get images attached to post

I want to have the ability to use pictures from the media library in a jquery slider on the home page so that it’s easy for someone else to update the pictures without having to hardcode it. I have attached a bunch of photos to a post and tried this

<?php
$image_query = new WP_Query(array('name'=>'slider-images'));
while ( $image_query->have_posts() ) : $image_query->the_post();
    $args = array( 'post_type' => 'attachment', 'numberposts' => -1, 'post_status' => null, 'post_parent' => $post->ID ); 
    $attachments = get_posts($args);
    if ($attachments) {
        foreach ( $attachments as $attachment ) {
            echo '<li>';
            echo '<img src="'.wp_get_attachment_url($attachment->ID).'" />';
            echo '</li>';
        }
    }
endwhile;
wp_reset_postdata();
?>

but it doesn’t display anything. Is there something wrong with my code or is there an easier/better way to group images together rather than put them in a post?

EDIT: If I use the_content() in my $image_query loop it outputs the images like

<p>
    <a href="..." rel="nofollow noreferrer noopener" rel="nofollow noreferrer noopener">
        <img src="..." />
    </a>
</p>

but what I need is something like

<li>
    <a href="..." rel="nofollow noreferrer noopener" rel="nofollow noreferrer noopener">
        <img src="..." />
    </a>
</li>

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

It’s better to use get_children than get_posts. Here is a quick example that will work. This is in the form of a function that is defined in your plugin or in functions.php then use the function as a template tag.

    /**
     * Gets all images attached to a post
     * @return string
     */
    function wpse_get_images() {
        global $post;
        $id = intval( $post->ID );
        $size = 'medium';
        $attachments = get_children( array(
                'post_parent' => $id,
                'post_status' => 'inherit',
                'post_type' => 'attachment',
                'post_mime_type' => 'image',
                'order' => 'ASC',
                'orderby' => 'menu_order'
            ) );
        if ( empty( $attachments ) )
                    return '';

        $output = "n";
    /**
     * Loop through each attachment
     */
    foreach ( $attachments as $id  => $attachment ) :

        $title = esc_html( $attachment->post_title, 1 );
        $img = wp_get_attachment_image_src( $id, $size );

        $output .= '<a class="selector thumb" href="' . esc_url( wp_get_attachment_url( $id ) ) . '" rel="nofollow noreferrer noopener" title="' . esc_attr( $title ) . '">';
        $output .= '<img class="aligncenter" src="' . esc_url( $img[0] ) . '" alt="' . esc_attr( $title ) . '" title="' . esc_attr( $title ) . '" />';
        $output .= '</a>';

    endforeach;

        return $output;
    }

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