How to write optimized WP_Query in WordPress[2 example]?

WordPress comes with lots of built-in functionalities. And one of the most used functionality is the WP_Query class. We play around WP_Query every day. Today let’s see how to write optimized WP_Query in WordPress?

What is WP_Query?

WP_Query is WordPress’s default PHP class to create queries for posts, pages, custom post types, authors, and many more. With the help of WP_Query, we do not need to write a separate database query for our needs. It allows us to build a complex search from the database and give the response.

WP_Query is used with the loop. WP_Query has many arguments to build a query that sometimes makes it heavy to search. That’s why today we will see how to use WP_Query class efficiently and write an optimized way.

WP_Query default structure

We can use WP_Query by creating an instance of the class with the required arguments $args. You must pass the arguments in $args to fetch the data.

<?php
// WP_Query
$query = new WP_Query( $args );

if ( $query->have_posts() ) :

	while ( $query->have_posts() ) : $query->the_post();
	?>
		<h2><?php the_title(); ?></h2>
	<?php
	endwhile;

	wp_reset_postdata();

else:
	// No any post found!
endif;
?>

Get the recent 5 posts

Now let’s see about the arguments in some detail, and how can you use them. We will get the recent 5 posts with WP_Query.

<?php
// WP_Query

$args = [
    'post_type'      => 'post',
    'post_status'    => 'publish',
    'posts_per_page' => '5',
    'orderby'        => 'date',
    'order'          => 'DESC',
];

$query = new WP_Query( $args );

if ( $query->have_posts() ) :

	while ( $query->have_posts() ) : $query->the_post();
	?>
		<div class="posts-wrap">
			<h2><?php the_title(); ?></h2>
		</div>
	<?php
	endwhile;

	wp_reset_postdata();

else:
	// No any post found!
endif;
?>

In the above example, we have used multiple arguments to get 5 recent posts. Let’s discuss them one by one.

• post_type: Post type name like the post, page, attachment, revision, etc;
• post_status: Post status like publish, draft, pending, etc.
• posts_per_page: Number of posts needed.
• orderby: Order post by the date, title, ID, etc.
• order: ASC , DESC. Ascending or Descending order.

Most used queries in WP_Query

We can also make the query with the below queries.

• Taxonomy query(tax_query): With the help of tax_query we can get the post by particular category/categories. We can include and exclude the category in the array.
  
  Refer to this: https://developer.wordpress.org/reference/classes/wp_query/#taxonomy-parameters
  
• Meta fields(meta_query): With the help of meta_query we can get the post based on meta values. Like if we want to get the post of the particular meta field value.
  
• Date query(date_query): We the help of this date_query we can get the post by the particular date and time.
  
  Refer to this: https://developer.wordpress.org/reference/classes/wp_query/#taxonomy-parameters

Refer to their official documents for more details.

Write optimized WP_Query

Here I’m sharing the most awaited things about optimized WP_Query. Here is something you need to know when you write the WP_Query.

• Always avoid 'posts_per_page' => '-1' in the query. Keep the appropriate number. What if the post count is 50000? That will cause the site performance.
• Use 'no_found_rows' => true when you are not using pagination. That will not run the extra database query to get the post count and the number of pages for pagination.
• Use 'fields' => 'ids' when you need only the post ID.
• Use 'update_post_meta_cache' => false, when you don’t require the meta.
• Use 'update_post_term_cache' => false, when the taxonomy term is not used.

So let’s see again a small example:

<?php
// WP_Query

$args = [
	'post_type'              => 'post',
    'post_status'            => 'publish',
    'posts_per_page'         => '5',
    'orderby'                => 'date',
    'order'                  => 'DESC',
    'no_found_rows'          => true,
    'update_post_meta_cache' => false,
    'update_post_term_cache' => false,
    'fields'                 => 'ids',
];

$query = new WP_Query( $args );

if ( $query->have_posts() ) :

	while ( $query->have_posts() ) : $query->the_post();
	?>
		<div class="posts-wrap">
			<h2><?php the_title(); ?></h2>
		</div>
	<?php
	endwhile;

	wp_reset_postdata();

else:
	// No any post found!
endif;
?>

So this way you can write an optimized WP_Query. That will give you a better performance.

Avoid post__not_in

We use post__not_in for not including that post in a query. We probably use this functionality on the article page. So when we show a recent post or some particular posts then we can exclude the current post from it.

If we use post__not_in in our query then every time that query will leverage a unique cache for all posts and that will affect site performance. So instead of that we can check that thing in a loop and can filter the not needed posts. See the below example.

$args = array(
    'post_type'      => 'page',
    'post_status'    => 'publish',
    'posts_per_page' => 5 + count( $exclude_posts ), // $exclude_posts is an array of post IDs
    'no_found_rows'  => true,
);
$query = new WP_Query( $args );

while ( $query->have_posts() ) {
    $query->the_post();
    $current_post = get_the_ID();
    if ( in_array( $current_post, $exclude_posts ) ) {
        continue;
    }
    the_title( '<h2><a href="' . get_permalink() . '">', '</a></h2>');
}

wp_reset_postdata();

Hope you like the article!

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