Printing DBI errors from a CGI script

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

Hi

I want to print an error if any DBI functions fail, but
all that happens is I get apache errors.

In the code below, if the SQL insert statement(or connect for that matter) fails I get an "Internal Server error" from apache instead of my print statement.
The apache logs explains why the error occured eg duplicate field, but I want to show the error on the browser.

use strict ;
use CGI qw(param);
use diagnostics ;

sub init {
# Constants
my $db = "edb";
my $server = "localhost";
my $user = "localuser";
my $password = "localpasswd";


# CGI Parameters
my $Id = param("ID");
my $Fname = param("Fname");
# Connect to database
$dbh->{RaiseError} = 1;
my $dbh = DBI->connect("DBI:mysql:$db:$server", $user,$password);

if (! $dbh) {
    print "Could not connect to $db on $server\n";
}
# Prepare and run the query
my $query="INSERT INTO clients values( \"$Fname\",\"$Id\") ;";

my $sth = $dbh->prepare_cached("$query") or die "Can't prepare stateme
+nt: $dbh->errstr \n";
$sth->execute or die "Can't execute statement", $dbh->errstr ;

$sth->finish;
$dbh->disconnect();
    
} # End 
int();
[download]

I have the following setup
Apache 1.3.23
Mod_perl 1.26
Apache::DBI 0.88
AuthMySQL 2.20
Perl 5.6.0
MySQL 3.23.49

Thanks Paul

Comment on Printing DBI errors from a CGI script Download Code

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Re: Printing DBI errors from a CGI script by perlplexer (Hermit) on Apr 18, 2002 at 20:04 UTC
You have RaiseHell set to 1, which means that DBI methods will die on you and print error messages on the screen (where available). Well, guess what? Your browser will surely complain if your script sends an error message instead of the expected HTTP header. You either need to print the HTTP header first `print header; #... do other stuff` [download] or do this `use CGI::Carp qw(fatalsToBrowser);` [download] --perlplexer	[reply] [d/l] [select]
Re: Re: Printing DBI errors from a CGI script by lestrrat (Deacon) on Apr 18, 2002 at 21:03 UTC
... or simply surround the DBI calls with eval().. `my $dbh; eval { ## bunch of dbi calls.. $dbh = DBI->connect( ... ); $dbh->do( blah ); $dbh->commit; $dbh->disconnect; }; if( my $err = $@ ) { eval{ $dbh->rollback }; eval{ $dbh->disconnect }; ## print header, html, and $err exit 1; # or return, whatever }` [download]	[reply] [d/l]
Re: Printing DBI errors from a CGI script by tradez (Pilgrim) on Apr 18, 2002 at 20:01 UTC
Well if you are going to want error reporting to the browser you are going to have a setup an error function and have the 'or' clause or the if(!dbh){} checking point to that. Something like this might work `sub errorHandling { my ($error) = @{{@_}}{qw/error}; print "<html> <head> <title> Error </title> </head> <body> You have the following error <br> $error<br> </body> </html>"; }` [download] Tradez "Never underestimate the predicability of stupidity" - Bullet Tooth Tony, Snatch (2001)	[reply] [d/l]
Re: Printing DBI errors from a CGI script by Ryszard (Priest) on Apr 19, 2002 at 05:24 UTC
I've done lots of web, db programming and have found the method that works best for me is to tail the error_log. Other than that, there is always the fatalsToBrowser thingy or perhaps creating a __DIE__ handler that will print something nice to the browser for you.	[reply]