Query custom posts from custom taxonomy

Question

I'm trying to do a custo slideshow, but I have problems with query the posts. I have defined a custom post type "slider" and a custom taxonomy "slideshow":

• custom post type:

  function wms_slider_init() {
  $labels = array(
  'name' => 'Slider',
  'singular_name' => 'Slider',
  'add_new' => 'Add Slider',
  'add_new_item' => 'Add New Slider',
  'edit_item' => 'Edit Slider',
  'new_item' => 'New Slider',
  'all_items' => 'All Sliders',
  'view_item' => 'View Slider',
  'search_items' => 'Search Sliders',
  'not_found' =>  'No Slider found',
  'not_found_in_trash' => 'No Slider found in Trash', 
  'parent_item_colon' => '',
  'menu_name' => 'Sliders'
    );
  
    $args = array(
  'labels' => $labels,
  'description'   => 'Holds our Slider poste specific data',
  'public' => true,
  'publicly_queryable' => true,
  'show_ui' => true, 
  'show_in_menu' => true, 
  'query_var' => true,
  'rewrite' => array( 'slug' => 'slider' ),
  'capability_type' => 'post',
  'has_archive' => false, 
  'hierarchical' => true,
  'menu_position' => 5,
  'supports' => array( 'title', 'editor', 'thumbnail', 'page-attributes')
    ); 
  
    register_post_type( 'slider', $args );
  }
  add_action( 'init', 'wms_slider_init' );
  

• custom taxonomy:

  add_action( 'init', 'wms_create_slider_taxonomies', 0 );
  
  //create SlideShow Category for the post type "slider"
  function wms_create_slider_taxonomies() 
  {
  // Add new taxonomy, make it hierarchical (like categories)
  $labels = array(
  'name'                => _x( 'SlideShows', 'taxonomy general name' ),
  'singular_name'       => _x( 'SlideShow', 'taxonomy singular name' ),
  'search_items'        => __( 'Search Genres' ),
  'all_items'           => __( 'All SlideShows' ),
  'parent_item'         => __( 'Parent SlideShow' ),
  'parent_item_colon'   => __( 'Parent SlideShow:' ),
  'edit_item'           => __( 'Edit SlideShow' ), 
  'update_item'         => __( 'Update SlideShow' ),
  'add_new_item'        => __( 'Add New SlideShow' ),
  'new_item_name'       => __( 'New SlideShow Name' ),
  'menu_name'           => __( 'SlideShow' )
    );    
  
    $args = array(
  'hierarchical'        => true,
  'labels'              => $labels,
  'show_ui'             => true,
  'show_admin_column'   => true,
  'query_var'           => true,
  'rewrite'             => array( 'slug' => 'slideshow' )
   );
  
    register_taxonomy( 'slideshow', array( 'slider' ), $args );
  }
  

I made under taxonomy "slideshow" a "category" named - "homeslide" and I put in it a "slider" named "test". I try to set up a query to retrieve all posts from "homeslide", but the query is not working.

here is my query and response

function wms_output_home_slides($cat) { // $cat = 'homeslide'
  $home_slides_args = array(
            'post_type' => 'slider',
            'posts_per_page'  => -1,
            'tax_query' => array(
            array(
                'taxonomy' => 'slideshow',
                'field' => 'slug',
                'terms' => $cat
                   )
                 )
);
$sliders_query = new WP_Query( $home_slides_args );
//$print_out = '<pre>'.print_r($home_slides_args, true).'</pre>';
//loop
if ($sliders_query->have_posts()) : 
    $print_out .= '<div id="pageBackground">';
    while  ($sliders_query->have_posts()) : $sliders_query->the_post();
        $slider_id          = $post->ID;

        $print_out .= '<div class="one-slide">';

            $print_out .= $slider_id;

        $print_out .= '</div><!-- one-slide -->';
    endwhile;
    $print_out .= '</div><!-- #pageBackground -->';
endif;


return $print_out;
}

Any Ideea why didn't get the post ID?

Answer 1

You should access global variables in php using global keyword.It makes variable( or object, array) visible inside current function we are dealing with. In function wms_output_home_slides you are using $post global variable directly instead access it using global keyword as following.

function wms_output_home_slides($cat) { // $cat = 'homeslide'
global $post;
// You Code Goes here
}

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