$args = array(
'post_type' => 'gallery',
'post_status' => 'publish',
'posts_per_page' => 4, // -1
'order' => 'ASC',
'offset' => 0,
'category' => '',
'orderby' => 'post_date',
'include' => '',
'exclude' => '',
'meta_key' => '',
'meta_value' => '',
'post_type' => 'gallery',
'post_mime_type' => '', // image, video, video/mp4
'post_parent' => '',
);
// sql
$query = new WP_Query;
$myposts = $query->query($args);
// что содержит $myposts
[0] => WP_Post Object
(
[ID] => 69
[post_author] => 1
[post_date] => 2016-03-27 18:06:38
[post_date_gmt] => 2016-03-27 15:06:38
[post_content] =>
[post_title] => first image
[post_excerpt] =>
[post_status] => publish
[comment_status] => closed
[ping_status] => closed
[post_password] =>
[post_name] => first-image
[to_ping] =>
[pinged] =>
[post_modified] => 2016-03-27 18:06:38
[post_modified_gmt] => 2016-03-27 15:06:38
[post_content_filtered] =>
[post_parent] => 0
[guid] => http://newsite2.ru/?post_type=gallery&p=69
[menu_order] => 0
[post_type] => gallery
[post_mime_type] =>
[comment_count] => 0
[filter] => raw