I want to get the data from the constructor and passes it to a variable.
I dont want it to be listed...
Class:
class ListaProjetos extends StatefulWidget {
ListaProjetos({Key key, this.title, this.jsonData}) : super(key: key);
static const String routeName = "/ListaProjetos";
final String title;
final List jsonData;
#override
_ListaProjetosState createState() => _ListaProjetosState();
}
I want to:
class _ListaProjetosState extends State<ListaProjetos> {
var message = widget.jsonData;
print(message);
//HERE I WANT TO PRINT ALL JSON DATA
}
Inside the class you need create a method and place the variables initialization, for example:
#override
void initState() {
var message = widget.jsonData;
print(message);
}
Or you can declare the var outside of the method to use it in others methods.
var message;
#override
void initState() {
message = widget.jsonData;
print(message);
}
Related
Here is the child class that receives from its parent the index data that identifies the box to modify
class InformationPatient extends StatefulWidget {
final Patients patients;
final int index;
const InformationPatient(this.patients, this.index, {Key? key})
: super(key: key);
#override
State<InformationPatient> createState() => _InformationPatientState();
}
class _InformationPatientState extends State<InformationPatient> {
final int indexitem = 0;
late Box<Patients> boxPatient;
#override
void initState() {
super.initState();
boxPatient = Hive.box('Patient');
}
void _addNote(String newtitle, String newnote, String newconclusion) {
final newNOTE = Patients(
listOfNotes: [
ListNote(title: newtitle, note: newnote, conclusion: newconclusion)
],
);
boxPatient.put(indexitem, newNOTE);
Navigator.of(context).pop();
}
This way works but I don't have the index of the parent, I give it to him
final int indexitem = 0; <--- Works perfectly with my function patientbox.put() it receives the index
boxPatient.put(indexitem, newNOTE);
I would like to give indexbox the value of index but I don't know how to do it or if there is another way
final int indexitem = ??? <---- add the value of index
boxPatient.put(indexitem, newNOTE);
obviously I can't use index directly in the function boxPatient.put()
Thank you very much for your help
To read variables from the widget inside the state, you can simply refer to widget.<variable>. So in your example
boxPatient.put(widget.index, newNOTE);
I'm trying to store the result of a method in a string , but i get errors
String _location(dynamic media){
return media['url'];
}
String myUrl = _location(media);
full class
class Home extends StatefulWidget {
const Home({Key? key}) : super(key: key);
#override
State<Home> createState() => _HomeState();
}
class _HomeState extends State<Home> {
Future<List<dynamic>> fetchMedia() async {
final result = await http
.get(Uri.parse('https://iptv-
org.github.io/api/streams.json'));
return json.decode(result.body);
}
String _location(dynamic media) {
return media['url'];
}
String myUrl = _location(media);
...
}
The error says The instance member '_location' can't be accessed in an initializer. Try replacing the reference to the instance member with a different expression
How can i do this ??
The problem is that I did not find that you have defined and inited the variable called media. You had defined a private function called _location it was fine, but when you were using this function you are passing an undefined and un-inited variable called media.
try
late String myUrl;
void _location(dynamic media){
myUrl = media['url'];
}
_location(media);
class Notice extends StatefulWidget {
final String s_id;
const Notice({Key key, this.s_id}) : super(key: key);
#override
_NoticeState createState() => _NoticeState();
}
class _NoticeState extends State<Notice> {
TextEditingController _titleController = new TextEditingController();
var api =
Uri.parse('https://www.a2rstore.in/api/school/v1/noticeApi.php?id=${widget.s_id}');
You can't call the "widget" without the context.
The proper way to do it is by first defining your variable:
class _NoticeState extends State<Notice> {
TextEditingController _titleController = new TextEditingController();
var api;
...
}
And then assigning to it the value either in the build or initState method:
#override
initState(){
api = Uri.parse('https://www.a2rstore.in/api/school/v1/noticeApi.php?id=${widget.s_id}');
}
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 want to make a data list page. It needs a reference based on user id passed by argument. However, the argument can't be accessed because it is not static.
I tried to pass reference itself by argument. But it also falls into the same problem.
class DataViewHome extends StatefulWidget{
final String userId;
DataViewHome({this.userId});
#override
State<StatefulWidget> createState() => DataViewHomeState();
}
class DataViewHomeState extends State<DataViewHome>{
final dataReference = FirebaseDatabase.instance.reference().child("users").child(widget.userId);
List<String> dataList = new List();
StreamSubscription<Event> _onDataAddedSubscription;
DataViewHomeState(){
_onDataAddedSubscription = dataReference.onChildAdded.listen(_onDataAdded);
}
_onDataAdded(Event event){
setState(() {
dataList.add(event.snapshot.value);
});
}
}