How do I pass data from a stateful widget to state ensuring widget data is available? - flutter

Question

I'm passing data from a stateful widget, and I access it like in this example (widget.variable)
https://stackoverflow.com/a/50818870/806009
However, occasionally it throws an error (about 1 in 20) for a line in this comparison
════════ Exception caught by widgets library ═══════════════════════════════════════════════════════
The method '>' was called on null.
Receiver: null
Tried calling: >(10)
if (widget.x > 10){...}
It seems that widget.x is not known at this time. Should I use initState to ensure that value is "ready"?
Such as
#override
void initState() {
super.initState();
this.x = widget.x
}
Full Code
class PlayerSelection extends StatefulWidget {
final int teamId;
final int leagueId;
final League.League league;
final String className;
List<PlayerObj> playersListOfClass;
final int index;
final int remaining;
PlayerSelection({Key key, #required this.teamId, this.leagueId, this.league, this.className, this.playersListOfClass, this.index, this.remaining}) : super(key: key);
#override
_PlayerSelection createState() => _PlayerSelection();
}
class _PlayerSelection extends State<PlayerSelection> {
var playerWidgets = <Widget>[];
List<PlayerObj> selectedPlayers = [];
List<PlayerObj> playerList = [];
PlayerObj draftedPlayer;
List<PlayerClass> playerClassList = [];
bool _isFavorited = false;
Modal modal = new Modal();
int lineupWeek = 0;
int lineupSize = 0;
String intervalLabel = '';
bool _is_full = false;
bool _is_locked = false;
int remaining = 0;
var currentColor = Colors.black;
var rejectedPlayerId;
#override
void initState() {
super.initState();
}
#override
Widget build(BuildContext context) {
return new Scaffold(
resizeToAvoidBottomPadding: false,
appBar: globals.MyAppBar(
leading: IconButton(icon: Icon(Icons.close),
onPressed: (){
Navigator.pop(context, {'player': null,'index': this.widget.index});
}), // go to league route,),
title: Text(widget.className)
),
body: Container(
child: Column(children: [Expanded(child: ListView(children: _getLineup(this.widget.playersListOfClass))),]),
),
);
}
List<Widget>_getLineup(playerList) {
List<Widget> widgets = [];
var index = 0;
playerList.forEach((player) =>
widgets.add(
Padding(
padding: const EdgeInsets.symmetric(horizontal:16.0),
child: Container(
decoration: BoxDecoration(
color: Colors.white,
border: Border(
bottom: BorderSide(width: 1.0, color: Colors.grey.withOpacity(0.3)),
),
),
child: new ListTile(
leading: GestureDetector(
onTap: (){
if(!_is_full) {
Navigator.push(
context,
MaterialPageRoute(builder: (context) =>
Players.PlayerDetail(playerId: player.playerId,
leagueId: widget.leagueId,
playerName: player.playerName,
playerBio: player.playerBio)),
);
}
},
child: ClipOval(
child: _playerPicWidget(player)
),
),
title: GestureDetector(
onTap: (){
Navigator.push(
context,
MaterialPageRoute(builder: (context) =>
Players.PlayerDetail(playerId: player.playerId,
leagueId: widget.leagueId,
playerName: player.playerName,
playerBio: player.playerBio)),
);
},
child: _playerNameWidget(player)
),
trailing: _trailingWidget(player),
onTap: () => player.playerPrice <= widget.remaining ? Navigator.pop(context, {'player': player,'index': this.widget.index}) : null,
// return player back
),
),
)
)
);
return widgets;
}
Widget _playerNameWidget(player){
if(this._is_full && !this.selectedPlayers.contains(player)){ //show disabled selection
return Opacity(opacity:.25, child:Text("${player.playerName}"));
}
else {
if(this.widget.league.hasBudget){ // can afford player, not full
if(player.playerPrice <= widget.remaining || this.selectedPlayers.contains(player)){
return Text("${player.playerName}");
}
else { // can't afford player, not full
return Opacity(opacity:.25, child:Text("${player.playerName}"));
}
}
else { // slot still open
return Text("${player.playerName}");
}
}
}
Widget _playerPicWidget(player){
if(player == this.draftedPlayer){
return Opacity(opacity: .25, child: Image.network('${player.playerImageUrl}',
fit: BoxFit.scaleDown,
height: 45,
width: 45,
));
}
else {
if(player.playerPrice <= widget.remaining || this.selectedPlayers.contains(player)){
return Image.network('${player.playerImageUrl}',
fit: BoxFit.scaleDown,
height: 45,
width: 45,
);
}
}
}
Widget _trailingWidget(player){
List<Widget> tWidgets;
double playerOpacity = 1;
if(player.playerPrice > widget.remaining){
playerOpacity = .25;
}
tWidgets = [
Padding(padding: const EdgeInsets.symmetric(horizontal:10.0),
child: Opacity(opacity:playerOpacity, child:Text("\$${globals.commaFormat.format(player.playerPrice)}")),
), Opacity(opacity: playerOpacity, child: Icon(Icons.add))];
return Row(mainAxisSize: MainAxisSize.min, children: tWidgets);
}
}

Answer 1

The issue was a data issue unrelated to the passing of data.