API:Cross-site requests

If an external site needs to make an API call against a MediaWiki site, it must use CORS (preferred) or JSONP (older, less secure).

CORS usage

If a user script or gadget is used to make an API call against a site within the same wiki family , it must use a MediaWiki module that uses CORS under the hood: mediawiki.ForeignApi . This is the way to go for instance, if a script on the English Wikipedia needs to check image information on Commons.

The MediaWiki API requires that the origin be supplied as a query string parameter. If the CORS request is authenticated, its value must be the site from which the request originates, which is matched against the Origin header required by the CORS protocol. Note that this parameter must be included in any pre-flight request, and so should be included in the query string portion of the request URI even for POST requests.

When the origin parameter is supplied and the request does not return a successful CORS response, MediaWiki≥1.30 will return a MediaWiki-CORS-Rejection header with a brief reason for the failure, e.g. in case of mismatched origin or unsupported headers in a Access-Control-Request-Headers request header.

Unauthenticated CORS Requests

Unauthenticated CORS requests may be made from any origin by setting the origin request parameter to *. In this case MediaWiki will include the Access-Control-Allow-Credentials: false header in the response and will process the request as if logged out.

Example

GET request

Get the names of the first three images from Wikimedia Commons.

api.php?action=query&list=allimages&ailimit=3&format=json&origin=* [try in ApiSandbox]

Sample code

var apiEndpoint = "https://commons.wikimedia.org/w/api.php";
var params = "action=query&list=allimages&ailimit=3&format=json";

/**
 * Send the request to get the images
 */
fetch(apiEndpoint + "?" + params + "&origin=*")
    .then(function(response){return response.json();})
    .then(function(response) {
          var allimages = response.query.allimages; // Process the output to get the image names
          Object.keys(allimages).forEach(function(key) {
               console.log(allimages[key].name);
          });
     });

Response

!!!!!_Mdina_Fortifications,_Ditch,_Bridge_and_Main_Gate.jpg
!!!!_Mdina_buildings_!!!!.jpg
!!!!_Palazzo_Dorell_ancillary_building.jpg

Authenticated CORS Requests

To make an authenticated CORS request, the remote wiki's $wgCrossSiteAJAXdomains setting must be set to allow the origin site. If the CORS origin check passes, MediaWiki will include the Access-Control-Allow-Credentials: true header in the response, so authentication cookies may be sent.

Manual:CORS contains more instructions and examples on how to handle CORS requests in JavaScript.

JSONP usage

The API's format=json accepts a callback parameter, whose value is a JavaScript function which the JSON result will be wrapped in. This may be used to call the API on a remote site by dynamically adding ‎<script> tags to the document.

Using JSONP weakens the security of your origin site because, as described above, API responses are executed as JavaScript code. If an attacker compromises the remote site, they can use their access to run arbitrary JavaScript code in your users' browsers, within the context of your site. It is recommended to use CORS instead.

Any JSONP requests will be processed as if logged out (i.e as an anonymous user), even after logging in to the remote wiki.

Example

GET request

Get the titles of three random pages from English Wikipedia.

api.php?action=query&list=random&rnlimit=3&format=json&callback=my_callback [try in ApiSandbox]

Sample code

var apiEndpoint = "https://en.wikipedia.org/w/api.php";
var params = "action=query&list=random&rnlimit=3&format=json";

/**
 * The function to wrap the result
 */
window.my_callback = function (response) {
    var pages = response.query.random; // Process the output to get the titles
    Object.keys(pages).forEach(function(key) {
        console.log(pages[key].title);
    });
};

var scriptTag = document.createElement("script"); // Dynamically create a "script" tag
scriptTag.src = apiEndpoint + "?" + params + "&callback=my_callback"; // Point to the query string

document.body.appendChild(scriptTag); // Add the script tag to the document

Response

Kache Aye Shoi
Talk:Sarbka, Wągrowiec County
Category:Nakhon Ratchasima Province

See also

• Extension:CentralAuth/API#centralauthtoken