ID: 46600
Comment by: matt at mpcm dot com
Reported By: Matt at mpcm dot com
Status: Feedback
Bug Type: JSON related
Operating System: *
PHP Version: 5CVS, 6CVS (2008-11-18)
New Comment:
A note about this in the json_decode page would be appreciated. Perhaps
a strict mode flag, so that it can fail if it cannot be decoded as an
object (?). For the moment the only safe way to decode json is into
arrays.
The _empty_ behavior I thought was a bug (as it was with arrays) is a
required behavior for objects (at least without __get && __set in a
wrapper class).
The bugs that jump out at me now can be seen with the code below... you
can create objects with unreachable properties. If that blank property
access is fixed, then this becomes not so much of an issue. Or it should
be stopped from ever happening... silent errors bite us all.
Illegal Member variable name if var_dump does it, fatal if a user does
it.
Notice: PHPDocument1 line 8 - Illegal member variable name
<?
$blank = '';
$another = ' another';
$a = array($blank=>1234, 'some other key'=>5678, $another=>9999);
$b = (object) $a;
$c = json_decode(json_encode($a));
var_dump($b);
var_dump($c);
#echo $b->$blank; //fatal
echo $b->$another; //works
#echo $c->$blank; //fatal
echo $c->$another; //works
?>
Previous Comments:
------------------------------------------------------------------------
[2008-12-18 03:27:25] scott...@php.net
I'm not even sure what the bug is? You can't have an empty property
name hence the use of "_empty_".
The key collision thing is a very edge case, are you saying you ran
into this in a real life usage?
The best course of action may be to have this documented on the
json_encode() and json_decode() pages.
------------------------------------------------------------------------
[2008-12-04 20:39:13] Matt at mpcm dot com
Thanx for the reply magicaltux, `Feature` is an interesting word
considering the possible key collision.
There are other ways to get things that are not strictly objects to
behave that way. Overloading (like example #1 at
http://us.php.net/manual/en/language.oop5.overloading.php). It works
well enough as long as you also make it iterate correctly.
What I am suggesting is that it is better to fail in decoding into an
object, than to silently cause a key collision.
Or alternatively, produce an overloaded object which can have these
keys (by default, or passed optional flag) from json_decode. It's an
opinion, but a wrapper gets me where I need to be for now, and I'm
pretty sure this is an edge case.
$a = '{"":"a","_empty_":"b"}';
echo json_encode(json_decode($a));
echo json_encode(json_decode($a, true));
output:
{"_empty_":"b"}
{"":"a","_empty_":"b"}
for some values:
$a != json_encode(json_decode($a));
------------------------------------------------------------------------
[2008-12-04 10:44:29] magical...@php.net
I believe this is not a bug, but a feature.
An object *can't* have an empty property (while an array can).
If you want to use json_decode() with json containing empty key, either
access those empty key using special keyword "_empty_", or put the
optionnal $assoc parameter of json_decode() to true to get result as an
array.
If you want objects to support empty keys, I believe this is not going
to happen soon, as this is enforced by a specific error message.
Fatal error: Cannot access empty property in php shell code on line 1
Please note that a property name starting with NULL character won't
work either.
------------------------------------------------------------------------
[2008-11-18 17:35:30] matt at mpcm dot com
The language seems to create a key that cannot be reached, so even if
this `bug` is fixed, we am still facing a broader issue it seems.
<?
$key = "";
$o = (object) array($key=>4,"example"=>8);
var_dump($o);
print 'blank key test:' . (isset($o->$key)?'true':'false');
print $o->{$key};
var_dump($o->$key);
?>
output:
object(stdClass)#1 (2) {
[""]=>
int(4)
["example"]=>
int(8)
}
blank key test:false<br />
<b>Fatal error</b>: Cannot access empty property in
<b>PHPDocument1</b> on line <b>8</b><br />
All throws Notice: line 4 - Illegal member variable name
------------------------------------------------------------------------
[2008-11-18 15:43:05] matt at mpcm dot com
All the work arounds I am looking at are throwing Error Text: Illegal
member variable name when I convert/cast an object with a blank
property.
Is this json_decode `bug` a result of a larger object mechanism
limitation inside of php's object handling?
------------------------------------------------------------------------
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the rest of the comments, please view the bug report online at
http://bugs.php.net/46600
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