Request and response handling in Wordpress - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get a query parameter named 'id' from the URL in WordPress.

Wordpress

$id = get_query_var('[1]');

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

Apage

Bpost_id

Cid

Duser

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong parameter name like 'post_id' instead of 'id'.

Forgetting to put the parameter name as a string.

In WordPress, get_query_var('id') retrieves the 'id' parameter from the URL query.

2fill in blank

medium

Complete the code to send a JSON response with status 200 in WordPress.

Wordpress

wp_send_json_success([1]);

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

A'Success'

Barray('message' => 'Success')

Ctrue

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a string instead of an array.

Passing null which sends empty data.

wp_send_json_success() expects an array or object to send as JSON data.

3fill in blank

hard

Fix the error in the code to check if a POST request contains a 'name' parameter.

Wordpress

if (isset($_POST['[1]'])) {
    $name = sanitize_text_field($_POST['name']);
}

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

Aname

Busername

Cuser

Dfullname

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for a different key than the one used to read the value.

Not sanitizing the input after checking.

The isset check must match the key used to get the value from $_POST.

4fill in blank

hard

Fill both blanks to create a REST API endpoint callback that returns a JSON response with a message.

Wordpress

function my_api_callback() {
    return wp_send_json_[1](array('message' => '[2]'));
}

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

Asuccess

Berror

CHello World

DFailed

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'error' instead of 'success' for a positive response.

Putting an error message instead of a greeting.

Use wp_send_json_success to send a success response with a message.

5fill in blank

hard

Fill all three blanks to register a REST API route that accepts GET requests and uses a callback.

Wordpress

add_action('rest_api_init', function () {
    register_rest_route('myplugin/v1', '/data', array(
        'methods' => [1],
        'callback' => [2],
        'permission_callback' => [3]
    ));
});

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

A'POST'

B'GET'

C'__return_true'

Dmy_api_callback

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'POST' instead of 'GET' for the method.

Not using a valid permission callback function.

The route uses GET method, the callback function name, and a permission callback that always returns true.

Practice

1. In WordPress, which superglobal variable is commonly used to access data sent via an HTTP POST request?

easy

A. $_REQUEST

B. $_POST

C. $_GET

D. $GLOBALS

Solution

1. Step 1: Understand HTTP POST data handling

   Data sent by users through a POST request is stored in the $_POST superglobal in PHP.

2. Step 2: Differentiate from other superglobals

   $_GET holds URL query parameters, $_REQUEST combines GET, POST, and COOKIE but is less specific, and $GLOBALS holds all global variables.

3. Final Answer:

   $_POST -> Option B

4. Quick Check:

   POST data = $_POST [OK]

Hint: POST data is always in $_POST superglobal [OK]

Common Mistakes:

• Confusing $_GET with $_POST
• Using $_REQUEST without knowing its mixed content
• Assuming $GLOBALS holds request data

2. Which of the following is the correct way to send a JSON response in a WordPress REST API callback function?

easy

A. wp_send_json($data);

B. header('Content-Type: text/plain'); echo $data;

C. echo json_encode($data);

D. return new WP_REST_Response($data, 200);

Solution

1. Step 1: Understand WordPress REST API callback requirements

   REST API callbacks should return a WP_REST_Response, array, or WP_Error. The framework handles headers, JSON encoding, and status.

2. Step 2: Compare other options

   wp_send_json($data); sends JSON and exits with wp_die(), suitable for AJAX but bypasses REST processing/filters. echo json_encode($data); outputs JSON without headers or exit. header('Content-Type: text/plain'); echo $data; wrong type.

3. Final Answer:

   return new WP_REST_Response($data, 200); -> Option D

4. Quick Check:

   Return WP_REST_Response [OK]

Hint: Return WP_REST_Response for REST API JSON response [OK]

Common Mistakes:

• Using wp_send_json() (intended for AJAX handlers)
• Using echo without proper headers and exit
• Sending wrong content type header

3. Consider this WordPress REST API callback function:

function get_custom_data(\WP_REST_Request $request) {
  $param = $request->get_param('id');
  if ($param === '42') {
    return ['message' => 'Found'];
  }
  return new WP_Error('not_found', 'ID not found', ['status' => 404]);
}

What will be the HTTP status code if the request URL includes ?id=42?

medium

A. 200

B. 404

C. 500

D. 302

Solution

1. Step 1: Analyze the parameter check

   The function checks if id equals '42'. If yes, it returns an array with message 'Found'.

2. Step 2: Understand default REST API response codes

   Returning an array results in a 200 OK status. Returning WP_Error sets the error status (404 here).

3. Final Answer:

   200 -> Option A

4. Quick Check:

   Valid data returns 200 OK [OK]

Hint: Array return = 200 OK; WP_Error return = error code [OK]

Common Mistakes:

• Assuming WP_Error always returns 200
• Confusing string '42' with integer 42
• Ignoring default REST API status codes

4. You wrote this WordPress REST API endpoint callback:

function my_callback(\WP_REST_Request $request) {
  $data = $request->get_param('data');
  wp_send_json_success($data);
  echo 'Done';
}

What is the problem with this code?

medium

A. The echo statement after wp_send_json_success() will never run

B. wp_send_json_success() does not send JSON

C. get_param() cannot retrieve 'data' parameter

D. Missing return statement causes error

Solution

1. Step 1: Understand wp_send_json_success behavior

   This function sends JSON response and calls exit(), stopping further code execution.

2. Step 2: Analyze code after wp_send_json_success

   The echo 'Done'; line is unreachable because the script exits before it.

3. Final Answer:

   The echo statement after wp_send_json_success() will never run -> Option A

4. Quick Check:

   wp_send_json_success() exits script [OK]

Hint: Code after wp_send_json_success() is unreachable [OK]

Common Mistakes:

• Expecting code after wp_send_json_success() to run
• Confusing get_param() usage
• Thinking wp_send_json_success() returns data instead of exiting

5. You want to create a WordPress REST API endpoint that accepts a POST request with a JSON body containing a 'name' field. Which sequence correctly handles the request and sends a JSON response with a greeting message?

hard

A. Use $request->get_body_params()['name'] to get 'name', then return ['greeting' => 'Hello ' . $name].

B. Use $_POST['name'] directly, then echo JSON encoded greeting and exit.

C. Use $request->get_json_params()['name'] to get 'name', then return new WP_REST_Response(['greeting' => 'Hello ' . $name], 200).

D. Use file_get_contents('php://input') to read JSON body, then use wp_send_json() to send response.

Solution

1. Step 1: Retrieve JSON body parameters properly

   In WordPress REST API, $request->get_json_params() safely parses JSON body data.

2. Step 2: Return a proper REST response object

   Returning WP_REST_Response with data and status code is the recommended way to send structured responses.

3. Step 3: Evaluate other options

   A uses get_body_params() which checks form data ($_POST), empty for JSON body POSTs. C uses $_POST['name'] directly, same issue. D manually reads input bypassing framework helpers and uses wp_send_json() which exits.

4. Final Answer:

   Use $request->get_json_params()['name'] and return WP_REST_Response -> Option C

5. Quick Check:

   Use get_json_params() + WP_REST_Response for JSON POST [OK]

Hint: Use get_json_params() for JSON body in REST API [OK]

Common Mistakes:

• Using $_POST or get_body_params for JSON body data
• Not decoding JSON body properly
• Returning raw arrays instead of WP_REST_Response