How can I json_encode the output of my function?

Question

How can I json_encode the output of this function I use to get all attached images of a post?

<?php
function get_all_images($postid=0, $size='bigger', $attributes='') {
    if ($postid<1) $postid = get_the_ID();
    if ($images = get_children(array(
        'post_parent' => $postid,
        'post_type' => 'attachment',
        'numberposts' => -1,
        'orderby' => 'menu_order',
        'post_mime_type' => 'image',)))
        foreach($images as $image) {
            $attachment=wp_get_attachment_image_src($image->ID, $size);
            ?><img src="<?php echo $attachment[0]; ?>" alt="" /><?php
        }
}?>

Everything is already setup for admin-ajax.php.

Answer 1

Not sure if the get_all_images() function is the one that is added to your wp_ajax_{action} hook. If it is you will want to output a string back to your js. I would define a variable and concatenate the img html to it as you loop through your images.

function get_all_images() {
//your code
$response = '';
foreach($images as $image) {
        $attachment=wp_get_attachment_image_src($image->ID, $size);

        $response .= '<img src="'.$attachment[0].'" alt="" />';
    }

 die( json_encode( $response ) );

}