Soluzione:
1) nelle tue funzioni.php , aggiungi il blocco per registrare gli script necessari:
// add necessary scripts
add_action('plugins_loaded', function(){
if($GLOBALS['pagenow']=='post.php'){
add_action('admin_print_scripts', 'my_admin_scripts');
add_action('admin_print_styles', 'my_admin_styles');
}
});
function my_admin_scripts(){
wp_enqueue_script('jquery');
wp_enqueue_script('media-upload');
wp_enqueue_script('thickbox');
}
// Proper way to enqueue
// wp_register_script(
// 'my-upload',
// WP_PLUGIN_URL.'/my-script.js',
// array('jquery','media-upload','thickbox') /* dependencies */
// );
//
// wp_enqueue_script('my-upload');
function my_admin_styles(){
wp_enqueue_style('thickbox');
}
2) e quindi aggiungere il blocco metabox :
add_action(
'add_meta_boxes',
function(){
add_meta_box(
'my-metaboxx1', // ID
'my-metaboxx1-title', // Title
'func99999', // Callback (Construct function)
get_post_types(), //screen (This adds metabox to all post types)
'normal' // Context
);
},
9
);
function func99999($post){
$url = get_post_meta($post->ID, 'my-image-for-post', true); ?>
<input id="my_image_URL" name="my_image_URL" type="text"
value="<?php echo $url;?>" style="width:400px;" />
<input id="my_upl_button" type="button" value="Upload Image" /><br/>
<img src="<?php echo $url;?>" style="width:200px;" id="picsrc" />
<script>
jQuery(document).ready( function($) {
jQuery('#my_upl_button').click(function() {
window.send_to_editor = function(html) {
imgurl = jQuery(html).attr('src')
jQuery('#my_image_URL').val(imgurl);
jQuery('#picsrc').attr("src", imgurl);
tb_remove();
}
formfield = jQuery('#my_image_URL').attr('name');
tb_show('', 'media-upload.php?type=image&TB_iframe=true' );
return false;
}); // End on click
});
</script>
<?php
}
add_action('save_post', function ($post_id) {
if (isset($_POST['my_image_URL'])){
update_post_meta($post_id, 'my-image-for-post', $_POST['my_image_URL']);
}
});
ps nel caso in cui siano necessari più campi, quindi puoi farlo facilmente in questo modo: http://pastebin.com/raw/xpU1ch2W