{"id":12,"date":"2008-12-10T15:50:25","date_gmt":"2008-12-10T20:50:25","guid":{"rendered":"http:\/\/www.danielansari.com\/wordpress\/?p=12"},"modified":"2016-10-10T12:31:24","modified_gmt":"2016-10-10T17:31:24","slug":"how-to-use-the-rest-api-in-elgg-11","status":"publish","type":"post","link":"http:\/\/www.danielansari.com\/wordpress\/2008\/12\/how-to-use-the-rest-api-in-elgg-11\/","title":{"rendered":"How to use the REST API in Elgg 1.1"},"content":{"rendered":"

The Elgg<\/a> documentation describes the REST API<\/a> rather superficially, yet provides no samples, and is now inaccurate for the recent versions of Elgg.<\/p>\n

After a minor modification to your .htaccess file, using the REST API is very simple, and, in many cases, avoids the need to create individual files in your Elgg root directory to provide custom functionality.<\/p>\n

First, let’s look at how your API method would be called:<\/p>\n

http:\/\/localhost:8080\/elgg\/pg\/api\/rest?method=login&username=dansari&password=apples<\/code><\/p>\n

Let me explain technically what’s going on first. Any API calls in Elgg are handled by a page handler,<\/em> i.e.,<\/em> when the HTTP request begins with \/pg\/...<\/code>, the .htaccess (containing mod_rewrite<\/code> rules) tells Apache to use the Elgg file engine\/handlers\/pagehandler.php<\/code> to handle the request. Elgg then determines which page handler to use, and invokes it. The REST API is known as an “API endpoint”. In this case, because the next part of the URL is rest<\/code>, the API page handler passes control to the file services\/api\/rest.php<\/code>.<\/p>\n

The problem with the .htaccess that ships with Elgg is that it would cause the page handler to be invoked as pagehandler.php?handler=api&page=rest<\/code>, discarding the querystring entirely. services\/api\/rest.php<\/code> actually expects the method parameters to be in the querystring, so to get this to work, we simply change the following line in .htaccess:<\/p>\n

RewriteRule ^pg\\\/([A-Za-z\\_\\-]+)\\\/(.*)$\r\nengine\/handlers\/pagehandler.php?handler=$1&page=$2<\/pre>\n
to this:<\/p>\n
RewriteRule ^pg\\\/([A-Za-z\\_\\-]+)\\\/(.*)$\r\nengine\/handlers\/pagehandler.php?handler=$1&page=$2 [QSA]<\/pre>\n
Here is the code for a sample REST method, which would be implemented via a plugin. For this example, the following file is located at mod\/rest_login\/start.php<\/code> (NB<\/em> I had to put a space character before the ?php<\/code> in line 1 for WordPress to render this listing):<\/p>\n\n
    \n
  1. <<\/span> ?php<\/code><\/li>\n
  2.  <\/li>\n
  3. function<\/span> rest_login_init(<\/span>)<\/span> {<\/span><\/code><\/li>\n
  4. expose_function(<\/span>'login'<\/span>,<\/span> 'rest_login_handler'<\/span>,<\/span> array<\/span><\/a>(<\/span><\/code><\/li>\n
  5. "username"<\/span> =><\/span> array<\/span><\/a>(<\/span>"type"<\/span> =><\/span> "string"<\/span>)<\/span>,<\/span><\/code><\/li>\n
  6. "password"<\/span> =><\/span> array<\/span><\/a>(<\/span>"type"<\/span> =><\/span> "string"<\/span>)<\/span><\/code><\/li>\n
  7. )<\/span>,<\/span> ""<\/span>,<\/span> "GET"<\/span>,<\/span> false<\/span>,<\/span> true<\/span>)<\/span>;<\/span><\/code><\/li>\n
  8. }<\/span><\/code><\/li>\n
  9.  <\/li>\n
  10. function<\/span> rest_login_handler(<\/span>$username<\/span>,<\/span> $password<\/span>)<\/span> {<\/span><\/code><\/li>\n
  11. $persistent<\/span> =<\/span> "1"<\/span>;<\/span><\/code><\/li>\n
  12. $result<\/span> =<\/span> false<\/span>;<\/span><\/code><\/li>\n
  13. if<\/span> (<\/span>!<\/span>empty<\/span><\/a>(<\/span>$username<\/span>)<\/span> &&<\/span> !<\/span>empty<\/span><\/a>(<\/span>$password<\/span>)<\/span>)<\/span> {<\/span><\/code><\/li>\n
  14. if<\/span> (<\/span>$user<\/span> =<\/span> authenticate(<\/span>$username<\/span>,<\/span>$password<\/span>)<\/span>)<\/span> {<\/span><\/code><\/li>\n
  15. $result<\/span> =<\/span> login(<\/span>$user<\/span>,<\/span> $persistent<\/span>)<\/span>;<\/span><\/code><\/li>\n
  16. }<\/span><\/code><\/li>\n
  17. }<\/span><\/code><\/li>\n
  18. return<\/span> $result<\/span>;<\/span><\/code><\/li>\n
  19. }<\/span><\/code><\/li>\n
  20.  <\/li>\n
  21. \/\/ Add the plugin's init function to the system's init event<\/span><\/code><\/li>\n
  22. register_elgg_event_handler(<\/span>'init'<\/span>,<\/span>'system'<\/span>,<\/span>'rest_login_init'<\/span>)<\/span>;<\/span><\/code><\/li>\n
  23.  <\/li>\n
  24. ?><\/span><\/code><\/li>\n<\/ol>\n
    The important differences between what is stated in the Elgg documentation and here are:<\/p>\n