📝 Template Tags Part 3: Advanced Usage

Custom fields, conditional tags, and best practices

This lesson is divided into 3 parts:

Part 1: Core Functions Part 2: Meta & Taxonomy Part 3: Advanced Usage

Part 3 Learning Objectives

  • Work with custom fields and post metadata
  • Master conditional tags
  • Learn proper data escaping
  • Create custom template functions

🔧 Custom Fields and Metadata

get_post_meta()

get_post_meta( $post_id, $key, $single )

Retrieves custom field values.

<?php $custom_value = get_post_meta( get_the_ID(), '_custom_field_key', true ); if ( $custom_value ) { echo esc_html( $custom_value ); } ?>

update_post_meta()

update_post_meta( $post_id, $meta_key, $meta_value )

Updates or creates custom field.

<?php $views = get_post_meta(get_the_ID(), '_view_count', true); update_post_meta(get_the_ID(), '_view_count', $views + 1); ?>

❓ Conditional Tags

has_post_thumbnail()

has_post_thumbnail( $post )

Checks if post has featured image.

<?php if ( has_post_thumbnail() ) { the_post_thumbnail(); } else { echo '<img src="default.jpg">'; } ?>

has_excerpt()

has_excerpt( $post )

Checks if post has manual excerpt.

<?php if ( has_excerpt() ) { the_excerpt(); } else { echo wp_trim_words(get_the_content(), 30); } ?>

Data Escaping Best Practices

// Escape HTML
<h1><?php echo esc_html( get_the_title() ); ?></h1>

// Escape URLs
<a href="<?php echo esc_url( get_permalink() ); ?>">Link</a>

// Escape attributes
<input value="<?php echo esc_attr( $value ); ?>">

// Escape JavaScript
<script>
var title = '<?php echo esc_js( get_the_title() ); ?>';
</script>

Creating Custom Template Functions

// Custom post metadata function
function my_theme_post_meta() {
    $output = '<div class="post-meta">';
    $output .= '<span>By ' . get_the_author() . '</span>';
    $output .= '<span>' . get_the_date() . '</span>';
    
    $categories = get_the_category();
    if ( ! empty($categories) ) {
        foreach($categories as $cat) {
            $output .= '<a href="' . get_category_link($cat->term_id) . '">';
            $output .= $cat->name . '</a> ';
        }
    }
    
    $output .= '</div>';
    echo $output;
}

// Reading time calculator
function my_theme_reading_time() {
    $content = get_the_content();
    $word_count = str_word_count(strip_tags($content));
    $reading_time = ceil($word_count / 200);
    echo $reading_time . ' min read';
}

Complete Template Example

<article <?php post_class(); ?>>
    <?php if ( has_post_thumbnail() ) : ?>
        <div class="featured-image">
            <?php the_post_thumbnail('large'); ?>
        </div>
    <?php endif; ?>
    
    <header>
        <?php the_title('<h1>', '</h1>'); ?>
        <div class="meta">
            <?php the_author_posts_link(); ?>
            <?php echo get_the_date(); ?>
            <?php the_category(', '); ?>
        </div>
    </header>
    
    <div class="entry-content">
        <?php the_content(); ?>
    </div>
    
    <footer>
        <?php the_tags('Tags: ', ', ', ''); ?>
    </footer>
</article>

Best Practices Summary

  • Always escape output with appropriate functions
  • Use conditional tags to check before displaying
  • Cache expensive operations in variables
  • Use get_ functions when manipulating data
  • Provide fallbacks for missing data
  • Internationalize all text strings

Resources