Serve a JSON API

1 min read

Save this as app.dream. It accepts a name from the URL and returns a JSON greeting.

import system;
import system.json;
import system.webapi;

@json
class Greeting {
    public message: string;

    public constructor(message: string) {
        this.message = message;
    }
}

@router("")
class Routes {
    @get("/hello/{name}")
    public static fun hello(@path name: string): Greeting {
        return Greeting("Hello, " + name);
    }
}

async fun main(): void {
    let app = WebApp();
    app.include_router(Routes.router()).unwrap();
    app.run("127.0.0.1", 8000).await.unwrap();
}

Run dream run app.dream, then open http://127.0.0.1:8000/hello/Dream. The response is {"message":"Hello, Dream"} with the application/json content type. Open /docs to try the endpoint interactively. Stop the server with Ctrl+C.

@path reads the URL parameter. @json lets the handler return a typed object. Configuration and startup return Result; this small example uses unwrap to report failures immediately. An application that needs recovery should inspect those results and handle the errors before accepting requests.

Continue with validated models, dependencies, or the complete service example.