Working with endpoints

Endpoints are the connection points to the server from the client. With Serverpod, you add methods to your endpoint, and your client code will be generated to make the method call. For the code to be generated, you need to place your endpoint in the endpoints directory of your server. Your endpoint should extend the Endpoint class. For methods to be generated, they need to return a typed Future, and its first argument should be a Session object. The Session object holds information about the call being made and provides access to the database.

import 'package:serverpod/serverpod.dart';

class ExampleEndpoint extends Endpoint {
  Future<String> hello(Session session, String name) async {
    return 'Hello $name';
  }
}

The above code will create an endpoint called example (the Endpoint suffix will be removed) with the single hello method. To generate the client-side code run serverpod generate in the home directory of the server.

On the client side, you can now call the method by calling:

var result = await client.example.hello('World');

The client is initialized like this:

// Sets up a singleton client object that can be used to talk to the server from
// anywhere in our app. The client is generated from your server code.
// The client is set up to connect to a Serverpod running on a local server on
// the default port. You will need to modify this to connect to staging or
// production servers.
var client = Client('http://$localhost:8080/')
  ..connectivityMonitor = FlutterConnectivityMonitor();

If you run the app in an Android emulator, the localhost parameter points to 10.0.2.2, rather than 127.0.0.1 as this is the IP address of the host machine. To access the server from a different device on the same network (such as a physical phone) replace localhost with the local ip address. You can find the local ip by running ifconfig (Linux/MacOS) or ipconfig (Windows).

Make sure to also update the publicHost in the development config to make sure the server always serves the client with the correct path to assets etc.

# your_project_server/config/development.yaml

apiServer:
  port: 8080
  publicHost: localhost # Change this line
  publicPort: 8080
  publicScheme: http
...

info

You can pass the --watch flag to serverpod generate to watch for changed files and generate code whenever your source files are updated. This is useful during the development of your server.

Passing parameters

There are some limitations to how endpoint methods can be implemented. Parameters and return types can be of type bool, int, double, String, UuidValue, Duration, DateTime, ByteData, or generated serializable objects (see next section). A typed Future should always be returned. Null safety is supported. When passing a DateTime it is always converted to UTC.

You can also pass List and Map as parameters, but they need to be strictly typed with one of the types mentioned above. For Map, the keys must be non-nullable strings. E.g., Map<String, int?> is valid, but Map<int, String> is not.

warning

While it's possible to pass binary data through a method call and ByteData, it is not the most efficient way to transfer large files. See our file upload interface. The size of a call is by default limited to 512 kB. It's possible to change by adding the maxRequestSize to your config files. E.g., this will double the request size to 1 MB:

maxRequestSize: 1048576

Return types

The return type must be a typed Future. Supported return types are the same as for parameters.