How do I return JSON data?

Question

Is this the correct way to return json data. If not, how should it be accomplished? I would like to return the data back to car.module.

card.module

drupal_add_js('jQuery(document).ready(function () {

  currentRequest = $.ajax({
  timeout:0,
  cache: false,
  url: pageUrl,
  dataType: "json",
  type: "GET",
  success: function(data) {
    $("#edit-field-currency-type-und-0-value").val(data.currency);            
  }

});

AJAX request module

$items['mccurr/%'] = array(
  'title' => '', 
  'page callback' => 'ajax_currency_type', 
  'access arguments' => array('access content'), 
  'page arguments' => array(1),
  'type' => MENU_SUGGESTED_ITEM,
);

function ajax_currency_type($ccode) {
 drupal_add_http_header('Content-Type', 'application/javascript; utf-8');
  $query = "SELECT countries_country.currency 
    FROM countries_country
    WHERE countries_country.iso2 = '".$ccode."'";

  $data = db_query($query);

  return drupal_json_encode($data);
}

Answer 1

To return $data in json format using Drupal-7's page callback output, you should return through :

drupal_json_output($data);

in your page callback function. For more ref : http://api.drupal.org/api/drupal/includes!common.inc/function/drupal_json_output/7

Note : in your javascript in car.module, var pageUrl seems undefined. Make sure it is defined.

Answer 2

You really should never pass unsanitized input anywhere, see "Bobby Tables".

Drupal has the facility to escape database parameters like this;

$query = "SELECT countries_country.currency 
    FROM countries_country
    WHERE countries_country.iso2 = :ccode";

$data = db_query($query, array(':ccode' => $ccode));

Note that you'll also need to ->fetchAll() else you're just returning a database object.

Answer 3

I've recently found the REST/JSON module that once enabled exposes APIs to list nodes and commends, to log in / log out users, and to create entities with REST calls that read and output JSON data.

It doesn't require any further code or configuration.

This module is unsupported due to a security issue the maintainer didn't fix, since June 8, 2016.