掌握 WP_Query：10个有用的例子

<?php

if ( have_posts() ) {

    while ( have_posts() ) {

        the_post();

        // Post data goes here.

    }

}

?>

<?php

$args = array(
    'category_name' => 'news',
    'posts_per_page' => 3
);

$my_query = new WP_Query( $args );

if ( $my_query->have_posts() ) {

    while ( $my_query->have_posts() ) {

        $my_query->the_post();

        // Post data goes here.

    }

}

// Reset the `$post` data to the current post in main query.
wp_reset_postdata();

?>

<?php

// Get the year we're in.
$current_year = date( 'Y' );

// Setup arguments.
$args = array(
    // Get the author with the nicename "john".
    'author' => 'john',
    // Get his posts from this year.
    'year'   => $current_year
);

// Instantiate new query instance.
$my_query = new WP_Query( $args );

?>

<?php

// Get the current post id.
$current_post_id = get_the_ID();

// Get the current post's category (first one if there's more than one).
$current_post_cats = get_the_category();
$current_post_first_cat_id = $current_post_cats[ 0 ]->term_id;

// Setup arguments.
$args = array(
    // Get category's posts.
    'cat' => $current_post_first_cat_id,
    // Exclude current post.
    'post__not_in' => array( $current_post_id )
);

// Instantiate new query instance.
$my_query = new WP_Query( $args );

?>

<?php

// Setup arguments.
$args = array(
    // Order by comment count.
    'orderby' => 'comment_count'
);

// Instantiate new query instance.
$my_query = new WP_Query( $args );

?>

<?php

// Setup arguments.
$args = array(
    // Get the "slider" post type.
    'post_type' => 'slider',
    // Get a specific slider category.
    'category_name' => 'home-slides',
    // Get all slides and don't paginate.
    'nopaging' => true
);

// Instantiate new query instance.
$my_query = new WP_Query( $args );

?>

<?php

/* 
 * Create new post type called "Quotes"
 * (refer to the `register_post_type` function to
 * learn more about creating custom post types).
 */
function quote_post_type() {

    $args = array(
        'label' => 'Quotes',
        'public' => true
    );

    register_post_type( 'quotes', $args );
}

add_action( 'init', 'quote_post_type' );

// Setup arguments.
$args = array(
    // Get the "quotes" psot type.
    'post_type' => 'quotes',
    // Randomize the order.
    'orderby' => 'rand',
    // Get only one item.
    'posts_per_page' => 1,
);

// Instantiate new query instance.
$my_query = new WP_Query( $args );

?>

<?php

// Source: http://scribu.net/wordpress/advanced-metadata-queries.html

// Setup arguments.
$args = array(
    // Get the "product" post type.
    'post_type' => 'product',
    // Setup the "meta query".
    'meta_query' => array(
        array(
            // Get the "price" custom field.
            'key' => 'price',
            // Set the price values.
            'value' => array( 100, 200 ),
            // Set the compare operator.
            'compare' => 'BETWEEN',
            // Only look at numeric fields.
            'type' => 'numeric',
        )
    )
);

// Instantiate new query instance.
$my_query = new WP_Query( $args );

?>

<?php

/*
 * Usage:
 *
 * [embed_post slug="my-post"]
 * [embed_post slug="my-post" full="false"]
 * [embed_post type="movie" slug="inception"]
 */

function tutsplus_embedded_post_shortcode( $attributes ) {

    // Extract shortcode attributes.
    extract(
        shortcode_atts(
            array(
                'type' => 'post',
                'slug' => '',
                'full' => true
            ),
            $attributes
        )
    );

    // Setup arguments.
    $args = array(
        // Get post type ("post" by default).
        'post_type' => $type,
        // Get post by slug.
        'name' => $slug
    );

    // Instantiate new query instance.
    $my_query = new WP_Query( $args );

    // Check that we have query results.
    if ( $my_query->have_posts() ) {

        // Begin generating markup.
        $output = '<section class="embedded-post">';

        // Start looping over the query results.
        while ( $my_query->have_posts() ) {

            $my_query->the_post();

            // Add title to output.
            $output .= '<h2 class="embedded-post-title">';
                $output .= get_the_title();
            $output .= '</h2>';

            // Get full post if `$full` is true, otherwise, show the get excerpt
            if ( 'true' === $full ) {

                // Add full content to output.
                $output .= '<div class="embedded-post-content">';
                    $output .= get_the_content();
                $output .= '</div>';

            } else {

                // Add excerpt to output.
                $output .= '<div class="embedded-post-excerpt">';
                    $output .= get_the_excerpt();
                    $output .= '… <a rel="nofollow noopener noreferrer" href="' . get_permalink() . '">' . __( 'See full post', 'tutsplus' ) . ' »</a>';
                $output .= '</div>';

            }

        }

        // End generating markup.
        $output .= '</section>';

    } else {

        // Output message to let user know that no posts were found.
        $output = '<section class="embedded-post-error">';
            $output .= '<p>' . __( 'No posts found.', 'tutsplus' ) . '</p>';
        $output .= '</section>';

    }

    wp_reset_postdata();

    return $output;

}

add_shortcode( 'embed_post', 'tutsplus_embedded_post_shortcode' );

?>

<?php

/*
 * Usage with Excerpts:
 *
 * <?php echo tutsplus_show_drafts(); ?>
 *
 * Usage without Excerpts:
 *
 * <?php echo tutsplus_show_drafts( false ); ?>
 */

function tutsplus_show_drafts( $show_excerpts = true ) {

    // Setup arguments.
    $args = array(
        'post_status' => 'future',
        'nopaging' => true
    );

    // Instantiate new query instance.
    $my_query = new WP_Query( $args );

    // Check that we have query results.
    if ( $my_query->have_posts() ) {

        // Begin generating markup.
        $output = '<section class="pending-posts">';

        // Start looping over the query results.
        while ( $my_query->have_posts() ) {

            $my_query->the_post();

            // Output draft post title and excerpt (if enabled).
            $output .= '<div class="pending">';
                $output .= '<h3 class="pending-title">' . get_the_title() . '</h3>';
                    $output .= get_the_title();
                $output .= '</h3>';

                if ( $show_excerpts ) {

                    $output .= '<div class="pending-excerpt">';
                        $output .= get_the_excerpt();
                    $output .= '</div>';

                }

            $output .= '</div>';

        }

        // End generating markup.
        $output .= '</section>';

    } else {

        // Let user know that nothing was found.
        $output = '<section class="drafts-error">';
            $output .= '<p>' . __( 'Nothing found', 'tutsplus' ) . '</p>';
        $output .= '</section>';

    }

    wp_reset_postdata();

    return $output;

}

?>

<?php

// Setup arguments.
$args = array(
    // Day (1 - 31).
    'day' => date( 'j' ),
    // Month (1 - 12).
    'monthnum' => date( 'n' ),
    // Year (minus 1).
    'year' => date( 'Y' ) - 1,
    // Show only one post.
    'posts_per_page' => 1
);

// Instantiate new query instance.
$my_query = new WP_Query( $args );

?>

<?php

$current_page_id = get_the_ID();

// Setup arguments.
$args = array(
    // Get children of current page.
    'parent' => $current_page_id,
    // Disable pagination.
    'nopaging' => true
);

// Instantiate new query instance.
$my_query = new WP_Query( $args );

?>