Getting Featured Image as a Background Image - php

Question

I have a code in my page.php file that creates a list of child pages. I want every li to have a background-image added by Featured image function. Here is the entire code I have
<?php while ( have_posts() ) : the_post(); ?>
<?php get_template_part( 'content', 'page' ); ?>
<?php endwhile; // end of the loop. ?>
<?php
if (is_page('eventsphotography')) {
$query = new WP_query('pagename=eventsphotography');
$eventsphotography_id = $query->queried_object->ID;
//The loop
if($query->have_posts() ) {
while($query->have_posts() ) {
$query->the_post();
the_content();
}
}
/* Get the children of the eventsphotography page */
$args = array (
'post_parent' => $thePostID,
'post_parent' => $eventsphotography_id,
'order' => 'ASC'
);
$eventsphotography_query = new WP_query($args);
//The Loop
if($eventsphotography_query->have_posts() ) {
echo '<ul class="events-list">';
while($eventsphotography_query->have_posts() ){
$eventsphotography_query->the_post();
$background = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'full' );
echo '<li style="background:url(' . $background[0] . '); background-repeat:no-repeat; background-size:cover;">';
echo '<div class="events-centered">';
echo '<a href="' . get_permalink() . '">';
echo '<h4>' . get_the_title() . '</h4>';
echo '</a>';
echo '<div class="view-events-details">';
echo '<a href="' . get_permalink() . '">';
echo '<h5>View Images</h5>';
echo '</a>';
echo '</div>';
echo '</div>'; /* end of events-centered */
echo '</li>';
}
echo'</ul>';
}
}
?>
I only need help for these lines:
$background = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'full' );
AND
echo '<li style="background:url(' . $background[0] . '); background-repeat:no-repeat; background-size:cover;">';
Here's the screenshot of the result of my code:
http://oi68.tinypic.com/10xzdhl.jpg
I marked the first <li> with a red rectangle. As I said before, I want URL of the featured image to be placed in <li style="background:url(URL of the featured image)">

Answer 1

I have found a solution. First, I created a new WP_Query:
$subs = new WP_Query( array( 'post_parent' => $post->ID, 'post_type' => 'page', 'meta_key' => '_thumbnail_id'));
Then in my loop I added this lines:
if($eventsphotography_query->have_posts() && $subs->have_posts()) {
echo '<ul class="events-list">';
while($eventsphotography_query->have_posts() && $subs->have_posts()){
$eventsphotography_query->the_post();
$subs->the_post();
echo '<li>';
echo get_the_post_thumbnail($post->ID);
...rest of the code...