Handler

Event handler define application logic.

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After creating an app instance, you can start defining your application logic using event handlers. An event handler is a function that receive an Event instance and returns a response. You can compare it to controllers in other frameworks.

Defining event handlers

To define an event handler you just need to create a function that accepts an Event object and can return anything:

String handler(Event event) {
    return 'Response';
}

The callback function can be sync or async:

Future<String> handler(Event event) async {
    return 'Response';
}

Responses Types

Values returned from event handlers are automatically converted to responses. It can be:

• You can return an arbitrary object (e.g. Map, List) or an object with a toJson() method, it will be stringified and sent with default application/json content-type.
• String/num/bool - Sent as-is using default text/plain content-type.
• null/void - Spry with end response with 204 - No Content status code.
• Response
• Stream<Uint8List>

Any of above values could also be wrapped in a FutureOr. This means that you can return a FutureOr from your event handler and Spry will wait for it to resolve before sending the response.

Middleware

app.use((event, next) {
    final res = next(event);
    print('after');

    return res;
});