boolean variables posted through AJAX being treated as strings in server side

Question

Following is a part of an AJAX functionality to add classes and packs to session cart:-

The jquery part

function addClassToCart(itemId) {    addItemToCart(itemId,true); }  function addPackToCart(itemId) {    addItemToCart(itemId,false); }  function addItemToCart(itemId,isClass) {         $.post(url+"/ajax/add_cart", { operation: 'add_cart','isClass':isClass, 'itemId': itemId},         function(data)         {                if(data.success)                {                       alert("item added to cart");                }         }, "json");  } 

The AJAX request processing php part -

//Checking operation and other posted parameters if($_POST['isClass']) {   //Code to add class to session cart  } else {   //Code to add pack to session cart } 

The strange thing

No matter whether I pass true/false (by calling addClassToCart() and addPackToCart()), always the code to add class to session cart executes.
If I put echo statements there like this:-

    if($_POST['isClass'])     {       echo "see if condition ".$_POST['isClass'];     }     else     {       echo "see else condition ".$_POST['isClass'];     } 

This is the output:-

addClassToCart() see if condition true
addPackToCart() see if condition false

Putting conditions like this in the jquery code however works fine:-

function addItemToCart(itemId,isClass)  {        if(isClass)         alert("is class");      else         alert("is pack");  } 

Finally, if I alter the server side code to this:-

if($_POST['isClass'] === true)         {           echo "see if condition ".$_POST['isClass'];         }         else         {           echo "see else condition ".$_POST['isClass'];         } 

These are the outputs -

addClassToCart() see else condition true
addPackToCart() see else condition false

So, why is the boolean variable treated as a string here? Am I doing something wrong in posting parameters?

Thanks, Sandeepan

Answer 1

Also you can use filter_var function with filter FILTER_VALIDATE_BOOLEAN. According to php documentation it

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.

So receiving of POST parameter will look like:

$isClass = filter_var($_POST['isClass'], FILTER_VALIDATE_BOOLEAN); 

Answer 2

You aren't doing anything wrong per se, it's just that when it gets posted, it looks like this:

operation=add_cart&isClass=true&itemId=1234 

PHP can't tell what the data type is because it isn't passed, it's always just a string of POST data, so compare it to "true" to do your checks, like this:

if($_POST['isClass'] === "true") {   //Code to add class to session cart } else {   //Code to add pack to session cart }