WP_Query class in Wordpress - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What does this WP_Query output?

Consider this WordPress code snippet using WP_Query. What posts will it retrieve and display?

Wordpress

<?php
$query = new WP_Query(['category_name' => 'news', 'posts_per_page' => 3]);
if ($query->have_posts()) {
  while ($query->have_posts()) {
    $query->the_post();
    echo get_the_title() . '\n';
  }
}
wp_reset_postdata();
?>

A It outputs the titles of the latest 3 posts in the 'news' category.

B It outputs all posts except those in the 'news' category.

C It outputs the titles of the first 3 posts ever published, ignoring category.

D It outputs the titles of 3 random posts from any category.

💡 Hint

Look at the 'category_name' and 'posts_per_page' parameters in WP_Query.

The WP_Query is set to fetch posts from the 'news' category only, limited to 3 posts. The loop outputs their titles.

📝 Syntax

intermediate

Which WP_Query argument array is valid?

Which of the following WP_Query argument arrays will NOT cause a syntax error?

A ['post_type' => 'post', 'posts_per_page' => 'five']

B ['post_type' => 'post' 'posts_per_page' => 5]

C ['post_type' => 'post', posts_per_page => 5]

D ['post_type' => 'page', 'posts_per_page' => 5]

💡 Hint

Check for missing commas and correct string keys.

Option D is a valid PHP associative array with correct syntax. Option D misses a comma. Option D misses quotes around the key. Option D uses a string 'five' instead of an integer for posts_per_page, which is allowed but not recommended; however, it won't cause syntax error but may cause unexpected behavior.

❓ state_output

advanced

What is the value of $count after this WP_Query?

Given this code, what is the value of $count after execution?

Wordpress

<?php
$query = new WP_Query(['tag' => 'featured']);
$count = 0;
if ($query->have_posts()) {
  while ($query->have_posts()) {
    $query->the_post();
    $count++;
  }
}
wp_reset_postdata();
?>

A The number of posts tagged with 'featured'.

B Always 0 because $count is reset inside the loop.

C The total number of posts in the database.

D Always 1 because the loop runs once.

💡 Hint

Count increments inside the loop for each post found.

The variable $count increases by 1 for each post found with the 'featured' tag. So it equals the number of such posts.

🔧 Debug

advanced

Why does this WP_Query return no posts?

This code returns no posts even though posts exist. What is the problem?

Wordpress

<?php
$query = new WP_Query(['category' => 'news']);
if ($query->have_posts()) {
  while ($query->have_posts()) {
    $query->the_post();
    echo get_the_title() . '\n';
  }
}
wp_reset_postdata();
?>

A The posts_per_page parameter is missing, so no posts are returned by default.

B 'category' is not a valid WP_Query parameter; it should be 'category_name' or 'cat'.

C The loop is missing a call to rewind_posts(), so it skips all posts.

D The wp_reset_postdata() call is inside the loop, causing it to reset early.

💡 Hint

Check the parameter names for filtering by category.

The parameter 'category' is not recognized by WP_Query. To filter by category slug, use 'category_name'. To filter by category ID, use 'cat'.

🧠 Conceptual

expert

Which WP_Query argument combination fetches posts from multiple categories?

You want to fetch posts that belong to either category ID 4 or 7. Which WP_Query argument array achieves this?

A ['cat' => '4,7']

B ['category__and' => [4, 7]]

C ['category__in' => [4, 7]]

D ['category_name' => '4,7']

💡 Hint

Check the difference between category__in and category__and parameters.

To get posts in either category 4 or 7, use 'category__in' with an array of IDs. 'cat' expects a comma-separated string but treats it as posts in both categories (AND). 'category__and' fetches posts in both categories simultaneously. 'category_name' expects slugs, not IDs.