can't flush buffers?

[quagly]

I posted something like this a week ago, but typos in my message kept
anyone from understanding the issue.

I am trying to return each row to the client as it comes from the
database, instead of waiting for all the rows to be returned before
displaying them.  

I have set $|=1 and added $r->flush; after every print statement ( I
realize this is redundant ) but to no avail.  

This is the relevant code:

while ($sth->fetch) {
   $r->print ("",
   map("$_",@cols),
   "");
  $r->rflush;
}

Here is the complete package:

package Sql::Client;

use Apache::Request;
use strict;
use warnings;
use Apache::Constants qw(:common);

my $r;  #request
my $apr;   #Apache::Request 
my $host;  #hostname of remote user
my $sql;#sql to execute

$|=1;

sub getarray ($) { 

my $dbh;  # Database handle
my $sth;# Statement handle
my $p_sql; # sql statement passed as parameter
my @cols;  #column array to bind results
my $titles;   # array ref to column headers

$p_sql = shift;

# Connect
$dbh = DBI->connect (
"DBI:mysql:links_db::localhost",
"nobody",
"somebody",
{
PrintError => 1,# warn() on errors
RaiseError => 0,   # don't die on error
AutoCommit => 1,# commit executes
immediately
}
);

# prepare statment
$sth = $dbh->prepare($p_sql);

$sth->execute;

$titles = $sth->{NAME_uc};
#--
# for minimal memory use, do it this way
@cols[0..$#$titles] = ();
$sth->bind_columns(\(@cols));
$r->print( "");
$r->print ("",
map("$_",@$titles),
"");
while ($sth->fetch) {
$r->print ("",
map("$_",@cols),
"");
$r->rflush;
}
$r->print ("");
return; 
}


sub handler {
$r = shift;
$apr =  Apache::Request->new($r);
$sql = $apr->param('sql') || 'SELECT';
$sql='SELECT' if  $apr->param('reset');

$r->content_type( 'text/html' );
$r->send_http_header;
return OK if $r->header_only;
$host = $r->get_remote_host;
$r->print(<


Hello $host

Sql Client

Enter your Select Statement:

$sql




HTMLEND
$r->rflush;
getarray($sql) unless $sql =~ /^SELECT$/;

$r->print(<

HTMLEND
return OK;
}
1;

Re: can't flush buffer?

[quagly]

oops, typos in my message.

 In fact, I have done just as you suggest, but it doesn't work.

Thanks,
~quagly

Re: can't flush buffer?

[quagly]

Yes, I have read all of that.  That is what I am following.

It just doesn't work.

~quagly

can't flush buffer?

[quagly]

As a test of my new mod_perl abilities I wrote a trivial SQL client.
It works, but if the query returns many rows then it takes a while.
As a first step I thought I would call $r->rflush; with every row
printed but 
this does not work.  I also tried $|=0; with no effect.

Here is the full module, 100 lines.  The rows are printed in getarray
($$)

Any ideas would be appreciated
    ~quagly

package Sql::Client;

use Apache::Request;
use strict;
use warnings;
use Apache::Constants qw(:common);

my $r;  #request
my $apr;   #Apache::Request 
my $host;  #hostname of remote user
my $sql;#sql to execute


sub getarray ($$) {

my $dbh;  # Database handle
my $sth;# Statement handle
my $p_sql; # sql statement passed as parameter
my @cols;  #column array to bind results
my $titles;   # array ref to column headers
my $r;  # maybe if I pass the request it will
work 

$p_sql = shift;
$r = shift;

# Connect
$dbh = DBI->connect (
"DBI:mysql:links_db::localhost",
"nobody",
"somebody",
{
PrintError => 1,# warn() on errors
RaiseError => 0,   # don't die on error
AutoCommit => 1,# commit executes
immediately
}
);

# prepare statment
$sth = $dbh->prepare($p_sql);

$sth->execute;

$titles = $sth->{NAME_uc};
#--
# for minimal memory use, do it this way
@cols[0..$#$titles] = ();
$sth->bind_columns(\(@cols));
print "";
print "",
map("$_",@$titles),
"";
while ($sth->fetch) {
print "",
map("$_",@cols),
 $r->rflush;
}
print "";
return;
}


sub handler {
$r = shift;
$apr =  Apache::Request->new($r);
$sql = $apr->param('sql') || 'SELECT';
$sql='SELECT' if  $apr->param('reset');

$r->content_type( 'text/html' );
$r->send_http_header;
return OK if $r->header_only;
$host = $r->get_remote_host;
$r->print(<


Hello $host

Sql Client

Enter your Select Statement:

$sql




HTMLEND

getarray($sql,$r) unless $sql =~ /^SELECT$/;

$r->print(<

HTMLEND
return OK;
}
1;
~
"";

Should I use CGI.pm?

[quagly]

I am working my way through the eagle book.  I have not used CGI.pm
before.  It is used in many (most?) of the examples.  

Is it worth learning to use it?  

I am not clear whether the authors are using it because the think it is
the best way to go, or because they already know it ( or created it )and
it is convenient.  

I have not done CGI programming before, but have some experience with
java servlets.  It there a compelling reason I should learn it ( other
than that it would help me to understand the book? )

Thanks,
~quagly

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Re: learning for someone like me

[quagly]

This book looks great!  I had seen it before, but assumed that it was all
C.

Thanks for the tip.

~quagly



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learning for someone like me

[quagly]

I am looking for a source of learning, books, sites, whatever.

I am a unix/oracle developer.  I am experienced in perl/DBI.

I thought it would be interesting to learn something about web
development.
I have some experience with HTML, XML-XSLT and Java Servlets, but Java
is not fun.

So I am looking for information on creating dynamic database driven web
sites using perl.

Most of the introductory web development books/sites do little with
databases, and even pride themselves on showing how much you can do
without knowing much about the backend.  Books that look at building
dynamic sites in depth assume you have a strong grounding in CGI/HTML.

Ideas?

~quagly


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