dvDevBackendUrl function

String dvDevBackendUrl(
  1. String configured, {
  2. required Uri page,
})

configured with a loopback host replaced by the host page was served from.

dartvel dev configures the backend as localhost, which is right on the machine running it and wrong everywhere else: a phone that opened the preview at http://10.0.0.7:8080 has no backend on its own localhost, so every call failed while the page itself loaded. The page's own host is the machine that served it, which is the machine running the backend.

Only for a loopback backend and a page served over http(s) from somewhere else. A deployed backend is never rewritten.

Implementation

String dvDevBackendUrl(String configured, {required Uri page}) {
  final Uri? backend = Uri.tryParse(configured);
  if (backend == null || !_isLoopback(backend.host)) return configured;
  if (page.scheme != 'http' && page.scheme != 'https') return configured;
  if (page.host.isEmpty || _isLoopback(page.host)) return configured;
  return backend.replace(host: page.host).toString();
}