read method
override
GET /:id Fetch one resource, by its ID
Implementation
@override
Future<Map<String, dynamic>> read(String id,
[Map<String, dynamic> params]) async {
var found = await collection.document(id);
if (found == null) {
throw AngelHttpException.notFound(message: 'No record found for ID $id');
}
var doc = await found.get();
return _mapWithId(doc);
}