DataTable - Invalid JSON response when retrieved from PHP

Question

I know that it's a common question, but I have a different problem.

• When I retrieve a Json response from PHP, it throws this alert warning and don't load the data into the datatable.
• When I load the generated Json (retrieved from PHP) directly from file, the datatable loads the data correctly.

I have the following jquery configuration for my datatable:

$( document ).ready(function() {
$('#example').dataTable({
        "language": {
            "url": "//cdn.datatables.net/plug-ins/9dcbecd42ad/i18n/Spanish.json"
        },
        "bProcessing": true,
               "sAjaxSource": "response.php",
        "aoColumns": [
              { mData: 'id' } ,
              { mData: 'name' },
              { mData: 'description' }
              //{ mData: 'img', render: getImg },
        ]
      });
});

The generated json from php (that works if loaded directly from file):

{
    "sEcho": 1,
    "iTotalRecords": 10,
    "iTotalDisplayRecords": 10,
    "aaData": [{
        "id": "1",
        "name": "Salsa estilo Casino",
        "description": "Descri\u00e7\u00e3o ..."
    }, {
        "id": "2",
        "name": "Salsa estilo Son",
        "description": "Descri\u00e7\u00e3o ..."
    }, {
        "id": "3",
        "name": "Salsa LA",
        "description": "Descri\u00e7\u00e3o ..."
    }, {
        "id": "4",
        "name": "Salsa NY",
        "description": "Descri\u00e7\u00e3o ..."
    }, {
        "id": "5",
        "name": "Bachata",
        "description": "Descri\u00e7\u00e3o ..."
    }, {
        "id": "6",
        "name": "Reggaeton",
        "description": "Descri\u00e7\u00e3o ..."
    }, {
        "id": "7",
        "name": "Chachacha",
        "description": "Descri\u00e7\u00e3o ..."
    }, {
        "id": "8",
        "name": "Rumba",
        "description": "Descri\u00e7\u00e3o ..."
    }, {
        "id": "9",
        "name": "Pachanga",
        "description": "Descri\u00e7\u00e3o ..."
    }, {
        "id": "10",
        "name": "Ritmos tradicionais cubanos",
        "description": "Descri\u00e7\u00e3o ..."
    }]
}

My PHP response.php file:

<?php
// my database classe with CRUDed POJOs.
include_once '../admin/db.php';

// That was from a sample code that worked fine.
$data = array(
array('Name'=>'Descrição ...', 'Empid'=>11, 'Salary'=>101, 'img' => '../img/lais.jpg'),
array('Name'=>'alam', 'Empid'=>1, 'Salary'=>102, 'img' => '../img/lais.jpg'),
array('Name'=>'phpflow', 'Empid'=>21, 'Salary'=>103, 'img' => '../img/lais.jpg')                            
);

/* Query the database and retrive in $data2[0] the total number of rows 
and $data2[1] an array of arrays with  the following format (as described above):
array(
    array('id' => '1', 'name' => 'name', 'description' => 'Desc ...'),
    ...
)
*/
$data2 = Turma::fetchAllAssoc();  
$results = array(
        "sEcho" => 1,
    "iTotalRecords" => 10,
    "iTotalDisplayRecords" => 10,
      "aaData"=>$data2[1]);

header('Content-Type: application/json');
echo json_encode($results);

?>

What am I doing wrong? It seems a bug form me.

Answer 1

Solved my problem.

In PHP, the response.php was returning only the json content that was shwon in the browser.

The error was: there was some html commented content that seems hidden in `include_once '../admin/db.php';, even the commented html tags.

When I added the line header('Content-Type: application/json'); everything that seems missing was shown in the browser.

Erased everything, even commented html tags to output (echo) only json_encode($results); . Then, everything worked smoothy.