Conduit HTTP Snippets

Hello, World
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class AppChannel extends ApplicationChannel {  
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  @override
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  Controller get entryPoint {
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    final router = Router();
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​
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    router.route("/hello_world").linkFunction((request) async {
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      return Response.ok("Hello, world!")
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        ..contentType = ContentType.TEXT;
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    });
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​
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    return router;
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  }
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}
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Route Variables
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class AppChannel extends ApplicationChannel {  
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  @override
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  Controller get entryPoint {
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    final router = Router();
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​
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    router.route("/variable/[:variable]").linkFunction((request) async {
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      return Response.ok({
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        "method": request.raw.method,
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        "path": request.path.variables["variable"] ?? "not specified"
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      });      
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    });
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​
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    return router;
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  }
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}
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Grouping Routes and Binding Path Variables
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class AppChannel extends ApplicationChannel {  
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  @override
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  Controller get entryPoint {
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    final router = Router();
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​
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    router
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      .route("/users/[:id]")
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      .link(() => MyController());
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​
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    return router;
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  }
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}
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​
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class MyController extends ResourceController {
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  final List<String> things = ['thing1', 'thing2'];
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​
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  @Operation.get()
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  Future<Response> getThings() async {
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    return Response.ok(things);
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  }
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​
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  @Operation.get('id')
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  Future<Response> getThing(@Bind.path('id') int id) async {
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    if (id < 0 || id >= things.length) {
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      return Response.notFound();
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    }
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    return Response.ok(things[id]);
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  }
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}
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Custom Middleware
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class AppChannel extends ApplicationChannel {  
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  @override
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  Controller get entryPoint {
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    final router = Router();
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​
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    router
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      .route("/rate_limit")
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      .link(() => RateLimiter())
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      .linkFunction((req) async => Response.ok({
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        "requests_remaining": req.attachments["remaining"]
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      }));
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​
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    return router;
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  }
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}
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​
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class RateLimiter extends RequestController {
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  @override
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  Future<RequestOrResponse> handle(Request request) async {
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    final apiKey = request.raw.headers.value("x-apikey");
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    final requestsRemaining = await remainingRequestsForAPIKey(apiKey);
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    if (requestsRemaining <= 0) {
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      return Response(429, null, null);
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    }
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​
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    request.addResponseModifier((r) {
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      r.headers["x-remaining-requests"] = requestsRemaining;
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    });
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​
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    return request;
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  }
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}
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Application-Wide CORS Allowed Origins
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class AppChannel extends ApplicationChannel {
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  @override
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  Future prepare() async {
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    // All controllers will use this policy by default
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    CORSPolicy.defaultPolicy.allowedOrigins = ["https://mywebsite.com"];
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  }
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​
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  @override
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  Controller get entryPoint {
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    final router = Router();
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​
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    router.route("/things").linkFunction((request) async {
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      return Response.ok(["Widget", "Doodad", "Transformer"]);
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    });
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​
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    return router;
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  }
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}
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Serve Files and Set Cache-Control Headers
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class AppChannel extends ApplicationChannel {
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  @override
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  Controller get entryPoint {
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    final router = Router();
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​
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    router.route("/files/*").link(() =>
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      FileController("web")
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        ..addCachePolicy(new CachePolicy(expirationFromNow: new Duration(days: 365)),
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          (path) => path.endsWith(".js") || path.endsWith(".css"))      
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    );
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​
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    return router;
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  }
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}
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Streaming Responses (Server Side Events with text/event-stream)
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class AppChannel extends ApplicationChannel {
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  final StreamController<String> controller = new StreamController<String>();  
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​
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  @override
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  Future prepare() async {
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    var count = 0;
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     Timer.periodic(new Duration(seconds: 1), (_) {
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      count ++;
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      controller.add("This server has been up for $count seconds\n");
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    });
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  }
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​
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  @override
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  Controller get entryPoint {
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    final router = new Router();
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​
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    router.route("/stream").linkFunction((req) async {
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      return Response.ok(controller.stream)
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          ..bufferOutput = false
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          ..contentType = new ContentType(
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            "text", "event-stream", charset: "utf-8");
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    });
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​
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    return router;
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  }
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}
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A websocket server
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class AppChannel extends ApplicationChannel {
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  List<WebSocket> websockets = [];
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​
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  @override
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  Future prepare() async {
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    // When another isolate gets a websocket message, echo it to
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    // websockets connected on this isolate.
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    messageHub.listen(sendBytesToConnectedClients);
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  }
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​
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  @override
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  Controller get entryPoint {
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    final router = Router();
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​
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    // Allow websocket clients to connect to ws://host/connect
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    router.route("/connect").linkFunction((request) async {
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      var websocket = await WebSocketTransformer.upgrade(request.raw);
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      websocket.listen(echo, onDone: () {
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        websockets.remove(websocket);
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      }, cancelOnError: true);
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      websockets.add(websocket);
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​
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      // Take request out of channel
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      return null;
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    });
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​
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    return router;
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  }
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​
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  void sendBytesToConnectedClients(List<int> bytes) {
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    websockets.forEach((ws) {
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      ws.add(bytes);
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    });
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  }
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​
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  void echo(List<int> bytes) {
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    sendBytesToConnectedClients(bytes);
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​
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    // Send to other isolates
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    messageHub.add(bytes);
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  }
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}
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Setting Content-Type and Encoding a Response Body
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class AppChannel extends ApplicationChannel {
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  final ContentType CSV = ContentType("text", "csv", charset: "utf-8");
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​
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  @override
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  Future prepare() async {
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    // CsvCodec extends dart:convert.Codec
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    CodecRegistry.defaultInstance.add(CSV, new CsvCodec());
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  }
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​
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  @override
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  Controller get entryPoint {
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    final router = Router();
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​
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    router.route("/csv").linkFunction((req) async {
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      // These values will get converted by CsvCodec into a comma-separated string
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      return Response.ok([[1, 2, 3], ["a", "b", "c"]])
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        ..contentType = CSV;
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    });
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​
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    return router;
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  }
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}
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Proxy a File From Another Server
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class AppChannel extends ApplicationChannel {
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  @override
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  Controller get entryPoint {
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    final router = Router();
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​
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    router.route("/proxy/*").linkFunction((req) async {
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      var fileURL = "https://otherserver/${req.path.remainingPath}";
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      var fileRequest = await client.getUrl(url);
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      var fileResponse = await req.close();
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      if (fileResponse.statusCode != 200) {
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        return new Response.notFound();
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      }
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​
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      // A dart:io.HttpResponse is a Stream<List<int>> of its body bytes.
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      return new Response.ok(fileResponse)
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        ..contentType = fileResponse.headers.contentType
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        // let the data just pass through because it has already been encoded
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        // according to content-type; applying encoding again would cause
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        // an issue
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        ..encodeBody = false;
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    });
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​
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    return router;
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  }
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}
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Conduit Snippets
Conduit ORM Snippets
Last modified 6mo ago
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Contents
Hello, World
Route Variables
Grouping Routes and Binding Path Variables
Custom Middleware
Application-Wide CORS Allowed Origins
Serve Files and Set Cache-Control Headers
Streaming Responses (Server Side Events with text/event-stream)
A websocket server
Setting Content-Type and Encoding a Response Body
Proxy a File From Another Server