I want to load comments in my post here. For that I need to send post id to my HTTP get request. post id I sent from another page. but I want to assign that String id; value to final response = await http.get("http://$ip:$apiPort/solutions/$id"); here id in Flutter.
How can I do that?
to clear what I want
my code is
class Solutions extends StatefulWidget {
String id ;
final bool isEditMode;
Solutions({
this.id,
this.isEditMode,
});
#override
_SolutionsState createState() => _SolutionsState();
}
class _SolutionsState extends State<Solutions> {
List data;
var ip = Configuration.yourIp;
var apiPort = Configuration.yourApiPort;
Future<List> getData() async {
final response = await http.get("http://$ip:$apiPort/solutions/$id");
return json.decode(response.body);
}
#override
void initState() {
super.initState();
this.getData();
}
#override
Widget build(BuildContext context) {
return Scaffold(
Future<List> getData() async {
final response = await http.get("http://$ip:$apiPort/solutions/${widget.id}");
return json.decode(response.body);
}
This should to the trick.
From the State class (_SolutionState in your case), you can access the widget (Solution in your case) members by finding them in widget.
BONUS
Your id should be final, since StatefulWidget is marked as an immutable class, which means its members should all be final. You have surely a warning about this from your IDE.
Related
I am having big time trouble with getting the data from my method getAllPlayerData() outside the .then((Value).
The "bad print" in my code shows up before my "good print". I want to be able to use my variable "TheStats" in my code with all the data inside of it and not a "null" value or "instance of Future<Dynamic"
import 'package:cleanmaybe/Controllers/players_controller.dart';
import 'package:flutter/material.dart';
class PlayerStatView extends StatefulWidget {
const PlayerStatView({Key? key}) : super(key: key);
#override
State<PlayerStatView> createState() => _PlayerStatViewState();
}
class _PlayerStatViewState extends State<PlayerStatView> {
var theStats;
#override
void initState() {
getAllPlayerData().then((value) {
theStats = value;
print("Good print $theStats");
});
super.initState();
}
#override
Widget build(BuildContext context) {
print("bad print $theStats");
return Container();
}
}
This is my "getAllPlayerData()"
getAllPlayerData() async{
SharedPreferences sp = await _pref;
int? id = sp.getInt('idPlayer');
final statAccess = DatabaseModel();
var lookForData = await statAccess.getPlayerData(id);
return lookForData;
}
And if you need it, this is my getPlayerData(id) method that fetches all the data from my database:
Future getPlayerData(idPlayer) async {
var dbCoach = await db;
var dataPlayer = dbCoach!.rawQuery("SELECT * FROM players WHERE"
" idPlayer = '$idPlayer'");
return dataPlayer;
}
Your "bad print" will practically always run before "Good print" as long as getAllPlayerData() take any time at all to process with this construct.
There are several ways to handle this, but a suggestion is to use the FutureBuilder widget for it (as #pskink just wrote as a comment :)) Check the offical documentation.
I hope you could help me!
Error saying 'tables' has not been initiliazed. But when I set tables = [] instead of
widget.data.then((result) {tables = result.tables;})
it works. I think the problem comes from my app state data which is a Future.
My simplified code:
class NavBar extends StatefulWidget {
final Future<Metadata> data;
const NavBar({Key? key, required this.data}) : super(key: key);
#override
State<NavBar> createState() => _NavBarState();
}
class _NavBarState extends State<NavBar> {
late List<MyTable> tables;
#override
void initState() {
widget.data.then((result) {
tables = result.tables;
});
super.initState();
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: buildPages(page.p)
)
);
}
Widget buildPages(index){
switch (index) {
case 0:
return ShowTablesNew(tables: tables);
case 1:
return const Details();
case 2:
return const ShowTables();
default:
return const ShowTables();
}
}
}
Future doesn't contain any data. It's an asynchronous computation that will provide data "later". The initialization error happens because the variable 'tables' is marked as late init but is accessed before the future is completed, when in fact it's not initialized yet.
Check this codelab for async programming with dart.
For your code you can use async/await in the initState method doing something like this
String user = '';
#override
void initState() {
asyncInitState();
super.initState();
}
void asyncInitState() async {
final result = await fetchUser();
setState(() {
user = result;
});
}
but since you're using a list of custom objects the most straightforward way is probably to use a FutureBuilder widget
I try to pass data from page one to page two data is pass OK but I have one problem now.
this is my code:
class SecondScreen extends StatefulWidget {
final int itemHolder ;
SecondScreen({Key key, #required this.itemHolder}) : super(key: key);
#override
State<StatefulWidget> createState() {
return new mainState();
}
}
class mainState extends State <SecondScreen> {
bool value = false ;
MyPreferences _myPreferences = MyPreferences();
#override
void initState() {
// TODO: implement initState
super.initState();
initial();
}
void initial() async {
setState(() {
});
}
final String apiURL = 'http://xxxxxxxxx/getFlowersList.php';
Future<List<Flowerdata>> fetchFlowers() async {
var response = await http.get(apiURL);
if (response.statusCode == 200) {
final items = json.decode(response.body).cast<Map<String, dynamic>>();
List<Flowerdata> listOfFruits = items.map<Flowerdata>((json) {
return Flowerdata.fromJson(json);
}).toList();
return listOfFruits;
}
else {
throw Exception('Failed to load data from Server.');
}
}
I try to use var (itemHolder ) in the link like that:
final String apiURL = 'http://xxxxxxx/getFlowersList.php?id=' +itemHolder;
but I get error:
Undefined name 'itemHolder'. Try correcting the name to one that is defined, or defining the name.
