Malcolm on 26 Jan 2004 23:02:47 -0000

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Re: perl DBI question

On Monday 26 Jan 2004 4:07 pm, Phil Lawrence wrote:

> Malcolm wrote:
> > my $hash = {'some'=>'data'};
> > my $quoted = $dbh->quote($hash->{'some'});
> > at which point $quoted is undefined.

> I suggest 1, 2, or 3 things:
> 1.  Use Data::Dumper;
>      print Dumper($hash);

Which results in some odd things:

my $hash = {'some'=>'data'};
print $dbh->quote($hash->{'some'});
print Dumper($hash);


$VAR1 = { 'some' => 'data' }; 

However, using the actual data:

print Dumper($session);

$VAR1 = { 'errors' => undef, 'refering_page' => '', 'name' => undef, 'logged 
in' => 'y', 'cookie' => '0167d73142462923e29ef694839a26c2', 'username' => 
'tESTING', 'previous args' => undef, '_session_id' => 
'0167d73142462923e29ef694839a26c2', 'redirect' => undef, 'last used' => 
1075156417 }; 

my $username = $session->{'username'};
print $username;
gives: 				tESTING

print $session->{'username'};
gives:				tESTING

print $$session{'username'}; 
gives:				tESTING

print $dbh->quote( $session->{'username'} );
gives:				NULL

print $dbh->quote( ${ \$session->{'username'} } ); 
gives:				NULL

my %session = %$session;
print $dbh->quote( $session{username} );
gives:				'tESTING'

print $dbh->quote($username);
gives:				'tESTING' 

> 2.  Not a suggestion, but did you know that DBI
>      auto-quotes bound in variables?

In theory. As I was dealing with some fairly simple SQL I didn't consider 

> 3.  sprinkle debug print statements in the DBI
>      source.  The quote method is only a few lines long...

Erm... how?
Editing doesn't seem to have any effect (added a "warn" with the 
parameters as an initial test, restarted apache, nothing shows in the error 

On Monday 26 Jan 2004 4:14 pm, Gay, Jerry wrote:

> have you dumped the hash reference to make sure the value for the 'some'
> key is defined?

Yes, see above.

> then again... since the variable is tied, it might be the cause of the
> problem. 

It's looking that way. If I get the data via the tied hash, it doesn't work. 
If I assign exactly the same data to a normal hash, it works.

> you might be able to create an anonymous temp variable to get around it,
> something like:
>     my $quoted= $dbh->quote( ${ \$hash->{'some'} } );

That didn't work, see above.

> DBI has been used so often, by so many, that if there's a bug in the
> quoting function when using tied variables, i'd expect it's been discovered
> and fixed already. but it's probably worth it to have a look at the source
> for quote, as phil suggested.

I would have thought so too, which is why this surprised me and I assumed it 
was something I was doing wrong.

I finally found searchterms that turned up something useful on google: which confirms the tied hash issue. (It 
is dated May 2000... I'd have thought someone would have solved it by now).

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