I have a flutter stateful page. Here it is:
class TestPage extends StatefulWidget {
static const String id = 'TestPage';
final String testString;
TestPage(this.testString);
#override
_TestPageState createState() => _TestPageState();
}
class _TestPageState extends State<TestPage> {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(child: Text('Hello ${widget.testString}'))
);
}
}
The page has a constructor that takes in a string as a default value.
final String testString;
From another page, I make a call to that page. I want to open it and give it or pass to it a String value:
Navigator.pushNamed(context, TestPage(myString));
However, it is telling me:
that the argument type 'TestPage' cannot be assigned to the parameter type String.
What am I doing wrong? Is this not the correct way to instantiate this class and make it appear?
Thank you
Try with this,
Navigator.push( context, MaterialPageRoute( builder: (context) => TestPage(testString: 'Hello',), ));
Related
I'm having trouble with accessing the value of a parameter from a constructor in my code. I access to this page from another one where I get the value of the parameter:
final route = MaterialPageRoute(
builder: (context) => AnadirJugadores(idPagina: respuesta['id'],));
Navigator.push(context, route);
This is the code of AnadirJugadores:
class AnadirJugadores extends StatefulWidget {
final String idPagina;
AnadirJugadores({required this.idPagina });
String cogerID() {
return this.idPagina;
}
#override
State<AnadirJugadores> createState() => _AnadirJugadoresState();
}
class _AnadirJugadoresState extends State<AnadirJugadores> {
#override
Widget build(BuildContext context) {
.... more code
ElevatedButton(
child: Text(idPartida), // this is the line of the error
onPressed: () {
final data = ClipboardData(text: '25342756374');
Clipboard.setData(data);
},
),
I'm trying to access the value of idPagina. How could I do that?
Thanks in advance.
When using stateful widgets you need to use widget to access the parameters.
child: Text(widget.idPartida),
In StatefulWidget your constructor exists in upper class (it's not in State class), so to access data in this constructor in your state class you should do this:
ElevatedButton(child: Text(widget.idPartida), ...),
I tried to put the route to Another Class on the Same Page and wrote this code as mentioned in the flutter Doc, but I get this:
error: The return type CategoryState isn't a Widget, as required
by the closure's context.
Page code:
Navigation code:
According to the documentation: the builder function of the MaterialPageRoute class should return a widget. Both StatelessWidget and StatefulWidget extend the Widget class and thus can be used here.
But in your case the CategoryState class does not extend any of them, and it's the reason you are having that error.
You need to use the Category class instead.
It should then look like:
PAGE :
class Category extends StatefulWidget {
#override
_CategoryState createState() => _CategoryState();
}
class _CategoryState extends State<Category> {
#override
Widget build(BuildContext context) {
return Column(
children: [
Container(child: Text("Music")),
Container(child: Text("Projects")),
Container(child: Text("Essay")),
],
);
}
}
NAVIGATION
Navigator.push(
context,
MaterialPageRoute(builder: (context) => Category())
);
Furthermore, I would advise you to add a suffix to this class name (e.g. CategoryScreen) in order to avoid name conflicts in case you have another class (e.g. a model) with the same name.
class CategoryState is not a widget it's just a Dart class you want to navigate to Category()
I'm making my first flutter app.
it asks for some information then when you click a button it shows the information you entered on another page, I wanted to ask. How do I get a variable from another class?
so I can use the information entered on another page
It seems like you want to pass some data while navigating to another page. If I'm not wrong You should define a variable in the destination like this:
class NewPage extends StatefulWidget {
final int someInt;
NewPage({Key key, this.someInt}) : super(key: key);
#override
_NewPageState createState() => _NewPageState();
}
class _NewPageState extends State<NewPage> {
#override
Widget build(BuildContext context) {
return Container(
child: Container(child: Text("${widget.someInt}"),),
);
}
}
In the above code I passed someInt to NewPage class.
In the first page you should navigate like this:
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => NewPage(someInt: 293,),
));
put above code in the onPressed and pass the data with constructor.
this is my code, i dont know how to pass this listOfTiles to my StatefulWidget, can u help me and describe how it works?
body: new ListView.builder(
itemBuilder: (BuildContext context, int index) {
return new StuffInTilesState(listOfTiles[index]);//i want to pass this
},
itemCount: listOfTiles.length,
),
),
);
}
}
class StuffInTiles extends StatefulWidget{
#override
StuffInTilesState createState() => StuffInTilesState();//i know i need to change this, but i dont know how
}
class StuffInTilesState extends State<StuffInTiles> {
final MyTile myTile;
StuffInTilesState(this.myTile);//this is constructor, shuld this also be changed?
final _controller = TextEditingController();
String name = "";
If u want to see my working code: https://pastebin.pl/view/c4dbc2af If u want to see my not working code: https://pastebin.pl/view/83f9cad0 (https://codeshare.io/GLLm66)
You need to use the widget class constructor and not the state class.
You can access the values in the state class with widget.YouProperty
class StuffInTiles extends StatefulWidget {
final MyTile myTile;
const StuffInTiles(this.myTile);
#override
_StuffInTilesState createState() => _StuffInTilesState();
}
class _StuffInTilesState extends State<StuffInTiles> {
#override
Widget build(BuildContext context) {
return Container(child:
Text(widget.myTile),);
}
}
I'm trying to access the information I've passed over from a previous class before the build method begins. But it's saying only static members can be accessed in initializers. I don't really want to use the static property, partially because I wouldn't know how to use it, but also because I think it seems unnecessary. In previous pages I've been able to access the data but only after the build method, does anyone know how I can access it before? Thanks all
class FirstPage extends StatefulWidget {
#override
_FirstPageState createState() => _FirstPageState();
}
class _FirstPageState extends State<FirstPage> {
List<MyProvider> myList;
#override
Widget build(BuildContext context) {
return Scaffold(
body: ListView.builder(
itemCount: myList.length,
itemBuilder: (context, index) {
String imgPath = myList[index].image;
String myTextPath = myList[index].name;
String locationNamePath = myList[index].location;
double distancePath = myList[index].distance;
String myName = '${myTextPath} ''${locationNamePath}';
return MyCard(
locationText: locationNamePath,
myText: myTextPath,
assetImage: Image.network(imgPath),
function: (){
Provider.of<Data>(context, listen: false).addLogo(Image.network(imgPath));
Navigator.push(context, MaterialPageRoute(builder: (context) => SecondPage(myName: myName,)));
},
);
}),
);
}
}
My next page accesses the data using a key but it seems not to be able to use it before the build method, and that's what I need to get around!
class SecondPage extends StatefulWidget {
final String myName;
const SecondPage({Key key, this.myName})
: super(key: key);
#override
_SecondPageState createState() => _SecondPageState();
}
class _SecondPageState extends State<SecondPage> with TickerProviderStateMixin {
final CollectionReference myItemsReference = Firestore.instance.collection('${widget.myName}');
// This is where the error is
#override
Widget build(BuildContext context) {
return Scaffold();
}
}
Use the initState method for anything related to initialization of State. See this for more on initState.
Example:
CollectionReference myItemsReference;
#override
void initState() {
myItemsReference = Firestore.instance.collection('${widget.myName}');
}