Sol let's suppose that we send a post query to a PHP file,
this query where we have ...&title=title
where title is for example title=$(#title).val(); (assuming we're including Jquery)
in PHP we have $title=$_POST['title'];
Let's suppose then that title is null , will PHP consider null as string ? or something empty ?
4 Answers
From the PHP Manual:
The special NULL value represents a variable with no value. NULL is the only possible value of type NULL.
A variable is considered to be NULL if:
- it has been assigned the constant
NULL. - it has not been set to any value yet.
- it has been unset().
"NULL" is not the same as NULL.
var_dump("null" == NULL);
Outputs:
bool(false)
6 Comments
Aymane Shuichi
But the thing is this null value is sent from Javascript , it's like title=null then you do a $title=$_POST['title']; which basically gives $title="null"; doesn't it ?
Martijn
that is will be like this:
$variable = "null";, null as a string
Amal
@AymaneShuichi: See the answer.
"NULL" is not the same as NULLAmal
@Downvoter: can you suggest any improvements / explain the downvote?
mewm
It would not evaluate to the type NULL, but more a string containing 'null', but in this case, the argument is most likely parsed, but with no value.
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The title gets converted to a string before sending it to the server.
Converting the JS value null to a string results in a string "null". Therefore, PHP will only interpret the variable as a string.
However, I doubt that you will receive a null value from an empty input box. You will get an empty string instead.
1 Comment
mewm
$(#title).val(); will probably not evaluate to 'null' unless the element doesn't exist.In your case, if you send a $(#title).val(); as data in an ajax request to a php script, and the input is empty, it would just be an empty string.
1 Comment
Aymane Shuichi
what if it returns undefined in Javascript ? will $title get the string "undefined" ?
php intercepts js null as "null" -> string, So to handle form request, i had small work around in my php code like below
function checknull($arg){
if($arg == "null"){
return;
}else{
return $arg;
}
}
$a=array();
$b = "null";
$a['hi'] = checknull($b);
var_dump($a);
This will output as
array(1) { ["hi"]=> NULL }
//same you can test it for $_REQUEST
$var1 = checknull($_POST['title']);
var_dump($var1);
or you can use
$var1 = $_POST['title'] === 'null'? NULL : $_POST['title'];
var_dump($var1);
NULL. Trying to set it with any other null-like value will result in an empty stringtitlewon't be null,val()always returns a string (assuming you've selected an input)