Roberto Hermosilla F's questions

I need help with a pad that doesn't seem to be firing the fetch method I'm calling an API with.

The error I am getting is:

══╡ EXCEPTION CAUGHT BY PROVIDER ╞═══════════════════════════════
The following _CastError was thrown:
type 'Null' is not a subtype of type 'HomeBloc' in type cast

I am attaching code for the pad, class methods, main and widgets.

part 'home_event.dart';
part 'home_state.dart';

class HomeBloc extends Bloc<HomeEvent, HomeState> {
  final PlayerService _playerService;

  HomeBloc(this._playerService) : super(HomeLoadingState()) {
    on<LoadApiEvent>((event, emit) async {
      final player = await _playerService.fetchHomeData();
      emit(HomeLoadedState(player.playerId, player.playerName,
          player.playerPoints, player.playerEmail, player.playerAlbums));
    });
  }
}

part of 'home_bloc.dart';

abstract class HomeEvent extends Equatable {
  const HomeEvent();
}
class LoadApiEvent extends HomeEvent {
  @override
  List<Object?> get props => [];
}


part of 'home_bloc.dart';

abstract class HomeState extends Equatable {
  const HomeState();
}

class HomeLoadingState extends HomeState {
  @override
  List<Object> get props => [];
}

class HomeLoadedState extends HomeState {
  final int playerId;
  final String playerName;
  final String playerPoints;
  final String playerEmail;
  final List<PlayerAlbum> playerAlbums;

  const HomeLoadedState(this.playerId, this.playerName, this.playerPoints,
      this.playerEmail, this.playerAlbums);

  @override
  List<Object> get props =>
      [playerId, playerName, playerPoints, playerEmail, playerAlbums];
}

Attached main code and home widget, where the provider is used:

void main() {
  runApp(const MyApp());
}


    return MaterialApp(
        home: MultiRepositoryProvider(
      providers: [
        RepositoryProvider(
          create: (context) => PlayerService(),
        ),
      ],
      child: HomePageView(),
    ));

This is the home page widget that draws the content of the pad:

Widget build(BuildContext context) {
    return BlocProvider(
      create: (context) => HomeBloc(
        RepositoryProvider.of<PlayerService>(context),
      )..add(LoadApiEvent()),
      child: Scaffold(
        backgroundColor: Colors.blue.shade800,
        appBar: const CustomAppBar(title: "LaminApp"),
        bottomNavigationBar: CircularBottomNavigation(
          tabItems,
          selectedCallback: (int? selectedPos) {
            print("clicked on $selectedPos");
          },
          selectedPos: selectedPos,
          barBackgroundColor: Colors.white,
        ),
        body: SingleChildScrollView(
          child: Column(
            children: [
              const SizedBox(
                height: 30,
              ),
              BlocBuilder<HomeBloc, HomeState>(
                builder: (context, state) {
                  if (state is HomeLoadedState) {
                    return Text(
                      state.playerName,
                      style: CustomTextStyle.cardItemTextStyle,
                    );
                  } else {
                    return Container();
                  }
                },
              ),

I want to be able to have the value of a variable that I receive as a parameter from another screen through the class and insert the value of the variable in the elements of an array: import 'package:flutter/material.dart'; import 'package:carousel_slider/carousel_slider.dart';

class FotosPage extends StatefulWidget {
    final String id; //Este es el valor que recibo desde screen anterior
    FotosPage(this.id,{Key key}): super(key: key);


    @override
    FotosPageState createState() => FotosPageState();
}

class FotosPageState extends State<FotosPage> {
     CarouselSlider carouselSlider;
     int _current = 0;
     String _num;
     //Aqui trato de usar la variable _num y me arroja error: only static members can be accessed in initializers
     List imgList = [
    'https://xxxxxxxxxx.com/read/${_num}/1.jpg',
        'https://xxxxxxxxxx.com/read/${_num}/2.jpg',
    'https://xxxxxxxxxx.com/read/${_num}/3.jpg',

    ];

    @override
    initState() {
        _num = widget.id; //Paso el valor del parámetro recibido a la variable
        super.initState();
    }
}

