WP_Query in WordPress - InimistTech Blogs

WP_Query in WordPress queries and displays posts based on specific parameters. It allows developers to customize how content is retrieved and displayed, offering a more flexible alternative to the default loop.

What is WP_Query?

WP_Query is primarily used for:
1) Filtering posts based on custom criteria (categories, tags, custom post types, etc.).
2) Creating custom loops to display content in specific layouts.

Basic Example of WP_Query

Here’s a simple example where we retrieve the latest five blog posts:

<?php

$args = array(
    'post_type' => 'post', // Fetch posts (you can also use 'page' or custom post types)
    'posts_per_page' => 5, // Limit to 5 posts
    'orderby' => 'date',   // Order by post date
    'order' => 'DESC'      // Show most recent first
);
$query = new WP_Query($args);

if($query->have_posts()) :
    while($query->have_posts()) : $query->the_post();
        the_title('<h2>', '</h2>');  // Display post title
        the_excerpt();               // Display excerpt
    endwhile;
    wp_reset_postdata();  // Reset query data
else:
    echo 'No posts found';
endif;

?>

Example Use Cases for WP_Query

1. Query Posts by Category

You can retrieve posts from a specific category using category_name. The following example pulls posts from the “news” category:

<?php
$args = array(
    'category_name' => 'news', // Fetch posts from 'news' category
    'posts_per_page' => 3,     // Limit to 3 posts
);
$query = new WP_Query($args);

?>

2. Query Custom Post Types

WP_Query allows you to work with custom post types. In this example, we retrieve four portfolio items:

<?php
$args = array(
    'post_type' => 'portfolio',  // Custom post type: 'portfolio'
    'posts_per_page' => 4,       // Limit to 4 items
);
$query = new WP_Query($args);

?>

3. Meta Query (Custom Fields)

You can filter posts based on custom fields (meta data). Here’s an example that queries products with a custom field price greater than 100:

<?php
$args = array(
    'post_type' => 'product',  // Custom post type: 'product'
    'meta_query' => array(     // Meta query to filter by custom field 'price'
        array(
            'key' => 'price',
            'value' => 100,
            'compare' => '>',
            'type' => 'NUMERIC'
        )
    )
);
$query = new WP_Query($args);
?>

Pagination with WP_Query

WP_Query supports pagination using the paged parameter. You can use it to paginate your content like this:

<?php
$paged = (get_query_var('paged')) ? get_query_var('paged') : 1;

$args = array(
    'post_type' => 'post',
    'posts_per_page' => 5,
    'paged' => $paged
);

$query = new WP_Query($args);

if($query->have_posts()) :
    while($query->have_posts()) : $query->the_post();
        the_title('<h2>', '</h2>');
    endwhile;

    previous_posts_link('Previous');  // Display link to previous page
    next_posts_link('Next', $query->max_num_pages);  // Display link to next page
    wp_reset_postdata();
else:
    echo 'No posts found';
endif;

?>

Conclusion:

WP_Query is a versatile tool in WordPress that customizes how posts are retrieved and displayed. Whether you want to filter posts by category, custom fields, or post
types, WP_Query provides endless possibilities for building dynamic content layouts.
This class is indispensable for WordPress developers looking to extend the functionality of WordPress themes and plugins.