Query parameters in Wordpress - Mini Project: Build & Apply

WordPress Query Parameters

📖 Scenario: You are building a WordPress site that shows a list of blog posts. You want to control which posts appear by using query parameters in your code.

🎯 Goal: Create a WordPress query using query parameters to display posts from a specific category and limit the number of posts shown.

📋 What You'll Learn

Create an array called $args with specific query parameters

Add a variable $posts_per_page to control how many posts to show

Use WP_Query with the $args array to get posts

Complete the loop to display the post titles

💡 Why This Matters

🌍 Real World

WordPress developers often need to customize which posts appear on a page by using query parameters to filter posts by category, status, or other criteria.

💼 Career

Understanding WP_Query and query parameters is essential for WordPress theme and plugin developers to create dynamic and customized content displays.

1

Create the query parameters array

Create an array called $args with these exact entries: 'category_name' => 'news' and 'post_status' => 'publish'.

Wordpress

# Create the query parameters array
# Your code here

Hint

Use array() to create $args with keys and values exactly as shown.

2

Add a posts per page variable

Add a variable called $posts_per_page and set it to 5. Then add this to the $args array with the key 'posts_per_page'.

Wordpress

$args = array(
    'category_name' => 'news',
    'post_status' => 'publish'
);
# Add $posts_per_page variable and add it to $args
# Your code here

Hint

Define $posts_per_page as 5 and add it to $args with the key 'posts_per_page'.

3

Create the WP_Query object

Create a variable called $query and set it to a new WP_Query object using the $args array.

Wordpress

$args = array(
    'category_name' => 'news',
    'post_status' => 'publish'
);
$posts_per_page = 5;
$args['posts_per_page'] = $posts_per_page;
# Create WP_Query object with $args
# Your code here

Hint

Use new WP_Query($args) to create the query object.

4

Complete the loop to display post titles

Write a while loop that runs while $query->have_posts() is true. Inside the loop, call $query->the_post() and then output the post title using the_title().

Wordpress

$args = array(
    'category_name' => 'news',
    'post_status' => 'publish',
    'posts_per_page' => 5
);
$query = new WP_Query($args);
# Complete the loop to display post titles
# Your code here

Hint

Use a while loop with $query->have_posts(), call $query->the_post() inside, then output the title with the_title().

Practice

1. What is the main purpose of query parameters in WordPress when used with WP_Query?

easy

A. To create new user accounts automatically

B. To change the WordPress theme dynamically

C. To add custom CSS styles to posts

D. To filter and retrieve specific posts based on conditions like category or author

Solution

1. Step 1: Understand the role of query parameters

   Query parameters are used to specify conditions for retrieving posts, such as filtering by category or author.

2. Step 2: Identify the correct purpose in WordPress context

   They do not change themes, add styles, or create users; they filter content queries.

3. Final Answer:

   To filter and retrieve specific posts based on conditions like category or author -> Option D

4. Quick Check:

   Query parameters filter posts = D [OK]

Hint: Query parameters filter posts by conditions like category or author [OK]

Common Mistakes:

• Thinking query parameters change themes
• Confusing query parameters with styling or user management
• Assuming query parameters create new content

2. Which of the following is the correct way to query posts from category with ID 5 using WP_Query?

easy

A. $query = new WP_Query(array('category' => 5));

B. $query = new WP_Query(array('cat' => 5));

C. $query = new WP_Query(array('category_name' => 5));

D. $query = new WP_Query(array('category_id' => 5));

Solution

1. Step 1: Recall correct parameter for category ID

   The correct parameter to filter by category ID is 'cat', not 'category', 'category_name', or 'category_id'.

2. Step 2: Verify syntax correctness

   $query = new WP_Query(array('cat' => 5)); uses 'cat' with the ID 5 correctly in an array for WP_Query.

3. Final Answer:

   $query = new WP_Query(array('cat' => 5)); -> Option B

4. Quick Check:

   Category ID filter uses 'cat' = C [OK]

Hint: Use 'cat' key for category ID in WP_Query parameters [OK]

Common Mistakes:

• Using 'category' instead of 'cat' for category ID
• Passing category ID as 'category_name'
• Using 'category_id' which is invalid

3. What will be the result of this code snippet?

$args = array('author' => 3, 'posts_per_page' => 2);
$query = new WP_Query($args);
while ($query->have_posts()) {
  $query->the_post();
  echo get_the_title() . ', ';
}

medium

A. It will display the titles of the latest 2 posts by author with ID 3

B. It will display all posts by author with ID 3

C. It will cause a syntax error because 'author' is invalid

D. It will display 2 posts from any author

Solution

1. Step 1: Analyze query parameters

   'author' => 3 filters posts by author ID 3, 'posts_per_page' => 2 limits results to 2 posts.

2. Step 2: Understand loop output

   The loop outputs the titles of these posts separated by commas.

3. Final Answer:

   It will display the titles of the latest 2 posts by author with ID 3 -> Option A

4. Quick Check:

   Author filter + limit 2 posts = B [OK]

Hint: Author ID filters posts; posts_per_page limits number shown [OK]

Common Mistakes:

• Assuming 'author' is invalid parameter
• Thinking it shows all posts by author ignoring limit
• Believing it shows posts from any author

4. Identify the error in this query parameter usage:

$args = array('category' => 'news', 'posts_per_page' => 5);
$query = new WP_Query($args);

medium

A. 'category' should be 'category_name' to filter by category slug

B. 'posts_per_page' must be a string, not a number

C. 'category' should be 'cat' with category slug

D. No error, this code works correctly

Solution

1. Step 1: Check parameter for category slug

   To filter by category slug (like 'news'), the correct parameter is 'category_name', not 'category'.

2. Step 2: Validate other parameters

   'posts_per_page' accepts a number, so that part is correct.

3. Final Answer:

   'category' should be 'category_name' to filter by category slug -> Option A

4. Quick Check:

   Category slug filter uses 'category_name' = A [OK]

Hint: Use 'category_name' for slug, 'cat' for ID in queries [OK]

Common Mistakes:

• Using 'category' instead of 'category_name' for slug
• Thinking 'posts_per_page' must be string
• Confusing 'cat' with slug instead of ID

5. You want to display posts that belong to category ID 4 or category ID 7 using WP_Query. Which query parameter array will correctly achieve this?

hard

A. array('category_name' => '4,7')

B. array('cat' => '4,7')

C. array('category__in' => array(4, 7))

D. array('cat' => array(4, 7))

Solution

1. Step 1: Understand how to query multiple categories

   To query posts in multiple categories by ID, use 'category__in' with an array of IDs.

2. Step 2: Evaluate each option

   array('cat' => '4,7') uses a string with comma which is invalid for 'cat'. array('category_name' => '4,7') uses 'category_name' with numbers which expects slugs. array('cat' => array(4, 7)) uses 'cat' with an array which is invalid.

3. Final Answer:

   array('category__in' => array(4, 7)) -> Option C

4. Quick Check:

   Multiple category IDs use 'category__in' with array = A [OK]

Hint: Use 'category__in' with array for multiple category IDs [OK]

Common Mistakes:

• Passing multiple IDs as comma string to 'cat'
• Using 'category_name' with numeric IDs
• Passing array to 'cat' which expects single ID