I need to pass data from a page class to a widget on the same page:

class PrePerfil extends StatefulWidget {
  final String id_persona;
  PrePerfil(this.id_persona, {Key key}): super(key: key);

  @override
  _PrePerfilState createState() => _PrePerfilState();
}

I need to pass the value of person_id to the widget of another class called PageOne on the same page.

class PageOneState extends State<PageOne> {
  @override
  Widget build(BuildContext context) {
    return ListView.builder(
        itemCount: widget.dataList.length,
        itemBuilder: (context, index) {
          return ExpansionTile(
            key: PageStorageKey('${widget.dataList[index].id}'),
            //title: Text(widget.dataList[index].title),
            title: Text(id_persona), // Aqui está el error

In the last line (title) I need to use the person_id, but I can't add it.

Please your support, thank you very much!

I add all the page code

import 'package:flutter/material.dart';
import 'package:curved_navigation_bar/curved_navigation_bar.dart';


class PrePerfil extends StatefulWidget {
  final String id_persona;
  PrePerfil(this.id_persona, {Key key}): super(key: key);

  @override
  _PrePerfilState createState() => _PrePerfilState();
}

class _PrePerfilState extends State<PrePerfil> {
  final Key keyOne = PageStorageKey('pageOne');
  final Key keyTwo = PageStorageKey('pageTwo');


  int currentTab = 0;

  PageOne one;
  PageTwo two;
  List<Widget> pages;
  Widget currentPage;

  List<Data> dataList;
  final PageStorageBucket bucket = PageStorageBucket();

  @override
  void initState() {
    one = PageOne(
      key: keyOne,
      dataList: dataList,
    );
    two = PageTwo(
      key: keyTwo,
    );

    pages = [one, two];

    currentPage = one;

    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Persistance Example"),
      ),
      body: PageStorage(
        child: currentPage,
        bucket: bucket,
      ),

      bottomNavigationBar: CurvedNavigationBar(
        onTap: (int index) {
          setState(() {
            currentTab = index;
            currentPage = pages[index];
          });
        },
        items: <Widget>[
          Icon(Icons.account_circle,  color: Colors.white,size: 30),
          Icon(Icons.comment, color: Colors.white,size: 30),
          //Icon(Icons.business_center, color: Colors.white,size: 30),
        ],
        color: Colors.orangeAccent,
        backgroundColor: Colors.white,
      ),
    );
  }
}

class PageOne extends StatefulWidget {
  final List<Data> dataList;
  final String id_persona;
  PageOne({
    Key key,
    this.dataList, this.id_persona
  }) : super(key: key);

  @override
  PageOneState createState() => PageOneState();
}

class PageOneState extends State<PageOne> {
  @override
  Widget build(BuildContext context) {
    return ListView.builder(
        itemCount: widget.dataList.length,
        itemBuilder: (context, index) {
          return ExpansionTile(
            key: PageStorageKey('${widget.dataList[index].id}'),
            title: Text(widget.id_persona),
            children: <Widget>[
              Container(
                color: index % 2 == 0 ? Colors.orange : Colors.limeAccent,
                height: 100.0,
              ),
            ],
          );
        });
  }
}

class PageTwo extends StatefulWidget {
  PageTwo({Key key}) : super(key: key);

  @override
  PageTwoState createState() => PageTwoState();
}

class PageTwoState extends State<PageTwo> {
  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemExtent: 250.0,
      itemBuilder: (context, index) => Container(
        padding: EdgeInsets.all(10.0),
        child: Material(
          elevation: 4.0,
          borderRadius: BorderRadius.circular(5.0),
          color: index % 2 == 0 ? Colors.cyan : Colors.deepOrange,
          child: Center(
            child: Text(index.toString()),
          ),
        ),
      ),
    );
  }
}

class Data {
  final int id;
  bool expanded;
  final String title;
  Data(this.id, this.expanded, this.title);
}

I would like to change the size of this widget (page), thank you very much!!!

 Widget _mainContainer() {
 return new Container(
    child: new ListView(
      children: <Widget>[
        new Center(
          child: new Column(
            children: <Widget>[
            _formContainer(),
            ],
          ),
        ),
      ],
    ));
 }

It is a page in which I must implement many things, but ideally it should have a smaller size.

