underscores Featured Image – brak w php

Dziękuję bardzo za Odpowiedź i poświęcony czas, próbowałem już podobnej procedury, jednak bez skutku, po zastosowaniu Pana metody/sugestii, mam następujący błąd:

Fatal error: Can’t use function return value in write context in …/beta/wp-content/themes/underscores/functions.php on line 145

moje pliki:

[FUNCIONS.PHP]

<?php
/**
 * underscores functions and definitions.
 *
 * @link https://developer.wordpress.org/themes/basics/theme-functions/
 *
 * @package underscores
 */

if ( ! function_exists( 'underscores_setup' ) ) :
/**
 * Sets up theme defaults and registers support for various WordPress features.
 *
 * Note that this function is hooked into the after_setup_theme hook, which
 * runs before the init hook. The init hook is too late for some features, such
 * as indicating support for post thumbnails.
 */
function underscores_setup() {
	/*
	 * Make theme available for translation.
	 * Translations can be filed in the /languages/ directory.
	 * If you're building a theme based on underscores, use a find and replace
	 * to change 'underscores' to the name of your theme in all the template files.
	 */
	load_theme_textdomain( 'underscores', get_template_directory() . '/languages' );

	// Add default posts and comments RSS feed links to head.
	add_theme_support( 'automatic-feed-links' );

	/*
	 * Let WordPress manage the document title.
	 * By adding theme support, we declare that this theme does not use a
	 * hard-coded <title> tag in the document head, and expect WordPress to
	 * provide it for us.
	 */
	add_theme_support( 'title-tag' );

	/*
	 * Enable support for Post Thumbnails on posts and pages.
	 *
	 * @link https://developer.wordpress.org/themes/functionality/featured-images-post-thumbnails/
	 */
	add_theme_support( 'post-thumbnails' );

	// This theme uses wp_nav_menu() in one location.
	register_nav_menus( array(
		'primary' => esc_html__( 'Primary', 'underscores' ),
	) );

	/*
	 * Switch default core markup for search form, comment form, and comments
	 * to output valid HTML5.
	 */
	add_theme_support( 'html5', array(
		'search-form',
		'comment-form',
		'comment-list',
		'gallery',
		'caption',
	) );

	// Set up the WordPress core custom background feature.
	add_theme_support( 'custom-background', apply_filters( 'underscores_custom_background_args', array(
		'default-color' => 'ffffff',
		'default-image' => '',
	) ) );
}
endif;
add_action( 'after_setup_theme', 'underscores_setup' );

/**
 * Set the content width in pixels, based on the theme's design and stylesheet.
 *
 * Priority 0 to make it available to lower priority callbacks.
 *
 * @global int $content_width
 */
function underscores_content_width() {
	$GLOBALS['content_width'] = apply_filters( 'underscores_content_width', 640 );
}
add_action( 'after_setup_theme', 'underscores_content_width', 0 );

/**
 * Register widget area.
 *
 * @link https://developer.wordpress.org/themes/functionality/sidebars/#registering-a-sidebar
 */
function underscores_widgets_init() {
	register_sidebar( array(
		'name'          => esc_html__( 'Sidebar', 'underscores' ),
		'id'            => 'sidebar-1',
		'description'   => esc_html__( 'Add widgets here.', 'underscores' ),
		'before_widget' => '<section id="%1$s" class="widget %2$s">',
		'after_widget'  => '</section>',
		'before_title'  => '<h2 class="widget-title">',
		'after_title'   => '</h2>',
	) );
}
add_action( 'widgets_init', 'underscores_widgets_init' );

/**
 * Enqueue scripts and styles.
 */
function underscores_scripts() {
	wp_enqueue_style( 'underscores-style', get_stylesheet_uri() );

	wp_enqueue_script( 'underscores-navigation', get_template_directory_uri() . '/js/navigation.js', array(), '20151215', true );

	wp_enqueue_script( 'underscores-skip-link-focus-fix', get_template_directory_uri() . '/js/skip-link-focus-fix.js', array(), '20151215', true );

	if ( is_singular() && comments_open() && get_option( 'thread_comments' ) ) {
		wp_enqueue_script( 'comment-reply' );
	}
}
add_action( 'wp_enqueue_scripts', 'underscores_scripts' );

