Create custom RESTful API endpoint with JSON output in Drupal 7

RESTful API endpoints in Drupal can allow you to expose the content of Drupal 7 website to other external resources. These endpoints can be used for fetching data with an AJAX call or simply a web service.

For making complex RESTful web services in Drupal 7, Services module is the best option to go for but if you looking for a simple endpoint in Drupal 7, which outputs JSON response, then going with a custom solution will be the best bet.

Create API endpoint with JSON response in Drupal 7

To create a simple API endpoint in Drupal to serve a JSON put you need to create a custom callback

/**
 * Implements hook_menu().
 */
function mymodule_menu() {
  $items['api/mymodule'] = array(
    'access callback' => true,
    'page callback' => 'mymodule_json',
    'delivery callback' => 'drupal_json_output',
  );

  return $items;
}

A noticeable point in this callback is the "delivery callback" argument which runs the output through drupal_json_output function.

/**
 * Callback function to return the data.
 */
function mymodule_json() {
  $data = ['cat', 'dog', 'mouse', 'elephant'];

  return $data;
}

Now if you navigate to the callback url 'api/mymodule' to see the output then you will see the following result

[
 "cat",
 "dog",
 "mouse",
 "elephant",
]

Now you can see that this output is exposed as a JSON and can be consumed by other platforms or an AJAX callback to consume data.

The same approach can be used to expose a node or a user as a JSON output.