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Asynchronous I/O that doesn’t get in your way, written in D

Function registerRestInterface

Registers a server matching a certain REST interface.

URLRouter registerRestInterface(TImpl) (
  URLRouter router,
  TImpl instance,
  RestInterfaceSettings settings = null

URLRouter registerRestInterface(TImpl) (
  URLRouter router,
  TImpl instance,
  MethodStyle style

URLRouter registerRestInterface(TImpl) (
  URLRouter router,
  TImpl instance,
  string url_prefix,
  MethodStyle style = MethodStyle.lowerUnderscored

Servers are implementation of the D interface that defines the RESTful API. The methods of this class are invoked by the code that is generated for each endpoint of the API, with parameters and return values being translated according to the rules documented in the module documentation.

A basic 'hello world' API can be defined as follows:

interface APIRoot {
    string get();

class API : APIRoot {
    override string get() { return "Hello, World"; }

void main()
    // -- Where the magic happens --
    router.registerRestInterface(new API());
    // GET and 'Hello, World' will be replied
    listenHTTP("", router);


As can be seen here, the RESTful logic can be written inside the class without any concern for the actual HTTP representation.

Return value

By default, all methods that return a value send a 200 (OK) status code, or 204 if no value is being returned for the body.

Non-success: In the cases where an error code should be signaled to the user, a HTTPStatusException can be thrown from within the method. It will be turned into a JSON object that has a statusMessage field with the exception message. In case of other exception types being thrown, the status code will be set to 500 (internal server error), the statusMessage field will again contain the exception's message, and, in debug mode, an additional statusDebugMessage field will be set to the complete string representation of the exception (Exception.toString), which usually contains a stack trace useful for debugging.

Returning data

To return data, it is possible to either use the return value, which will be sent as the response body, or individual ref/out parameters can be used. The way they are represented in the response can be customized by adding @viaBody/@viaHeader annotations on the parameter declaration of the method within the interface.

In case of errors, any @viaHeader parameters are guaranteed to be set in the response, so that applications such as HTTP basic authentication can be implemented.

Template Params

TImpl = Either an interface type, or a class that derives from an interface. If the class derives from multiple interfaces, the first one will be assumed to be the API description and a warning will be issued.


router The HTTP router on which the interface will be registered
instance Server instance to use
settings Additional settings, such as the MethodStyle or the prefix

See Also

RestInterfaceClient class for an automated way to generate the matching client-side implementation.


This is a very limited example of REST interface features. Please refer to the "rest" project in the "examples" folder for a full overview.

All details related to HTTP are inferred from the interface declaration.

interface IMyAPI
	// GET /api/greeting
	@property string greeting();

	// PUT /api/greeting
	@property void greeting(string text);

	// POST /api/users
	void addNewUser(string name);

	// GET /api/users
	@property string[] users();

	// GET /api/:id/name
	string getName(int id);

	// GET /some_custom_json
	Json getSomeCustomJson();

// vibe.d takes care of all JSON encoding/decoding
// and actual API implementation can work directly
// with native types

class API : IMyAPI
	private {
		string m_greeting;
		string[] m_users;

	@property string greeting() { return m_greeting; }
	@property void greeting(string text) { m_greeting = text; }

	void addNewUser(string name) { m_users ~= name; }

	@property string[] users() { return m_users; }

	string getName(int id) { return m_users[id]; }

	Json getSomeCustomJson()
		Json ret = Json.emptyObject;
		ret["somefield"] = "Hello, World!";
		return ret;

// actual usage, this is usually done in app.d module
// constructor

void static_this()
	import vibe.http.server, vibe.http.router;

	auto router = new URLRouter;
	router.registerRestInterface(new API());
	listenHTTP(new HTTPServerSettings(), router);

Sönke Ludwig, Михаил Страшун, Mathias 'Geod24' Lang


© 2012-2018 Sönke Ludwig


Subject to the terms of the MIT license, as written in the included LICENSE.txt file.