/**
 * Implement the Custom Header feature.
 */
require get_template_directory() . '/inc/custom-header.php';

/**
 * Custom template tags for this theme.
 */
require get_template_directory() . '/inc/template-tags.php';

/**
 * Custom functions that act independently of the theme templates.
 */
require get_template_directory() . '/inc/extras.php';

/**
 * Customizer additions.
 */
require get_template_directory() . '/inc/customizer.php';

/**
 * Load Jetpack compatibility file.
 */
require get_template_directory() . '/inc/jetpack.php';

if ( function_exists( 'add_theme_support' ) ) { 
    add_theme_support( 'post-thumbnails' );
    set_post_thumbnail_size( 150, 150, true ); // default Post Thumbnail dimensions (cropped)

    // additional image sizes
    // delete the next line if you do not need additional image sizes
    add_image_size( 'category-thumb', 300, 9999 ); //300 pixels wide (and unlimited height)
}

[index.php]

<?php
/**
 * The main template file.
 *
 * This is the most generic template file in a WordPress theme
 * and one of the two required files for a theme (the other being style.css).
 * It is used to display a page when nothing more specific matches a query.
 * E.g., it puts together the home page when no home.php file exists.
 *
 * @link https://codex.wordpress.org/Template_Hierarchy
 *
 * @package underscores
 */

get_header(); ?>

	<div id="primary" class="content-area">
		<main id="main" class="site-main" role="main">

		<?php
		if ( have_posts() ) :

			if ( is_home() && ! is_front_page() ) : ?>
			
			
			
				<header>
					<h1 class="page-title screen-reader-text"><?php single_post_title(); ?></h1><hr> 
					
					if ( has_post_thumbnail() ) {
the_post_thumbnail();
} 
the_content();

					
					<?php the_excerpt(); ?>
					

				</header>

				

			<?php
			endif;

			/* Start the Loop */
			while ( have_posts() ) : the_post();
		
			
				/*
				 * Include the Post-Format-specific template for the content.
				 * If you want to override this in a child theme, then include a file
				 * called content-___.php (where ___ is the Post Format name) and that will be used instead.
				 */
				get_template_part( 'template-parts/content', get_post_format() );

				
				
			endwhile;

			the_posts_navigation();

			
			
			
		else :

			get_template_part( 'template-parts/content', 'none' );

		endif; ?>
			
		<a class="btn" href="<?php echo the_permalink(); ?>">Read More <span class="glyphicon glyphicon-chevron-right"></span></a>
		</main><!-- #main -->
	</div><!-- #primary -->

<?php
get_sidebar();
get_footer();

wcześniej używałem m.in tej metody:

[funcions / index]

<header>
					<h1 class="page-title screen-reader-text"><?php single_post_title(); ?></h1><hr> 
					
					<!--post-thumbnail by LearnWebCode -->
<div>
<a href="<?php the_permalink(); ?>"><?php the_post_thumbnail('small-thumbnail'); ?></a>
</div><!--/ .post-thumbnail-->
					
					<?php the_excerpt(); ?>
					

				</header>

// Image size
add_theme_support( 'post-thumbnails' );

set_post_thumbnail_size( 50, 50);
// Image size for single posts
add_image_size( 'single-post-thumbnail', 590, 180 );

add_theme_support('post-thumbnails');

function underscores_setup() {

	// Add featured image support
	add_theme_support('post-thumbnails');
	add_image_size('small-thumbnail', 180, 120, true);
	add_image_size('banner-image', 920, 210, array('left', 'top'));
}

add_action('after_setup_theme', 'underscores_setup');

też bez rezultatu, nie znam php, i mogę się tylko domyślać i próbować metodą prób i błędów…

działa – does work !

pana rady i wskazówki okazały się bezcenne, dziękuje z całego serca !!!

aczkolwiek, nie wiem jeszcze m.in. tego, dlaczego u mnie jest najpierw (patrząc od góry do dołu) miniatura obrazka wyróżniającego dla posta, a potem tytuł posta, który logicznie powinien być nad tym zdjęciem (obrazkiem wyróżniającym dla tegoż posta)

w statycznej stronie html/css/js:

kolejność znaczników w kodzie

(…)
<h2 class=””>

<p>
<btn>
(..)

