More Information

Use this function to restore the context of the template tags from a secondary query loop back to the main query loop.

Differences between the main query loop and secondary query loops are:

• the main query loop is based on the URL request and is initialised before theme templates are processed
• secondary query loops are queries (using new WP_Query) in theme template or plugin files

A secondary query loop using $sec_query = new WP_Query() and $sec_query->the_post() affects the global $post variable. The global $post variable is used by template tags by default. wp_reset_postdata() restores the global $post variable to the current post in the main query (contained in the global $wp_query variable as opposed to the $sec_query variable), so that the template tags refer to the main query loop by default again.

Example

<?php 
$args = array( 'posts_per_page' => 3 );

// the query
$sec_query = new WP_Query( $args );
?>

<?php if ( $sec_query->have_posts() ) : ?>

<!-- start of the loop. the_post() sets the global $post variable -->
<?php while ( $sec_query->have_posts() ) : $sec_query->the_post(); ?>

    <!-- template tags will return values from the post in the $sec_query object
    <?php the_title(); ?>
    <?php the_excerpt(); ?>

<?php endwhile; ?><!-- end of the loop -->

<!-- reset global post variable. After this point, we are back to the Main Query object -->
<?php wp_reset_postdata(); ?>

<?php else: ?>

<?php _e( 'Sorry, no posts matched your criteria.' ); ?>

<?php endif; ?>