Re: RFC : AJAX + DBI = DBIx::LiveGrid

[mje]

Thanks for this.

I had a few problems using DBD::ODBC and MS SQL Server. With a table of 1000 rows:

What I found is the data grid displayed the first 70 rows repeatedly as you scrolled. I tracked this down to the SQL being run and then found SQL::Abstract::Limit says $order must be specified when $rows is specified. DBIx::LiveGrid only sets $order if you click on a column heading. I verified this with SQL::Abstract::Limit which produces the following incorrect SQL when $order is not specified:

SELECT * FROM
(
    SELECT TOP 10 * FROM
    (
        SELECT TOP 30  f1, f2 FROM bench_char 
    ) AS foo
    
) AS bar

and the following correct SQL when $order is specified:

SELECT * FROM
(
    SELECT TOP 10 * FROM
    (
        SELECT TOP 30  f1, f2 FROM bench_char ORDER BY f1 ASC
    ) AS foo
    ORDER BY f1 DESC
) AS bar
ORDER BY f1 ASC

I did a rough change to DBIx::LiveGrid to work around this:

sub query_database {
    my($self,$dbh,$table_name,$fields,$where,$order)=@_;
    my $rows     = $self->get('ajax_page_size');
    my $offset   = $self->get('ajax_offset');
    my $sort_dir = $self->get('ajax_sort_dir');
    my $sort_col = $self->get('ajax_sort_col');
       $sort_col = $self->clean_param('sort_col',$sort_col);
    my @porder    = ();
    if ($sort_col) {
        @porder   = ("$sort_col $sort_dir");
        $order = \@porder;
    }
    require SQL::Abstract::Limit;
    my $abstract = SQL::Abstract::Limit->new( limit_dialect => $dbh );
    my( $stmt, @bind ) = $abstract->select( $table_name
                                          , $fields
                                          , $where
                                          , $order
                                          , $rows
                                          , $offset
                                          );

and then changed livegrid.cgi:

my $dbh        = DBI->connect("dbi:ODBC:test", "Martin_Evans", "easyso
+ft", {RaiseError=>1,PrintError=>0});
my $table_name = "bench_char";
my @fields     = qw/f1 f2/;
my @order = qw/f1/;

DBIx::LiveGrid->run( undef, $dbh, $table_name, \@fields, undef, \@orde
+r );

I hope this helps.

BTW, I think there is a bug in IE 6.0.2800.1106 which means the row data is not updated every time when scrolling past the rowset points (70).

[jZed]

Thanks for spotting this and finding the right place to fix. I'll add a default sort-order on the first column but allow programmers to over-ride it.

The Rico site forum has a lot of bug reports and fixes for browser scrolling bugs, I'd imagine they've seen the one you mention, but you might want to post it over there.