odpowiada temu co widzimy na stronie

w php nie widzę gdzie to zmienić… na jakim ukrytym rejestrze coś „trzyma” tą kolejność

=>

co ciekawe kolejność w głównej pętli bloga [index.php] sugeruję coś innego, i wydaje się być
właśnie prawidłowa, <H2> w kodzie jest nad zdjęciem wyróżniającym, a mimo to już na samej stronie h2 wyświetla się pod zdjęciem…

<?php
/**
 * The main template file.
 *
 * This is the most generic template file in a WordPress theme
 * and one of the two required files for a theme (the other being style.css).
 * It is used to display a page when nothing more specific matches a query.
 * E.g., it puts together the home page when no home.php file exists.
 *
 * @link https://codex.wordpress.org/Template_Hierarchy
 *
 * @package underscores
 */

get_header(); ?>

	<div id="primary" class="content-area">
		<main id="main" class="site-main" role="main">

		<?php
		if ( have_posts() ) :

			if ( is_home() && ! is_front_page() ) : ?>
			
			
			
				<header class="entry-header">
					<h2 class="entry-title"><?php single_post_title(); ?></h2><hr> 
					
					
					
					<?php the_excerpt(); ?>
					

				</header>

				

			<?php
			endif;

			/* Start the Loop */
			while ( have_posts() ) : the_post();
		// check if the post has a Post Thumbnail assigned to it.
if ( has_post_thumbnail() ) {
	the_post_thumbnail();
} 
			
				/*
				 * Include the Post-Format-specific template for the content.
				 * If you want to override this in a child theme, then include a file
				 * called content-___.php (where ___ is the Post Format name) and that will be used instead.
				 */
				get_template_part( 'template-parts/content', get_post_format() );

				
				
			endwhile;

			the_posts_navigation();

			
			
			
		else :

			get_template_part( 'template-parts/content', 'none' );

		endif; ?>
			
		<a class="btn" href="<?php echo the_permalink(); ?>">Read More <span class="glyphicon glyphicon-chevron-right"></span></a>
		</main><!-- #main -->
	</div><!-- #primary -->

<?php
get_sidebar();
get_footer();

Dziękuję za Odpowiedź:

wiem, że mam ogromne zaległości (bo jeszcze zajmuję się innymi rzeczami), w nauce, ale wydaje mi się, że ta kolejność jest nie tyle nie prawidłowa, co nie ma po h2 <tagów> php o thumbnail, hmm:

<?php
/**
 * Template part for displaying posts.
 *
 * @link https://codex.wordpress.org/Template_Hierarchy
 *
 * @package underscores
 */

?>

<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
	<header class="entry-header">
		<?php
		if ( is_single() ) :
			the_title( '<h1 class="entry-title">', '</h1>' );
		else :
			the_title( '<h2 class="entry-title"><a href="' . esc_url( get_permalink() ) . '" rel="bookmark">', '</a></h2>' );
		endif;

                //HERE LACK OF THUMB TAG, if I understand properly...

		if ( 'post' === get_post_type() ) : ?>
		<div class="entry-meta">
			<?php underscores_posted_on(); ?>
		</div><!-- .entry-meta -->
		<?php
		endif; ?>
	</header><!-- .entry-header -->

	<div class="entry-content">
		<?php
			the_content( sprintf(
				/* translators: %s: Name of current post. */
				wp_kses( __( 'Continue reading %s <span class="meta-nav">&rarr;</span>', 'underscores' ), array( 'span' => array( 'class' => array() ) ) ),
				the_title( '<span class="screen-reader-text">"', '"</span>', false )
			) );

			wp_link_pages( array(
				'before' => '<div class="page-links">' . esc_html__( 'Pages:', 'underscores' ),
				'after'  => '</div>',
			) );
		?>
	</div><!-- .entry-content -->

	<footer class="entry-footer">
		<?php underscores_entry_footer(); ?>
	</footer><!-- .entry-footer -->
</article><!-- #post-## -->