How to call Shortcode categories for custom post types?

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Hi I’m trying to do something rather tricky in my WordPress Theme I’m more of a designer front-end developer so its a bit of a guess work with php. Anyone have any ideas why this code only displays one slide. I want it to run a slideshow pulling in multipe slides from one category in my theme.

Thanks For your help

    //Add Nivo Short Codes
function nivo_slider_function($atts){

   extract(shortcode_atts(array(
      'posts' => 5,
      'category' => ''
   ), $atts));

 $args = array(
        'numberposts' => -1,
        'orderby' => 'menu_order',
        'order' => 'ASC',
        'post_type' => 'homepage_slider'
    );

    if ( ! empty( $category ) ) {
        $args['category_name'] = $category;
    }

    $posts = get_posts( $args );

    $homepage_slider  = '<div id="slider">'; //Open the container
    foreach ( $posts as $post ) { // Generate the markup for each Question
        $homepage_slider .= sprintf(('<h3><a href="">%1$s</a></h3><div>%2$s</div>'),
            $post->post_title,
            wpautop($post->post_content)
        );
    }
    $homepage_slider .= '</div>'; //Close the container


   $return_string = '<div id="slider" class="nivoSlider">';

   query_posts(array('post_type' => 'homepage_slider', 'orderby' => 'menu_order', 'order' => 'ASC' , 'showposts' => $posts));

   if (have_posts()) :
      while (have_posts()) : the_post();

         $slider_img_src = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), 'homepage-slide', false);
         $target_link = get_post_meta(get_the_ID(), 'slide_target_link', true);   
         $return_string .= '<a href="'.$target_link.'" rel="nofollow"><img src="' . $slider_img_src[0] .'" /></a>';

      endwhile;
   endif;
   $return_string .= '</div>';

   wp_reset_query();
   return $return_string;

}

function register_shortcodes(){
   add_shortcode('slider-demo', 'nivo_slider_function');
}

add_action( 'init', 'register_shortcodes');

This was the original code taken from a comment on this page. After following the slider tutorial I wanted to use the a shortcode to post it on any page instead of a template however I also wanted different slideshows so was trying above to add in the ability to connect the slideshows with categories.

http://willrees.com/2013/05/create-and-manage-a-nivo-slider-using-wordpress-custom-post-types/

function nivo_slider_function($atts){

   extract(shortcode_atts(array(
      'posts' => 5,
   ), $atts));

   $return_string = '<div id="slider" class="nivoSlider">';

   query_posts(array('post_type' => 'homepage_slider', 'orderby' => 'menu_order', 'order' => 'ASC' , 'showposts' => $posts));

   if (have_posts()) :
      while (have_posts()) : the_post();

         $slider_img_src = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), 'homepage-slide', false);
     $target_link = get_post_meta(get_the_ID(), 'slide_target_link', true);

         $return_string .= '<a href="'.$target_link.'" rel="nofollow"><img src="' . $slider_img_src[0] .'" /></a>';

      endwhile;
   endif;
   $return_string .= '</div>';

   wp_reset_query();
   return $return_string;
}

function register_shortcodes(){
   add_shortcode('slider-demo', 'nivo_slider_function');
}

add_action( 'init', 'register_shortcodes');

Answer

What surprise me is that someone on May 2013, write a tutorial using extract and query_posts in same function.

extract is considered a bad practice in PHP in general, and it’s usage was abandoned also from WP core (it will no longer be used, but there are still extract calls in actual code).

query_posts is a bad practice in WordPress world, you can read about it in the most famous WPSE answer by Rarst and in Codex too (that actually use the picture by Rarst).

Also:

  1. your code use the deprecarted argument ‘numposts’, use ‘posts_per_page’ instead
  2. your code put stuff in html output without escaping with esc_* functions
  3. your code output images without alt attribute that is required for W3C compliant html code

That said, what you want to do is simple a matter of a new WP_Query called from shortcode callback.

function nivo_slider_function( $atts ){

   $posts_per_page = isset( $atts['posts'] ) ? $atts['posts'] : -1;

   $args = array(
     'posts_per_page' => $posts_per_page,
     'orderby' => 'menu_order',
     'order' => 'ASC',
     'post_type' => 'homepage_slider'
   );

   if ( isset($atts['category']) && ! empty( $atts['category'] ) ) {
     $args['category_name'] = $atts['category'];
   }

   $query = new WP_Query( $args );

   // nothing to do if we have no posts
   if ( ! $query->have_posts() ) return;

   $slide_format = '<a href="%s" rel="nofollow"><img src="%s" alt="" /></a>';
   $slides = '';
   $slider = '';

   while( $query->have_posts() ) { $query->the_post();
     $thumbid = get_post_thumbnail_id($post->ID);
     // if post has not thumbnail return
     if ( empty( $thumbid ) ) continue;
     $img_src = (array) wp_get_attachment_image_src( $thumbid, 'homepage-slide' );
     // if a valid image is not foud return
     if ( empty( $img_src ) || ! filter_var( $img_src[0], FILTER_VALIDATE_URL ) ) continue;
     $target_link = get_post_meta( get_the_ID(), 'slide_target_link', true );
     // if no valid link is saved in 'slide_target_link' meta, set link to '#'
     if (empty( $target_link ) || ! filter_var( $target_link, FILTER_VALIDATE_URL ) ) {
       $target_link = '#';
     }
     $slides .= sprintf( $slide_format, esc_url( $target_link ), esc_url( $img_src[0] ) );
   }

   wp_reset_postdata();

   if ( ! empty( $slides ) ) {
     $id = esc_attr( wp_generate_password( 6, false, false) );
     $slider = "<div id=\"slider_{$id}\" class=\"nivoSlider\">{$slides}</div>";
   }

   return $slider;
}

Attribution
Source : Link , Question Author : brightmist.co.uk , Answer Author : Community

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