I can access to itemHolder. So how can I access to it?
try this:
...
String apiURL;
#override
void initState() {
super.initState();
apiURL = 'http://xxxxxxx/getFlowersList.php?id=' +widget.itemHolder.toString();
}
...
To use the variables declared in the SecondScreen you have to access it with the prefix 'widget' and the dot operator, not directly. Here is the code:
final String apiURL = 'http://xxxxxxx/getFlowersList.php?id=' + widget.itemHolder;
And when you make the variable final, you have to initialize it while declaration or through constructor else delete keyword final:
I am so confused about state management.
Below is I pass down data through widgets.
List<AppUser> userList = List<AppUser>();
List<List<MessageType>> messageLists = new List<List<MessageType>>();
#override
void initState() {
super.initState();
loadUsers();
}
Future<void> loadUsers() async {
userList.clear();
userList.addAll(await AppUser.getRelatedUsers(customer.customerID));
defaultUser = await AppUser.getDefaultUser(customer.customerID);
if (defaultUser != null && !await defaultUser.hideUserTab()) {
userList.add(defaultUser);
}
await loadMessageList();
}
Then I pass the userList and messageList to another stateful widget. But what if I want to have those data through the whole app using inherited widget or provider or bloc.
MessageTypePage(
messageTypeList: messageLists[tabIndex],
currentUser: userList[tabIndex],
);
How can I possible to get the data from db and store them in inherited widget then using those data? I am so confused.
class StateContainer extends StatefulWidget {
final Widget child;
final List<AppUser> userList;
final List<Message> messageList;
StateContainer({#required this.child, this.userList, this.messageList});
static StateContainerState of(BuildContext context) {
return context.dependOnInheritedWidgetOfExactType<_InheritedStateContainer>().data;
}
#override
StateContainerState createState() => new StateContainerState();
}
class StateContainerState extends State<StateContainer> {
List<AppUser> userList = List<AppUser>();
List<List<MessageType>> messageLists = new List<List<MessageType>>();
#override
Widget build(BuildContext context) {
return _InheritedStateContainer(
data: this,
child: widget.child,
);
}
}
class _InheritedStateContainer extends InheritedWidget {
final StateContainerState data;
_InheritedStateContainer({Key key, #required this.data, #required Widget child}) : super(key: key, child: child);
#override
bool updateShouldNotify(_InheritedStateContainer oldWidget) {
return true;
}
}
In my opinion, the best approach is to use Provider or Bloc. There is a flutter codelab that uses Provider to do something very similar to what you are doing. It stores a list of items (in your case that would be Users) that can be used throughout the app. It also shows you how to manipulate the list in various ways.
The codelab is here. I think it would help you out.
Am trying to connect on a SignalR server with flutter, and I tried to use Provider to access the data which comes to another Widget, but am receiving a null value. This is the SignalR library for flutter am using.
Below is my Class which extends a ChangeNotifier :
class BreakingNewsSignalRClient with ChangeNotifier {
String _breakingNews;
Future<void> getBreakingNews() async {
final hubConnection = HubConnectionBuilder()
.withUrl('https://services.xxxx.com/breakingNews')
.build();
await hubConnection.start();
hubConnection.on("UpdateBreakingNews", (data){
_breakingNews = data.toString();
print(data.toString());
notifyListeners();
});
hubConnection.onclose((error) => print("Connection Closed"));
}
String get breakingNewsFunction => _breakingNews;
}
class BreakingNewsModel {
final String News;
BreakingNewsModel(this.News);
}
As you can see the code above, am having a getter String get breakingNewsFunction => _breakingNews;, this is called in another Stateful Widget to populate some data from the SignalR server, but it returns null in the other widget, however, when you try to print data here in the getBreakingNews method the data is shown.
Below is another Widget class which receives the data :
class BreakingNews extends StatefulWidget {
const BreakingNews({Key key, #required this.article, #required this.index})
: super(key: key);
final Article article;
final int index;
#override
_BreakingNewsState createState() => _BreakingNewsState();
}
class _BreakingNewsState extends State<BreakingNews> {
settings() async{
var breakingNewsInfo =
Provider.of<BreakingNewsSignalRClient>(context, listen: false);
await breakingNewsInfo.getBreakingNews();
print('lets see -- ${breakingNewsInfo.breakingNewsFunction}');
}
#override
void initState() {
// TODO: implement initState
settings();
super.initState();
}
}
So when you look at this line print('lets see -- ${breakingNewsInfo.breakingNewsFunction}');, it prints null, am still wondering what am doing wrong here.
Kindly need some help.
Did you try data[0]?
Can you write it?
_breakingNews = data[0].toString();
instead of
_breakingNews = data.toString();
This is pretty simple. Your Future<void> getBreakingNews() async returns void and therefore null. Just adjust the return type to whatever you need.
Edit:
Actually, the problem is you are not calling your getter here.
await breakingNewsInfo.getBreakingNews();
So either return your result from the function, or call the getter. Either should work.