Serving content dynamically using the directory parameter for GET requests - shelf package dart

Question

The code snippets below come from a server serving a get request

Server snippets

1)

  io.serve(handler, InternetAddress.LOOPBACK_IP_V4, 8080).then((server) {
    print('Listening on port 8080');
  }).catchError((error) => print(error));

2)

Router routes = new Router()
                      ..get('/newest', handler.handleNewest)
                      ..get('/anonymous', handler.handleAnonymousGetRequest)
                      ..post('/anonymous', handler.handleAnonymousPostRequest);

3)

shelf.Response handleNewest(shelf.Request request){
  print('got request for newest');
  return new shelf.Response.ok('sample content later fetched form db');
}

On a click event I also run this code in a client app.

void makeRequestNewest() {
  String path = 'http://127.0.0.1:8080/newest';
  HttpRequest.getString(path)
    .then((String newestContent){
    post_list.appendText(newestContent);
  })
  .catchError((Error error){
    post_list.appendText('an error occurred: ' + error.toString());
  });

unfortunately the getString is not successful. The catchError is run and results in an error occurred: Instance of '_XMLHttpRequestProgressEvent'. Also in the ToolsOutput command line of the Dart Editor I get [web] GET /newest => Could not find asset linkShepherdClient|web/newest.. This is correct, because that directory does not exist. I thought I can use the directory as a parameter to run the correct handler, and return the correct value in the .ok(), but it doesn't seem so. Does this mean I can not fetch the data from any source using the GET request, because it will always try to actually get it from this directory on the server?

Edit: code example using http package. (not working)

import 'package:http/http.dart' as http;
import 'package:http/browser_client.dart';

void makeRequestNewest() {
  String path = 'http://127.0.0.1:8080/newest';
  var client = new BrowserClient();
  client.get(path)
    .then((response){
    post_list.appendText('response status: ${response.statusCode}');
    post_list.appendText('Response body: ${response.body}');
  });
}

An answer using additional packages like the http package is also very welcome.

I don't really understand the question. A request isn't automatically mapped to a directory, this is what shelf_static is for. shelf_static maps the request to a file. If you have an Url path (route) which is not configured to be handled by shelf_static then you can return any content you want. — Günter Zöchbauer, May 17 '15 at 18:13
I was confused by the `[web] GET /newest => Could not find asset linkShepherdClient|web/newest.` message. Why otherwise wouldn't this `appendText` "sample content later fetched form db". — Lukasz, May 17 '15 at 18:23
`[web] GET /newest => Could not find asset linkShepherdClient|web/newest.` sounds like a pub serve message. Are you sure your request is actually getting to the server? Do you see `got request for newest` printed. Have you tried running `curl http://127.0.0.1:8080/newest` from the command line? Also worth adding a line `printRoutes(routes)` after you create your routes — Anders, May 17 '15 at 20:42
@Anders. This is what happened. I launched the client. Closed the browser window. The socket was still reserved. Then I tried to launch the server.Obviously the server couldn't start listening on the reserved socket and I didn't check it since the server worked fine before. Unfortunately the value appended by the `makeReqeustNewest()` function still isn't `sample content later fetched from db`, but the `an error occurred: Instance of '_XMLHttpRequestProgressEvent'`. That's why I leave the question open. — Lukasz, May 17 '15 at 21:22
@Anders If you are interested in taking a look at the whole code check out https://github.com/LukaszTrojanowski/linkShepherdClient and https://github.com/LukaszTrojanowski/linkShepherdServer — Lukasz, May 17 '15 at 21:29
I can't see anything obviously wrong from the code. I've you have established that the server is working as expected (e.g. via curl) then it must be something odd with the client. I have never used HttpRequest directly, but rather always via the http package. So can't help much with that — Anders, May 17 '15 at 22:01
@Anders I tried to apply the idea of using the http package but unfortunately unsuccessfully. Do you maybe have a github account where I could take a look at some of your code? — Lukasz, May 17 '15 at 22:35

score 0 · Accepted Answer · answered May 18 '15 at 19:30

I figured it out. I tried to access resources from a different domain (localhost:8080 and not localhost:8080/newest). This requres setting CORS header in the shelf.response. This is done for example like that

shelf.Response.ok('Message returned by handleNewest later fetched by db', headers: CORSHeader);

where CORSHeader is set to

const Map<String, String> CORSHeader = const {'Access-Control-Allow-Origin': '*'};

If you want to have access to the content from any domain. You can also replace the star with the domain you want to restrict the access to.

Serving content dynamically using the directory parameter for GET requests - shelf package dart

1 Answers1