Content Management Concepts

Basic Query Example

// Create a new query for recent posts
$recent_posts_query = new WP_Query(array(
    'post_type' => 'post',
    'posts_per_page' => 5,
    'orderby' => 'date',
    'order' => 'DESC'
));

// The Loop
if ($recent_posts_query->have_posts()) :
    while ($recent_posts_query->have_posts()) : $recent_posts_query->the_post();
        ?>
        <article>
            <h2><a href=""></a></h2>
            <div class="meta">Posted on  by </div>
            <div class="excerpt"></div>
        </article>
        No posts found</p>';
endif;

Advanced Query Examples

// Query for a specific post type with taxonomy terms
$project_query = new WP_Query(array(
    'post_type' => 'project',
    'posts_per_page' => 10,
    'tax_query' => array(
        array(
            'taxonomy' => 'project_type',
            'field' => 'slug',
            'terms' => 'web-design'
        ),
        array(
            'taxonomy' => 'skill',
            'field' => 'slug',
            'terms' => array('javascript', 'php'),
            'operator' => 'AND' // Posts must have all these terms
        )
    )
));

// Query with meta value filtering
$featured_products = new WP_Query(array(
    'post_type' => 'product',
    'meta_query' => array(
        'relation' => 'AND',
        array(
            'key' => '_featured',
            'value' => '1',
            'compare' => '='
        ),
        array(
            'key' => '_price',
            'value' => 100,
            'type' => 'NUMERIC',
            'compare' => '<'
        )
    ),
    'orderby' => 'meta_value_num',
    'meta_key' => '_price',
    'order' => 'ASC'
));

// Date-based queries
$events_query = new WP_Query(array(
    'post_type' => 'event',
    'posts_per_page' => -1, // All posts
    'meta_key' => '_event_date',
    'orderby' => 'meta_value',
    'order' => 'ASC',
    'meta_query' => array(
        array(
            'key' => '_event_date',
            'value' => date('Y-m-d'), // Today's date
            'compare' => '>=', // Events from today forward
            'type' => 'DATE'
        )
    )
));

The Basic Loop Structure

// Start the Loop
if (have_posts()) :
    while (have_posts()) : the_post();
        // Post content goes here
        ?>
        <article id="post-" >
            <h2><a href=""></a></h2>
            <div class="entry-content">
                
            </div>
        </article>
        No content found</p>';
endif;

Common Template Tags in The Loop

// Post identification
the_ID();        // Outputs the post ID
post_class();    // Outputs CSS classes for the post

// Post content
the_title();             // Outputs the post title
the_content();           // Outputs the full post content
the_excerpt();           // Outputs the post excerpt
the_permalink();         // Outputs the URL for the post

// Post metadata
the_time('F j, Y');      // Outputs the post date
the_author();            // Outputs the post author's display name
the_author_link();       // Outputs the author name with link to archive
the_category(', ');      // Outputs the post categories
the_tags();              // Outputs the post tags
comments_number();       // Outputs the comment count

// Featured image
if (has_post_thumbnail()) {
    the_post_thumbnail('medium');  // Outputs the featured image
}

// Custom fields
echo get_post_meta(get_the_ID(), 'custom_field', true);

// Edit link (for logged-in users with permission)
edit_post_link('Edit this post', '<div class="edit-link">', '</div>');

function modify_query_examples($query) {
    // Only modify the main query on the frontend
    if (!is_admin() && $query->is_main_query()) {
        // For category archives, show 20 posts instead of the default
        if ($query->is_category()) {
            $query->set('posts_per_page', 20);
        }
        
        // For the blog page, exclude a category
        if ($query->is_home()) {
            $query->set('cat', '-5'); // Exclude category with ID 5
        }
        
        // For search results, include custom post types
        if ($query->is_search()) {
            $query->set('post_type', array('post', 'page', 'product', 'event'));
        }
        
        // For custom post type archives, customize ordering
        if ($query->is_post_type_archive('event')) {
            $query->set('meta_key', '_event_date');
            $query->set('orderby', 'meta_value');
            $query->set('order', 'ASC');
            
            // Only show future events
            $today = date('Y-m-d');
            $query->set('meta_query', array(
                array(
                    'key' => '_event_date',
                    'value' => $today,
                    'compare' => '>=',
                    'type' => 'DATE'
                )
            ));
        }
    }
}
add_action('pre_get_posts', 'modify_query_examples');

Displaying Featured Images

// Check if post has a featured image
if (has_post_thumbnail()) {
    // Display the featured image
    the_post_thumbnail('large'); // Use specific image size
    
    // Or with additional attributes
    the_post_thumbnail(
        'medium', 
        array(
            'class' => 'featured-image',
            'alt' => get_the_title()
        )
    );
}

// Get the image URL instead of the HTML
$thumbnail_url = get_the_post_thumbnail_url(get_the_ID(), 'full');

Working with Image Sizes

// Register custom image sizes (typically in functions.php)
add_action('after_setup_theme', 'custom_image_sizes');
function custom_image_sizes() {
    // Add theme support for featured images
    add_theme_support('post-thumbnails');
    
    // Add custom image sizes
    add_image_size('product-thumbnail', 300, 300, true); // Width, height, crop
    add_image_size('hero-banner', 1920, 600, true);
    add_image_size('square-medium', 400, 400, true);
}

// Get an image by ID with a specific size
$image = wp_get_attachment_image(
    $attachment_id, 
    'product-thumbnail', 
    false, 
    array('class' => 'product-image')
);

// Get just the image URL
$image_url = wp_get_attachment_image_url($attachment_id, 'full');

Getting Image Metadata

// Get attachment metadata
$attachment_metadata = wp_get_attachment_metadata($attachment_id);

// Get attachment caption, description, etc.
$attachment = get_post($attachment_id);
$caption = $attachment->post_excerpt;
$description = $attachment->post_content;
$alt_text = get_post_meta($attachment_id, '_wp_attachment_image_alt', true);

Creating Image Galleries

// Using the gallery shortcode
echo do_shortcode('[gallery ids="1,2,3,4,5" columns="3" size="medium"]');

// Custom gallery implementation
$gallery_ids = get_post_meta(get_the_ID(), 'gallery_images', true);
if ($gallery_ids) {
    echo '<div class="custom-gallery">';
    foreach ($gallery_ids as $image_id) {
        $image_url = wp_get_attachment_image_url($image_id, 'large');
        $image_alt = get_post_meta($image_id, '_wp_attachment_image_alt', true);
        echo '<div class="gallery-item">';
        echo '<img src="' . esc_url($image_url) . '" alt="' . esc_attr($image_alt) . '">';
        echo '</div>';
    }
    echo '</div>';
}

// Example front-end form handling for file uploads
function handle_file_upload() {
    // Check for nonce for security
    if (!isset($_POST['my_upload_nonce']) || !wp_verify_nonce($_POST['my_upload_nonce'], 'my_upload_action')) {
        wp_die('Security check failed');
    }
    
    // Check if file is present
    if (!isset($_FILES['my_file_upload'])) {
        return new WP_Error('no_file', 'No file uploaded');
    }
    
    // Check file type
    $file = $_FILES['my_file_upload'];
    $allowed_types = array('image/jpeg', 'image/png', 'image/gif');
    
    if (!in_array($file['type'], $allowed_types)) {
        return new WP_Error('invalid_type', 'Invalid file type');
    }
    
    // Include necessary file handling functions
    require_once(ABSPATH . 'wp-admin/includes/file.php');
    require_once(ABSPATH . 'wp-admin/includes/image.php');
    require_once(ABSPATH . 'wp-admin/includes/media.php');
    
    // Handle file upload
    $attachment_id = media_handle_upload('my_file_upload', 0);
    
    if (is_wp_error($attachment_id)) {
        return $attachment_id; // Return error
    }
    
    return $attachment_id; // Return new attachment ID
}

// Usage in form submission handling
function process_my_form() {
    if (isset($_POST['submit_upload'])) {
        $attachment_id = handle_file_upload();
        
        if (!is_wp_error($attachment_id)) {
            // Successfully uploaded
            // Maybe associate with a post
            set_post_thumbnail($post_id, $attachment_id);
            
            // Or store the ID in post meta
            update_post_meta($post_id, 'custom_image', $attachment_id);
        }
    }
}