Passing a boolean through PHP GET

Question

Pretty simple question here, not sure the answer though. Can I pass a boolean variable through get? For example:

http://example.com/foo.php?myVar=true

then I have

$hopefullyBool = $_GET['myVar'];

Is $hopefullyBool a boolean or a string? My hypothesis is that it's a string but can someone let me know? Thanks

Use `myVar=1` or `myVar=0` instead. Then you can easily convert to booean in your PHP script. — Jonathan M, Jun 05 '14 at 15:02
Try: [how-to-convert-string-to-boolean-php](http://stackoverflow.com/questions/7336861/how-to-convert-string-to-boolean-php) — txc03u, Jun 05 '14 at 15:02

AbraCadaver · Accepted Answer · 2020-08-06T16:36:58.653

47

All GET parameters will be strings (or an array of strings) in PHP. Use filter_var (or filter_input) and FILTER_VALIDATE_BOOLEAN:

Returns TRUE for "1", "true", "on" and "yes". Returns FALSE otherwise.

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.

$hopefullyBool = filter_var($_GET['myVar'], FILTER_VALIDATE_BOOLEAN);

For INPUT vars that can be arrays there is filter_var_array and filter_input_array.

Another way to get the type boolean, pass something that evaluates to true or false like 0 or 1:

http://example.com/foo.php?myVar=0
http://example.com/foo.php?myVar=1

Then cast to boolean:

$hopefullyBool = (bool)$_GET['myVar'];

If you want to pass string true or false then another way:

$hopefullyBool = $_GET['myVar'] == 'true' ? true : false;

But I would say that filter_var with FILTER_VALIDATE_BOOLEAN was meant for this.

edited Aug 06 '20 at 16:36

answered Jun 05 '14 at 14:59

AbraCadaver

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Is there any difference in this one and "$hopefullyBool = 'true' === $_GET['myVar'];" ? – Agash Thamo. Jun 20 '14 at 14:25
K, thanks, so it should be the same then. I was worried that I used the wrong way. – Agash Thamo. Jun 23 '14 at 11:28
(bool) would convert "false" to true – John Mar 07 '18 at 22:20
@John: Yes, that's why my example for `(bool)` uses 0 and 1 not "true" and "false". – AbraCadaver Mar 08 '18 at 18:20
There is an exception: `http://example.com/foo.php?myVar[]=0` `http://example.com/foo.php?myVar[]=1` Here `myVar` param will be _array_ in PHP. – Oct 11 '19 at 05:37
@DanAlexson90: That's why there is https://www.php.net/manual/en/function.filter-var-array.php – AbraCadaver Oct 11 '19 at 11:37
@AbraCadaver, that's a comment regarding "_All_ GET parameters will be strings in PHP." – Oct 12 '19 at 06:57

score 5 · Answer 2 · edited Oct 02 '17 at 19:45

5

If you want to avoid an if statement:

filter_var('true', FILTER_VALIDATE_BOOLEAN);  
//bool(true)

filter_var('false', FILTER_VALIDATE_BOOLEAN); 
//bool(false)

edited Oct 02 '17 at 19:45

AbraCadaver

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answered Jan 17 '17 at 19:09

Roman

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score 3 · Answer 3 · answered Jun 05 '14 at 15:01

It would be passed as a string. While you can convert it using the bool cast, it is recommended to not do so in some cases.

You would be better off doing if myVar == "True"

Be cautious:

>>> bool("foo")
True
>>> bool("")
False

Empty strings evaluate to False, but everything else evaluates to True. So this should not be used for any kind of parsing purposes.

score 2 · Answer 4 · answered Mar 25 '19 at 13:46

There's a few ways to do it. Firstly we could use PHP's in-built (boolean) method, which casts a string value to a boolean:

$hopefullyBool = (boolean)$_GET['myVar'];

This would result in a boolean value of true or false depending on the value of the string in $_GET['myVar'].

From v5.2.1 upwards, we can also use json_decode() to ascertain the boolean value:

$hopefullyBool = json_decode($_GET['myVar]);

The json_decode() method parses a JSON Object (which is a string) into a PHP variable, and takes type-casting into account. As a result, the string 'true' from the URL param will be cast to the boolean true.

You could use both of the above methods in tandem, using:

$hopefullyBool = (boolean)json_decode($_GET['myVar]);

To mitigate against uppercase characters being passed in the URL param (eg ?myVar=True or ?myVar=FALSE), you should use the strtolower() method, which will convert a string to all lowercase letters:

$hopefullyBool = (boolean)json_decode(strtolower($_GET['myVar]));

Finally, we'll want to fall-back to false if the parameter is not present in the URL's query string, otherwise PHP will throw an Undefined Index notice. To do this, we can use the isset() method:

$hopefullyBool = false;
if ( isset($_GET['myVar']) ) {
    $hopefullyBool = (boolean)json_decode(strtolower($_GET['myVar]));
}

To shorten this, you could initiate $hopefullyBool using a conditional statement like so:

$hopefullyBool = isset($_GET['myVar']) && (boolean)json_decode(strtolower($_GET['myVar']));

score 0 · Answer 5 · answered May 18 '21 at 21:28

0

if I'm sure that the only thing being passed is a boolean, I normally just check if it's equal to String "true" if it is, then it return true, if not then it return false

$is_true= $_GET['is_true'] == "true";

answered May 18 '21 at 21:28

grom

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Passing a boolean through PHP GET

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