The PHP script encountered an issue when trying to pass a MySQL request through to the getJSON() function

Seeking guidance from an expert on the following enigma.

In my HTML, I utilized getJSON().

When using a hardcoded array that can be json_encoded (by setting $DEBUG = true), the data is passed to JavaScript for browser display successfully. However, encountering failure when attempting to generate dynamic array text from MySQL (by setting $DEBUG = false).

I am puzzled on how to make the dynamically generated MySQL array work. Both scenarios can be tested with JSON formatted output in the browser at http://www.example.com/phpTWLLT/json_encoded_array.php.

If $DEBUG is set to true,

The output displayed in the browser from localhost/phpTWLLT/json_encode_array.php:

[{"active":"0","first_name":"Darian","last_name":"Brown","age":"28","email":"[email protected]"},{"active":"1","first_name":"John","last_name":"Doe","age":"47","email":"[email protected]"}]

The list will be shown in the browser as: 0, 1

If $DEBUG is set to false,

The output displayed in the browser from localhost/phpTWLLT/json_encode_array.php:

[{"active":"1"},{"active":"1"}]

The browser will show a blank display.

HTML file:

<!DOCTYPE html>
<html>
    <head>
        <script type='text/javascript' src='js/jquery.min.js'></script>

        <meta charset="UTF-8">
    </head>    
    <body>

        <ul></ul>

        <script type='text/javascript'>
            $(document).ready(function () {
                $.getJSON('json_encoded_array.php', function (data) {

                    $.each(data, function (key, val) {
                        $('ul').append('<li id="' + key + '">' + val.active  + '</li>');
                    });
                });
            });
        </script>

    </body>
</html>

PHP script: json_encoded_array.php

<?php

$DEBUG = true;

if ($DEBUG) {
    // Array data for debugging
} else {
    // PHP script for querying MySQL database
}
echo json_encode($arr);
?>

Answer №1

To output data as JSON in a PHP script called json_encoded_array.php, you must include a header with the following code:

 header("Content-type: application/json");

By default, PHP will return text/html content type, which is not compatible with $.getJSON() function for JSON.

The correct MIME media type for JSON text is application/json and the default encoding is UTF-8 (Source: RFC 4627).

Answer №2

The jQuery function <strong>$.each</strong> is used to iterate through a JavaScript array or object, not a JSON string. To work with a JSON string, you first need to parse it using the <strong>jQuery.parseJSON()</strong> method.

Here's an example of how you can achieve this:

data = jQuery.parseJSON(data);

    $.each(data, function (key, val) {
        $('ul').append('<li id="' + key + '">' + val.active  + '</li>');
    });

Answer №3

Discovered that the default License Header generated by Netbeans was causing issues with Javascript recognizing the JSON structure.

By removing the default License Header and making it blank, the output from the PHP script now only contains the JSON structure, and the browser displays correctly.

For comparison, please view the two debug outputs below (images cannot be posted): debugFalse4.jpg: debugFalseWrking.jpg:

A big thank you to Saquieb for showing how to access the debug information!!!

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