the hash returned by DBI‘s column info method contains a pre-split version of the valid enum values in the key mysql_values:

my $sth = $dbh->column_info(undef, undef, 'mytable', '%');  foreach my $col_info ($sth->fetchrow_hashref) {   if($col_info->{'TYPE_NAME'} eq 'ENUM')   {     # The mysql_values key contains a reference to an array of valid enum values     print 'Valid enum values for $col_info->{'COLUMN_NAME'}: ',            join(', ', @{$col_info->{'mysql_values'}}), '\n';   }   ... }