The default blog page shows all the posts on your site using the standard design of the theme. Sometimes, we want to display a set of selected posts inside a page as a grid with a customized design to promote them. We can use shortcode inside a page or create a page template to provide this functionality.

In this recipe, we are going to create a page template that will display a list of posts in a grid-based design.

Open the code editor and make sure you have access to the theme files in your local or external WordPress installation. Also, you need to add featured images to a few of the existing posts in order to see the complete design of Post Grid in action.

Follow these steps to create a custom page template that will display a list of posts as a grid:

1. Open the wp-content/themes/twentytwentychild folder using a file manager.
2. Create a new template called post-grid.php.
3. Add the following code to the post-grid.php file, define it as a template, and save the changes:

<?php /* Template Name: Post Grid */ ?>

4. Add the following code after the template name definition to load the header and retrieve the posts:

<?php
  get_header();
  $post_list = new WP_Query(array('post_type'=>'post',  
  'post_status'=>'publish', 'posts_per_page'=>-1)); 
?>

5. Now, we can add the following template code after the code in step 4. This code will be used to display the posts list:

<?php if ( $post_list->have_posts() ) : ?>
  <div id="list-post-panel">
    <ul>
      <?php while ( $post_list->have_posts() ) : 
       $post_list->the_post();
        $image = get_the_post_thumbnail_url( get_the_ID()); ?>
        <li>
          <div class="post-list-featured-image"><img src="<?php 
           echo $image; ?>" /></div>
          <div class="post-list-title"><a href="<?php 
           the_permalink(); ?>"><?php the_title(); ?></a></div>
       </li>
     <?php endwhile; ?>
    </ul>
    <?php wp_reset_postdata(); ?>
<?php else : ?>
  <p><?php _e( 'There no posts to display.' ); ?></p>
<?php endif; ?>
</div>
<?php get_footer(); ?>

6. Add the following styles to the style.css file of the Twenty Twenty child theme to display the post list as a grid:

#list-post-panel ul { width : 100%; list-style:none; }
#list-post-panel li{ 
 width: 31%;
 margin: 1%;
 padding: 1%;
 float: left;
 background: #eee;
 list-style: none;
 text-align: center;
 border: 1px solid #cfcfcf; 
}

.post-list-featured-image img{ 
 width: 100%;
 height: 200px; 
}

7. Log in to the site as an administrator.
8. Click the Posts menu,
9. Click the Add New button to create a new post.

10. Set the title for the post to Grid 1 and upload a featured image using the Set featured image button in the Featured image section:

7. Click the Publish button to create the post.
8. Follow steps 8 to 11 and create two more posts called Grid 2 and Grid 3.
9. Click the Pages menu.
10. Click the Add New button to create a new page.
11. Add a title for the page and select Post Grid as the template under the Page Attributes | Template settings.
12. Click the Publish button to create the page.

Now, you can view this page on the frontend. Here, you will see a grid-based post list, as shown in the following screenshot:

Here, we have a grid-based post list design with a three-column layout. This is a basic version of a modern grid template in order to keep up with the scope of this book.

You can improve this design with animation effects and AJAX-based lazy loading.

Let's identify how the template code works by using the following steps:

1. First, we call the get_header function to include the default header for the template.
2. Then, we add the Template Name: Post Grid comment to the post-grid.php file. Once this is added, it will be available for selection in the Page Attributes | Template setting section of the page edit screen, even without any template code.
3. Next, we add the header and the query for retrieving posts. We did this in Step 5. In this scenario, we are loading all the published normal posts in the site.
4. Then, we use the have_posts function on $post_list to check if any posts are being returned from the query. Once results are found, we traverse through the resultset using a while loop and add the post-related information inside an unordered list.

5. We use the built -in get_the_post_thumbnail_url, the_permalink, and the_title functions to retrieve the featured post image URL, the link of the post, and the title.
6. Next, we use the wp_reset_postdata function to restore the loop back to the main query of the post or page. Adding this function is essential to preventing conflicts in data loading in the main query after our secondary query has been executed.

7. Next, we added the get_footer function to add the default footer and complete the page template.
8. Finally, we added the CSS of the <ul> and <li> tags to make a grid type design with three columns. We used 31% as the width and float:left on the <li> tag to divide the list into three columns. Then, we set width:100% and fixed the height to 200px to make it look similar on all the posts, regardless of the uploaded image size.

Now, you understand how the template code works.

In this recipe, we loaded the list of all the normal posts in the site. This is a primary implementation of a post list template. In the real world, these templates are used for displaying custom post types or filtered sets of posts instead of all posts. Let's take a look at the scenarios where we can change the query to make the template much more flexible:

• Displaying a custom post in a list template: We can modify the query to display a list of entries from a custom post type such as WooCommerce products by changingpost_type:

$post_list = new WP_Query(array('post_type'=>'product', 'post_status'=>'publish', 'posts_per_page'=>-1));

• Displaying posts from a specific category: We can modify the query to display posts only from the category specified in the category_name parameter:

$post_list = new WP_Query(array('post_type'=>'post', 'post_status'=>'publish', 'category_name' => 'books', 'posts_per_page'=>-1));

• Displaying posts with more than x number of comments: We can modify the query to display a list of posts that have more than 10 comments:

$post_list = new WP_Query(array('post_type'=>'post', 'post_status'=>'publish', 'comment_count' => array( 'value' => 10,   'compare' => '>=',    ), 'posts_per_page'=>-1));

The WP_Query class provides a large number of such query parameters, so the possibilities are endless. You can view all the available query parameters at https://developer.wordpress.org/reference/classes/wp_query/.