if(undef($text)) { ...

##</code><code>##

foreach my $row (@{$data_all})
{
    say $row;
    my %currec = %{$row};
    foreach my $columns (keys %currec) {
      my $text = $currec{$columns};
      say $text;
      if(! defined ($text))
      {
        say "$columns is NOT DEFINED";
      }
      elsif (length($text) < 1)
      {
        say "$columns DEFINED, but empty";
      }
    }
    exit;

}