This is the main widget:

block quote

  Widget build(BuildContext context) {
    return new Scaffold(
    key: globalKey,
    backgroundColor: Colors.white,
    body: new Stack(
      children: <Widget>[_mainContainer(), progressDialogRegion],
    ));

}

I need to insert a textformfield at the bottom of my page with a button on the right. On this page and inside the build widget, I have a listview with a fixed size and I want a text to be entered at the end.

@override
Widget build(BuildContext context) {
return new Scaffold(
    appBar: new AppBar(
      title: new Text("Mensajes de trabajo"),
      backgroundColor: Colors.deepOrange,
    ),
    body: Container(
      height: 450,
      child: FutureBuilder(
        future: _capturaComuna(),
        builder: (BuildContext context, AsyncSnapshot snapshot){
          if (snapshot.data == null){
            return Container(
              child: Center(
                child: Text("Cargando...")
              )
            );
          } else {
            return ListView.builder(
              itemCount: snapshot.data.length,
              itemBuilder: (BuildContext context, int index) {
                return Card(
                  child: ListTile(
                    leading: CircleAvatar(
                      backgroundImage: NetworkImage(snapshot.data[index].imagen_mensaje),
                    ),
                    title: new Text(snapshot.data[index].nombre_persona + '   ' + snapshot.data[index].fecha_mensaje),
                    subtitle: Text(snapshot.data[index].texto_mensaje),
                  )
                );
              },
            );
          }
        }
      )
    )
  );
}

My problem is:

1. I fill a DropDownList with records obtained from an API
2. Then I select one of the items and this event fills a second DropDownList, which, like the first one, receives data from an API
3. When I click on the first DropDownList again I get the error:

Code of the first DropDownList

 Widget _regionesContainer() {
    return new Container(
      child: new DropdownButton<String>(
        items: dataRegion.map((item) {
          return new DropdownMenuItem<String>(
            value: item['ID_REGION'].toString(),
            child: new Text(item['NOMBRE_REGION'],
            style: new TextStyle(fontSize: 13.0)
          ),
          );
        }).toList(),
        hint: Text("Seleccione región"),
        onChanged: (String newValReg) {
          setState(() {
            _mySelectionReg = newValReg;
            capturaComuna(newValReg);
            Fluttertoast.showToast(msg: _mySelectionReg,
              fontSize: 18.0,
            );
          });
        },
        value: _mySelectionReg,
      ),
      margin: EdgeInsets.only(bottom: 40.0)
    );
  }

This is the code for the second DropDownList

    Widget _comunasContainer() {
    return new Container(
        child: new DropdownButton<String>(
          items: dataComuna.map((item) {
            return new DropdownMenuItem<String>(
              value: item['ID_COMUNA'].toString(),
              child: new Text(item['NOMBRE_COMUNA'],
                  style: new TextStyle(fontSize: 13.0)),
            );
          }).toList(),
          hint: Text("Seleccione comuna"),
          onChanged: (newValCom) {
            _mySelectionCom = newValCom;
            setState(() {
            });
          },
          value: _mySelectionCom,
        ),
        margin: EdgeInsets.only(bottom: 45.0)
    );
  }

This is the code for the future methods:

String _mySelectionReg;
  String _mySelectionCom;

  String urlRegion = "http://www.aquimaestros.cl/am/Region/Read.php";

  List dataRegion = List(); //Lista de regiones
  List dataComuna = List(); //Lista de comunas

  Future<String> getSWData() async {
    var res = await http
        .get(Uri.encodeFull(urlRegion), headers: {"Accept": "application/json"});
    var resBody = json.decode(res.body);
    setState(() {
      dataRegion = resBody;
    });
    print(resBody);
    return "Sucess";
  }

  Future<String> capturaComuna(String _id) async {
    String urlComuna = "http://www.aquimaestros.cl/am/Comuna/ReadxRegion.php?id_region=${_id}";
    var res = await http
        .get(Uri.encodeFull(urlComuna), headers: {"Accept": "application/json"});
    var resBody = json.decode(res.body);
    setState(() {
      dataComuna = resBody;
    });
    print(resBody);
    return "Sucess";
  }

The error occurs when clicking a second time on the DropDownList of the _regionesContainer widget, this is the error: