Custom post type queries in Wordpress - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this WP_Query for a custom post type?

Consider this WordPress code querying a custom post type 'book'. What does echo $query->found_posts; output?

Wordpress

<?php
$args = [
  'post_type' => 'book',
  'posts_per_page' => 5,
  'post_status' => 'publish'
];
$query = new WP_Query($args);
echo $query->found_posts;
?>

A The number of posts returned on this page, which can be less than 5

B The total number of published 'book' posts in the database

C Always 5, because posts_per_page is 5

D The total number of posts of any post type in the database

💡 Hint

Think about what found_posts means in WP_Query.

found_posts gives the total count of posts matching the query, ignoring pagination limits like posts_per_page. So it shows how many 'book' posts are published in total.

❓ component_behavior

intermediate

How does 'meta_query' affect a custom post type query?

Given this WP_Query for 'movie' post type with a meta_query filtering by 'rating' > 7, what posts are returned?

Wordpress

<?php
$args = [
  'post_type' => 'movie',
  'meta_query' => [
    [
      'key' => 'rating',
      'value' => 7,
      'compare' => '>',
      'type' => 'NUMERIC'
    ]
  ]
];
$query = new WP_Query($args);
?>

A Only posts with 'rating' meta key, ignoring post type

B All 'movie' posts regardless of 'rating' meta value

C Posts of any type with 'rating' meta value greater than 7

D Only 'movie' posts with a 'rating' meta value greater than 7

💡 Hint

Remember that 'post_type' limits the query to that type, and 'meta_query' filters by meta fields.

The query returns posts of type 'movie' that have a meta field 'rating' with a numeric value greater than 7. Other posts or those with lower ratings are excluded.

📝 Syntax

advanced

Which WP_Query argument array correctly queries 'event' posts ordered by custom field 'event_date'?

Choose the correct argument array to query 'event' custom post type ordered by 'event_date' meta key ascending.

A { 'post_type' => 'event', 'orderby' => 'event_date', 'order' => 'ASC' }

B { 'post_type' => 'event', 'meta_key' => 'event_date', 'orderby' => 'meta_value', 'order' => 'DESC' }

C { 'post_type' => 'event', 'meta_key' => 'event_date', 'orderby' => 'meta_value_num', 'order' => 'ASC' }

D { 'post_type' => 'event', 'meta_key' => 'event_date', 'orderby' => 'date', 'order' => 'ASC' }

💡 Hint

Ordering by a numeric custom field requires specific keys.

To order by a numeric meta field, use 'meta_key' with 'orderby' set to 'meta_value_num' and 'order' ascending or descending as needed.

🔧 Debug

advanced

Why does this WP_Query for 'product' post type return no posts?

Examine this code snippet. Why does it return zero posts?

Wordpress

<?php
$args = [
  'post_type' => 'product',
  'tax_query' => [
    [
      'taxonomy' => 'product_cat',
      'field' => 'slug',
      'terms' => 'electronics'
    ]
  ],
  'posts_per_page' => 10
];
$query = new WP_Query($args);
?>

A The 'terms' value 'electronics' does not exist in 'product_cat' taxonomy

B The taxonomy 'product_cat' is not registered for 'product' post type

C Missing 'relation' key in 'tax_query' array causes failure

D The 'field' should be 'id' not 'slug' for taxonomy queries

💡 Hint

Check if the term slug exists in the taxonomy.

If the term slug 'electronics' does not exist in the 'product_cat' taxonomy, the query returns no posts. The other parts are valid.

🧠 Conceptual

expert

What is the effect of 'suppress_filters' => false in a custom post type query?

In a WP_Query for a custom post type, what does setting 'suppress_filters' => false do?

A Allows filters like 'posts_where' and 'posts_join' to modify the SQL query

B Prevents any filters from running on the query, improving performance

C Automatically caches the query results for faster repeated queries

D Disables pagination and returns all posts matching the query

💡 Hint

Think about how WordPress filters interact with queries.

Setting 'suppress_filters' to false allows WordPress filters to run on the query SQL, enabling plugins or themes to modify the query. The default true suppresses these filters.