Send a boolean value in jQuery ajax data

Question

I'm sending some data in an Ajax call. One of the values is a boolean set to FALSE. It is always evaluated as TRUE in the PHP script called by the Ajax. Any ideas?

$.ajax({
    type: "POST",
    data: {photo_id: photo_id, 
           vote: 1, 
           undo_vote: false},   // This is the important boolean!
    url: "../../build/ajaxes/vote.php",
    success: function(data){
        console.log(data);
    }
}); 

In vote.php, the script that is called in the above Ajax, I check the boolean value:

if ($_POST['undo_vote'] == true) {
    Photo::undo_vote($_POST['photo_id']);
} else {
    Photo::vote($_POST['photo_id'], $_POST['vote']);
}

But the $_POST['undo_vote'] == true condition is ALWAYS met.

Solution 1

A post is just text, and text will evaluate as true in php. A quick fix would be to send a zero instead of false. You could also put quotes around your true in PHP.

if ($_POST['undo_vote'] == "true") {
    Photo::undo_vote($_POST['photo_id']);
} else {
    Photo::vote($_POST['photo_id'], $_POST['vote']);
}

Then you can pass in true/false text. If that's what you prefer.

Solution 2

You can use JSON.stringify() to send request data:

data : JSON.stringify(json)

and decode it on server:

$data = json_decode($_POST);

Solution 3

You can use 0 and 1 for undo_vote and type cast it in php:

JS side:

undo_vote: 0 // false

Server side:

$undovote = (bool) $_POST['undo_vote']; // now you have Boolean true / false

if($undovote) {
    // True, do something 
} else {
   // False, do something else 
}

Comments

[Don P]

Is it bad practice to send booleans as 0 or 1? Should I be doing some JSON encoding, or something else to make the type stronger?

[Don P]

Your answer is correct and works by the way, just need 8 minutes to accept :)

[Markus Schober]

@DonnyP It's really a matter of taste. Most programmers know how 1 and 0 work for true/false, but depending upon where this is being used it may be clearer to use JSON.

[Beetroot-Beetroot]

The traditional (pre-JSON, pre-REST) approach would be to include undo_vote: 1 for true and to exclude undo_vote altogether for false. Then, server-side booleanize $_POST['undo_vote'] depending on whether it's present or not (and optionally interpret '0' and 'false' as false). For something simple like this I might still use that approach today.