Edit report at http://bugs.php.net/bug.php?id=49510&edit=1
ID: 49510
Comment by: schkovich at gmail dot com
Reported by: m dot kurzyna at crystalpoint dot pl
Summary: boolean validation fails with FILTER_NULL_ON_FAILURE
Status: Assigned
Type: Feature/Change Request
Package: Feature/Change Request
Operating System: Linux
PHP Version: 5.3.0
Assigned To: pajoye
Block user comment: N
New Comment:
filter_var(false,FILTER_VALIDATE_BOOLEAN,FILTER_NULL_ON_FAILURE)
// got NULL, expected false
That does not make sense at all! Further on, I have to agree with
m.kurzyna that since false === (bool)""
filter_var("",FILTER_VALIDATE_BOOLEAN,FILTER_NULL_ON_FAILURE) should
return FALSE and not NULL.
Basically, as implemented, getting FALSE from
filter_var(false,FILTER_VALIDATE_BOOLEAN) means that validation failed.
It appears to be a design problem since filter_var() as
specified will return FALSE if the filter fails making it impossible to
distinguish if filter failed or valid FALSE value is returned.
Therefore, instead returning FALSE if
filter fails perhaps warning could be issued or even better exception
thrown.
On addition when voting I've wrongly selected that I am not using the
same version and the same operating system. Correct ones are:
PHP Version => 5.3.2-1ubuntu4.2
System => Linux schkovich 2.6.32-24-generic #42-Ubuntu SMP Fri Aug 20
14:21:58 UTC 2010 x86_64
Previous Comments:
------------------------------------------------------------------------
[2009-09-10 11:24:37] m dot kurzyna at crystalpoint dot pl
As much as i'd like to have empty string be invalid false cast i have to
disagree with you for consistency reasons.
If (boolean)'' == false then filter_var('','boolean') should also return
false. Both in general and in case of FILTER_NULL_ON_FAILURE (just like
the documentation states).
Also, because i can't stress it enough, this is a VALIDATOR not a
SANITIZER so using it as a strict caster is secondary to it's validation
purpose and as such it currently fails both on implied and explicit
behavior.
The ideal solution would be to have FILTER_VALIDATE_BOOLEAN roughly
equal to current behavior with FILTER_NULL_ON_FAILURE and a *seperate*
FILTER_SANITIZE_BOOLEAN similar to current behavior w/o the null failure
flag. This however probably is impossible due to BC.
------------------------------------------------------------------------
[2009-09-10 11:09:43] sjo...@php.net
I agree that filter_var() should return null for the empty string. I
think that this usage of filter_var() is meant to convert string
representations of booleans to boolean values. That is, "true", "on",
"1", "false", "off" and "0" should be converted, other strings should
return null.
------------------------------------------------------------------------
[2009-09-10 09:05:53] m dot kurzyna at crystalpoint dot pl
Personally i think it's just fine (empty string ain't false - if
anything it's null) but in PHP world it is (both on PHP and C levels):
(string)false = ''
(boolean)'' == false
Z_STRLEN_P(value) = 0
Oh, and there is this little documentation thingy you like to cite from
time to time:
If FILTER_NULL_ON_FAILURE is set, FALSE is returned only for "0",
"false", "off", "no", and "", and NULL is returned for all non-boolean
values.
where empty string is explicitly stated as being false.
------------------------------------------------------------------------
[2009-09-10 08:57:29] sjo...@php.net
Why do you think it is wrong that it returns null for an empty string?
------------------------------------------------------------------------
[2009-09-10 08:53:11] m dot kurzyna at crystalpoint dot pl
Actually it is broken even more then i initially reported because it
also returns NULL for empty string:
filter_var('',FILTER_VALIDATE_BOOLEAN,array('flags'=>FILTER_NULL_ON_FAILURE))
// got NULL, expected false
The problem is in ext/filter/logical_filters.c(233) - the check is done
by using string representation of zval being checked. For false value
it's an empty string and the switch from line 244 doesn't cover this
case (hence same result for false and empty string).
Something along the lines of following patch should fix the problem:
--- logical_filters.c 2009-06-10 21:01:17.000000000 +0200
+++ logical_filters.fixed.c 2009-09-10 10:48:59.953675880 +0200
@@ -242,6 +242,10 @@
* returns false for "0", "false", "off", "no", and ""
* null otherwise. */
switch (len) {
+ case 0:
+ ret = 0;
+ break;
+
case 1:
if (*str == '1') {
ret = 1;
On the side note: i was always wondering why (string)false == '' and not
'0'?
------------------------------------------------------------------------
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the rest of the comments, please view the bug report online at
http://bugs.php.net/bug.php?id=49510
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