HTML::Template - how to handle TMPL_LOOP parameter if no rows returned

hmadhi has asked for the wisdom of the Perl Monks concerning the following question:

I am using TMPL_LOOP that works just fine. However when no rows are from the Database I get the following error:

HTML::Template::param() : attempt to set parameter 'logged_events' with a scalar - parameter is not a TMPL_VAR!

relevant code :

my $sth_le = $dbh->prepare($loggedEventsSQL);
$sth_le->execute();
        
my $logged_events ;
push @{$logged_events} , $_ while $_ = $sth_le->fetchrow_hashref();

my $cordr_template = HTML::Template->new(filename=>$pdp_template,
                                            die_on_bad_params =>0,
                                           );
                                                    
$cordr_template->param(
                                   KPI           => $kpi,
                                   THRES       => $pdp_thres,
                                   DATETIME   => $currDateTime,
                                   NEW_EVENTS => $new_events,
                                   LOGGED_EVENTS => $logged_events, );
[download]

Comment on HTML::Template - how to handle TMPL_LOOP parameter if no rows returned Download Code

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Re: HTML::Template - how to handle TMPL_LOOP parameter if no rows returned by moritz (Cardinal) on Mar 04, 2011 at 09:50 UTC
`my $logged_events = [];` should do the trick. But it reads much nicer if you do it this way: `my @logged_events; push @logged_events, $_ while $_ = $sth_le->fetchrow_hashref(); my $cordr_template = HTML::Template->new(filename=>$pdp_template, die_on_bad_params =>0, ); $cordr_template->param( KPI => $kpi, THRES => $pdp_thres, DATETIME => $currDateTime, NEW_EVENTS => $new_events, LOGGED_EVENTS => \@logged_events, ) +;` [download] (modulo some code alignment you could also improve) Perl 6 - second systems done right	[reply] [d/l] [select]
Re^2: HTML::Template - how to handle TMPL_LOOP parameter if no rows returned by hmadhi (Acolyte) on Mar 04, 2011 at 10:06 UTC
Thanks - It now works as expected !!! Also thank you for additional advice	[reply]
Re: HTML::Template - how to handle TMPL_LOOP parameter if no rows returned by scorpio17 (Canon) on Mar 04, 2011 at 18:56 UTC
If you need to handle the special case of having no data, you can do something like this in your template file: `<TMPL_IF LOGGED_EVENTS> <TMPL_LOOP LOGGED_EVENTS> ... </TMPL_LOOP> <TMPL_ELSE> No Data! </TMPL_IF>` [download]	[reply] [d/l]
Re: HTML::Template - how to handle TMPL_LOOP parameter if no rows returned by jfraire (Beadle) on Mar 05, 2011 at 06:44 UTC
You are not doing any bindings or anything in the while loop. Instead of preparing, executing and then fetching one row at a time, your code would be simpler if you used: `my $logged_events = $dbh->selectall_arrayref($loggedEventsSQL);` [download] By doing this you would also get an empty arrayref in case no rows are returned, thus avoiding the error from HTML::Template. Regards, Julio	[reply] [d/l]