How can I convert PHP objects to JSON before PHP 5.4?

Converting PHP Objects to JSON Before PHP 5.4

While PHP 5.4 introduced the convenient JsonSerializable interface for simplifying object-to-JSON conversion, this option is not available for PHP versions below 5.4. To achieve similar functionality in earlier versions, consider the following approaches:

Method 1: Type Casting and Array Casting

For simple objects, type casting the object to an array and then encoding the resulting array can suffice:

<code class="php">$json = json_encode((array)$object);</code>

Method 2: Recursive toArray Method

Create a toArray() method in your object class to recursively convert its properties to an array. If the properties are themselves objects, recursively call toArray() on them as well:

<code class="php">public function toArray()
{
    $array = (array) $this;
    array_walk_recursive($array, function (&$property) {
        if ($property instanceof Mf_Data) {
            $property = $property->toArray();
        }
    });
    return $array;
}</code>

By removing circular references (e.g., _parent) from the array, you can avoid recursion-related issues:

<code class="php">public function toArray()
{
    $array = get_object_vars($this);
    unset($array['_parent'], $array['_index']);
    array_walk_recursive($array, function (&$property) {
        if (is_object($property) && method_exists($property, 'toArray')) {
            $property = $property->toArray();
        }
    });
    return $array;
}</code>

Method 3: Interface-Based Conversion

Define an interface (e.g., ToMapInterface) that includes methods for converting an object to an array (toMap()) and getting a subset of properties to include in the conversion (getToMapProperties()):

<code class="php">interface ToMapInterface
{
    function toMap();

    function getToMapProperties();
}</code>

In your Node class, implement these methods to create a more structured and testable conversion process:

<code class="php">class Node implements ToMapInterface
{
    public function toMap()
    {
        $array = $this->getToMapProperties();
        array_walk_recursive($array, function (&$value) {
            if ($value instanceof ToMapInterface) {
                $value = $value->toMap();
            }
        });
        return $array;
    }

    public function getToMapProperties()
    {
        return array_diff_key(get_object_vars($this), array_flip(array(
            'index', 'parent'
        )));
    }
}</code>

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