Posting JSON with jquery ajax to PHP

Question

I have a simple php file that decode my json string, passed with ajax, and stamp the result, but I can't keep the $_POST variable, why???

I try to inspect with fireBug and I can see that the POST request is sent correctly, when the php script is called, he respond Noooooooob to me, it seem any POST variable is set.

All I want is to have my array =)

JSON String generated by JSON.stringify:

[
   {
      "id":21,
      "children":[
         {
            "id":196
         },
         {
            "id":195
         },
         {
            "id":49
         },
         {
            "id":194
         }
      ]
   },
   {
      "id":29,
      "children":[
         {
            "id":184
         },
         {
            "id":152
         }
      ]
   },
   ...
]

JavaScript

$('#save').click(function() {
  var tmp = JSON.stringify($('.dd').nestable('serialize'));
  // tmp value: [{"id":21,"children":[{"id":196},{"id":195},{"id":49},{"id":194}]},{"id":29,"children":[{"id":184},{"id":152}]},...]
  $.ajax({
    type: 'POST',
    url: 'save_categories.php',
    dataType: 'json',
    data: {'categories': tmp},
    success: function(msg) {
      alert(msg);
    }
  });
});

save_categories.php

<?php
  if(isset($_POST['categories'])) {
    $json = $_POST['categories'];
    var_dump(json_decode($json, true));
  } else {
    echo "Noooooooob";
  }
?>

Answer 1

Your code works if you remove dataType: 'json', just tested it.

$('#save').click(function() {
  var tmp = JSON.stringify($('.dd').nestable('serialize'));
  // tmp value: [{"id":21,"children":[{"id":196},{"id":195},{"id":49},{"id":194}]},{"id":29,"children":[{"id":184},{"id":152}]},...]
  $.ajax({
    type: 'POST',
    url: 'save_categories.php',
    data: {'categories': tmp},
    success: function(msg) {
      alert(msg);
    }
  });
});