Flutter: Retrieve associated object from Future in FutureBuilder widget - flutter

Question

I am fetching the user 'event manager id' data coming from a future of the object 'event'. I would like now to fetch a user using that id to display his name next the event. However, my FutureBuilder widget only takes into account one future (Event) and I am not able to retrieve that user's name based on that event since my fetchUser method will only return Future objects.
Any help is greatly appreciated.
Here's the FutureBuilder widget:
body: new FutureBuilder(
future: events,
builder: (BuildContext context, AsyncSnapshot<List> snapshot) {
List<Event> availableEvents = snapshot.data;
if (!snapshot.hasData) return CircularProgressIndicator();
return new ListView.builder(
scrollDirection: Axis.vertical,
padding: new EdgeInsets.all(6.0),
itemCount: availableEvents.length,
itemBuilder: (BuildContext context, int index) {
user = fetchUserbyId( // Here, user is of type Future<user> and I cannot retrieve info such as the name of that user
(availableEvents[index].managerId).toString());
return new Container(
margin: new EdgeInsets.only(bottom: 6.0),
padding: new EdgeInsets.all(6.0),
color: Colors.white,
child: Column(
children: <Widget>[
new Text('${availableEvents[index].name}',
style: TextStyle(
fontWeight: FontWeight.bold,
height: _height,
fontSize: 18)),
new Text('${availableEvents[index].description}',
style: TextStyle(height: _height)),
new Text('${availableEvents[index].address}',
style: TextStyle(height: _height)),
new Text('${availableEvents[index].datetime}',
style: TextStyle(height: _height)),
//new Text('${availableEvents[index].managerId}', style: TextStyle(height: _height)),
new FlatButton(
onPressed: null,
// Simply call joinEvent for event 'availableEvents[index]'
color: Colors.redAccent,
textColor: Colors.white,
disabledColor: Colors.red,
disabledTextColor: Colors.white,
padding: EdgeInsets.all(8.0),
splashColor: Colors.redAccent,
child: Text('Join!'),
)
],
));
},
);
}));
Here is the fetchUserByID method:
Future<User> fetchUserbyId(String id) async {
final response =
await http.get('https://url-here.com' + id);
//print("response : " + response.body);
if (response.statusCode == 200) {
// If the call to the server was successful, parse the JSON.
return User.fromJson(json.decode(response.body));
} else {
// If that call was not successful, throw an error.
throw Exception('Failed to load post');
}
}

Answer 1

If what I'm understanding is you have two asynchronous calls, where the second one needs the results of the first call to execute. The best way to go around this is to create a helper method, i.e. getData(). In this method you make your call to events and then use that to fetchUserbyId. This would result in your FutureBuilder looking something like this:
FutureBuilder(
future: getData()
builder: ... // get the results the same why you got your results from events in the given example.
);
Then in you getData() method it would look something like this:
Future<User> getData() async {
var availableEvents= await events; // not sure what your events data/method is
return fetchUserbyId((availableEvents[index].managerId).toString());
}
I think I answered your question, but if I missed it please comment.
Note: On a completely unrelated topic, you don't need the new keyword in Flutter anymore to instantiate objects. Hope that speeds up your development process!