Thread: BUG #5054: PDO -> Query returns "" from Boolean type field, if it has false value.

The following bug has been logged online:

Bug reference:      5054
Logged by:          Yujin
Email address:      aloudnoise@mail.ru
PostgreSQL version: 8.3
Operating system:   windows XP SP3
Description:        PDO -> Query returns "" from Boolean type field, if  it
has false value.
Details:

When i get query from table with bolean type fields, that have false value ,
function PDO -> fetch  return that fields with not "0" value , but empty
string.

"Yujin" <aloudnoise@mail.ru> writes:
> When i get query from table with bolean type fields, that have false value ,
> function PDO -> fetch  return that fields with not "0" value , but empty
> string.

Are you sure the field is actually false, and not null?

If so, this is a PDO bug, not a Postgres bug.

            regards, tom lane

Tom Lane wrote:
> "Yujin" <aloudnoise@mail.ru> writes:
>
>> When i get query from table with bolean type fields, that have false value ,
>> function PDO -> fetch  return that fields with not "0" value , but empty
>> string.
>>
>
> Are you sure the field is actually false, and not null?
>
> If so, this is a PDO bug, not a Postgres bug.
>
>             regards, tom lane
>
>
Does seem to be a PDO bug or some sort:

Trying out some code with Php 5.3.1-dev:

$sql = "SELECT false";
$stmt = $dbh->query($sql);
$result = $stmt->fetch(PDO::FETCH_NUM);
print("  " . $result[0] . "\n");

reproduces what Yujin is seeing, whereas replacing $sql with:

$sql = "SELECT false::int4";

gives a 0 in the result array. I guess it must be something funny with
how PDO represents the bool type...(will have a look at the PDI code).
But this needs to be raised on bugs.php.net.

Cheers

Mark

Mark Kirkwood wrote:
> I guess it must be something funny with how PDO represents the bool
> type...(will have a look at the PDO code). But this needs to be raised
> on bugs.php.net.
>
>
>
FYI - a related bug is : http://bugs.php.net/bug.php?id=33876

I wrote:
>
>
> Trying out some code with Php 5.3.1-dev:
>
> $sql = "SELECT false";
> $stmt = $dbh->query($sql);
> $result = $stmt->fetch(PDO::FETCH_NUM);
> print("  " . $result[0] . "\n");
>
> reproduces what Yujin is seeing...

After a bit of digging through the PDO code, I see what is happening.
the ->fetch operation is returning a Php boolean correctly from PDO (you
can use var_dump($result[0]) to check this), but when you use print as
above, Php casts the boolean to string - and for whatever reason Php
reckons turning (boolean)false into (string)"" is the way to go. So to
get a sensible result you need to do something like:

$result = $stmt->fetch(PDO::FETCH_NUM);
print("  " . (integer) $result[0] . "\n");

i.e: explicit cast on the result value.

This is confusing and seemingly not consistent - for instance the Mysql
version of this example returns a string "0" from PDO, so gives a 0 for
false in a more expected/intuitive way...

regards

Mark