Query parameters in Wordpress - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get the value of a query parameter named 'page'.

Wordpress

$page = $_GET[[1]];

Drag options to blanks, or click blank then click option'

A'user'

B'post'

C'page'

D'id'

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to use quotes around the parameter name.

Using $_POST instead of $_GET for query parameters.

In WordPress and PHP, query parameters are accessed via the $_GET superglobal array. To get the 'page' parameter, use $_GET['page'].

2fill in blank

medium

Complete the code to check if the 'category' query parameter exists.

Wordpress

if (isset($_GET[[1]])) {
    // do something
}

Drag options to blanks, or click blank then click option'

A'date'

B'category'

C'author'

D'tag'

Attempts:

3 left

💡 Hint

Common Mistakes

Checking $_POST instead of $_GET.

Using the wrong parameter name.

The isset() function checks if a variable is set and not null. To check if the 'category' query parameter exists, use isset($_GET['category']).

3fill in blank

hard

Fix the error in the code to safely get the 'author' query parameter or set it to 'guest' if missing.

Wordpress

$author = $_GET[[1]] ?? 'guest';

Drag options to blanks, or click blank then click option'

A'user'

B'admin'

C'name'

D'author'

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong parameter name.

Not using quotes around the parameter name.

The null coalescing operator ?? returns the left value if it exists and is not null; otherwise, it returns the right value. To get 'author' or default to 'guest', use $_GET['author'] ?? 'guest'.

4fill in blank

hard

Fill both blanks to create a query that gets posts filtered by 'tag' and ordered by 'date'.

Wordpress

$args = array(
    'tag' => $_GET[[1]],
    'orderby' => [2]
);

Drag options to blanks, or click blank then click option'

A'tag'

B'category'

C'date'

D'title'

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up 'tag' and 'category' keys.

Using a variable instead of a string for 'orderby'.

To filter posts by the 'tag' query parameter, use 'tag' => $_GET['tag']. To order posts by date, set 'orderby' => 'date'.

5fill in blank

hard

Fill all three blanks to build a WP_Query args array filtering by 'author', limiting posts to 5, and ordering by 'title'.

Wordpress

$args = array(
    'author_name' => $_GET[[1]],
    'posts_per_page' => [2],
    'orderby' => [3]
);

Drag options to blanks, or click blank then click option'

A'author'

B5

C'title'

D'category'

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'author' without quotes in the first blank.

Using a string instead of a number for posts_per_page.

Using a variable instead of a string for orderby.

To filter by author from query parameters, use $_GET['author']. Limit posts to 5 with 'posts_per_page' => 5. Order by title with 'orderby' => '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