Gebweb hello world

A minimal Gebweb application: one controller with a few

Path

gebweb/examples/hello.gb

Category

General

decorated handlers, automatic OpenAPI 3.1 generation, SwaggerUI at

/docs, and an HTTP exception that round-trips through the

framework as an RFC 9457 problem document.

Run:

geblang examples/hello.gb

Then open http://127.0.0.1:8080/ in a browser or curl, and

http://127.0.0.1:8080/docs for the auto-generated SwaggerUI page.

Source

import gebweb;
import io;

class GreetingDTO {
    string name;
    ?string greeting;
}

class HelloController {
    /* In-memory store so the POST/GET pair has something to look at. */
    dict<string, dict<string, any>> greetings;

    func HelloController() {
        this.greetings = {};
    }

    @Get("/")
    @Summary("Service banner")
    func index(): dict<string, any> {
        return {"service": "gebweb-hello", "version": "0.1.0"};
    }

    @Get("/hello/{name}")
    @Summary("Greet someone")
    func hello(string name, ?string lang): dict<string, any> {
        string g = "Hello";
        if (lang != null) {
            let normalised = (lang as string).lower();
            if (normalised == "fr") { g = "Bonjour"; }
            if (normalised == "es") { g = "Hola"; }
            if (normalised == "de") { g = "Hallo"; }
        }
        return {"message": g + ", " + name + "!"};
    }

    @Post("/greetings")
    @Summary("Store a custom greeting for a name")
    func store(GreetingDTO body): dict<string, any> {
        string g = "Hello";
        if (body.greeting != null) {
            g = body.greeting as string;
        }
        dict<string, any> entry = {"name": body.name, "greeting": g};
        this.greetings[body.name] = entry;
        return entry;
    }

    @Get("/greetings/{name}")
    @Summary("Look up a stored greeting; 404 if missing")
    func lookup(string name): dict<string, any> {
        if (!this.greetings.contains(name)) {
            throw gebweb.notFound("no greeting for '" + name + "'");
        }
        return this.greetings[name];
    }
}

let app = gebweb.setInfo(gebweb.app([HelloController()]), {
    "title": "Gebweb Hello",
    "version": "0.1.0",
    "description": "A minimal Gebweb application demonstrating decorator-driven routing, typed parameter binding, OpenAPI 3.1 generation, SwaggerUI, and HTTP exceptions.",
});

io.println("Gebweb hello world listening on http://127.0.0.1:8080");
io.println("Routes:");
for (route in gebweb.routes(app)) {
    io.println("  " + (route["method"] as string) + " " + (route["path"] as string));
}
io.println("  GET /openapi.json");
io.println("  GET /docs");

gebweb.serve(app, "127.0.0.1:8080");