Flutter Dropdown with sqllite-CodePudding

Good noon every one i want to ask on how to put a dropdown onchanged i am using sqllite for my database.

error encounter [{ "resource": "/c:/Users/VIMS-SERVER/Documents/Flutter Projects/apps/lib/widget/note_form_widget.dart", "owner": "generated_diagnostic_collection_name#0", "code": { "value": "undefined_method", "target": { "$mid": 1, "external": "https://dart.dev/diagnostics/undefined_method", "path": "/diagnostics/undefined_method", "scheme": "https", "authority": "dart.dev" } }, "severity": 8, "message": "The method 'setState' isn't defined for the type 'NoteFormWidget'.\nTry correcting the name to the name of an existing method, or defining a method named 'setState'.", "source": "dart", "startLineNumber": 228, "startColumn": 9, "endLineNumber": 228, "endColumn": 17 }]

[{ "resource": "/c:/Users/VIMS-SERVER/Documents/Flutter Projects/apps/lib/widget/note_form_widget.dart", "owner": "generated_diagnostic_collection_name#0", "code": { "value": "undefined_identifier", "target": { "$mid": 1, "external": "https://dart.dev/diagnostics/undefined_identifier", "path": "/diagnostics/undefined_identifier", "scheme": "https", "authority": "dart.dev" } }, "severity": 8, "message": "Undefined name 'dropdownValue'.\nTry correcting the name to one that is defined, or defining the name.", "source": "dart", "startLineNumber": 229, "startColumn": 11, "endLineNumber": 229, "endColumn": 24 }]

[{ "resource": "/c:/Users/VIMS-SERVER/Documents/Flutter Projects/apps/lib/widget/note_form_widget.dart", "owner": "generated_diagnostic_collection_name#0", "code": { "value": "undefined_identifier", "target": { "$mid": 1, "external": "https://dart.dev/diagnostics/undefined_identifier", "path": "/diagnostics/undefined_identifier", "scheme": "https", "authority": "dart.dev" } }, "severity": 8, "message": "Undefined name 'newValue'.\nTry correcting the name to one that is defined, or defining the name.", "source": "dart", "startLineNumber": 229, "startColumn": 27, "endLineNumber": 229, "endColumn": 35 }]

edit_note_page.dart

 Widget build(BuildContext context) => Scaffold(
        appBar: AppBar(
          actions: [buildButton()],
        ),
        body: Form(
          key: _formKey,
          child: NoteFormWidget(
          
            category: category,
            
            
            
            onChangedCategory: (category) => setState(() => this.category = category),
          
          ),
        ),
      );

note_form_widget.dart

Widget buildCategory() => DropdownButton(
      icon: const Icon(Icons.keyboard_arrow_down),
      items: <String>['A1', 'A2', 'A3', 'A4','A5','C1']
          .map<DropdownMenuItem<String>>((String value) {
        return DropdownMenuItem<String>(
          value: category,
          child: Text(value),
        );
      }).toList(), onChanged: (String? value) 
      { 
        setState(() {
          dropdownValue = newValue!;//im getting an error on this part 
        });
      },

error encounter 
The method 'setState' isn't defined for the type 'NoteFormWidget'.
Try correcting the name to the name of an existing method, or defining a method named 'setState'.

[{
    "resource": "/c:/Users/VIMS-SERVER/Documents/Flutter Projects/apps/lib/widget/note_form_widget.dart",
    "owner": "_generated_diagnostic_collection_name_#0",
    "code": {
        "value": "undefined_identifier",
        "target": {
            "$mid": 1,
            "external": "https://dart.dev/diagnostics/undefined_identifier",
            "path": "/diagnostics/undefined_identifier",
            "scheme": "https",
            "authority": "dart.dev"
        }
    },
    "severity": 8,
    "message": "Undefined name 'dropdownValue'.\nTry correcting the name to one that is defined, or defining the name.",
    "source": "dart",
    "startLineNumber": 229,
    "startColumn": 11,
    "endLineNumber": 229,
    "endColumn": 24
}]

[{
    "resource": "/c:/Users/VIMS-SERVER/Documents/Flutter Projects/apps/lib/widget/note_form_widget.dart",
    "owner": "_generated_diagnostic_collection_name_#0",
    "code": {
        "value": "undefined_identifier",
        "target": {
            "$mid": 1,
            "external": "https://dart.dev/diagnostics/undefined_identifier",
            "path": "/diagnostics/undefined_identifier",
            "scheme": "https",
            "authority": "dart.dev"
        }
    },
    "message": "Undefined name 'newValue'.\nTry correcting the name to one that is defined, or defining the name.",
    
}]

CodePudding user response：

The setState method doesn't work on StatelessWidget because StatelessWidget doesn't have a state. Only StatefulWidget has a state, and therefore only it has a setState. So you most turn your StatelessWidget to StatefulWidget.

CodePudding user response：

I think your note_widget is stateless so you change to the stateful widget. you cant use a set state callback on the stateless widget.Dartpad live check here.you can use another state management tool(Provider ,cubit,riverport,bloc) to update your value

   DropdownButton(
        icon: const Icon(Icons.keyboard_arrow_down),
        items: <String>['A1', 'A2', 'A3', 'A4', 'A5', 'C1']
            .map<DropdownMenuItem<String>>((String value) {
          return DropdownMenuItem<String>(
            value: value,
            child: Text(value),
          );
        }).toList(),
        value: dropdownvalu,
        onChanged: (values) {
          setState(() {
            dropdownvalu = values.toString();
          });
        },
      )

Widget

class _ParentState extends State<Parent> {
  Widget build(context) {
    return Scaffold(
      appBar: AppBar(
        actions: <Widget>[
          IconButton(
            onPressed: () {
              setState(() {
                counter  ;
              });
            },
            icon: const Icon(Icons.add),
          ),
        ],
      ),
      body: Column(
        children: [
          DropdownButton(
            icon: const Icon(Icons.keyboard_arrow_down),
            items: <String>['A1', 'A2', 'A3', 'A4', 'A5', 'C1']
                .map<DropdownMenuItem<String>>((String value) {
              return DropdownMenuItem<String>(
                value: value,
                child: Text(value),
              );
            }).toList(),
            value: dropdownvalu,
            onChanged: (values) {
              setState(() {
                dropdownvalu = values.toString();
              });
            },
          ),
          Center(
              child: Text(
            "$dropdownvalu",
            style: TextStyle(fontSize: 30),
          )),
        ],
      ),
    );
  }
}

SampleCode

import 'package:flutter/material.dart';
//import 'package:pucon/home.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Parent(),
    );
  }
}

class Parent extends StatefulWidget {
  @override
  State<Parent> createState() => _ParentState();
}

String dropdownvalu = "A1";

class _ParentState extends State<Parent> {
  Widget build(context) {
    return Scaffold(
      appBar: AppBar(
        actions: <Widget>[
          IconButton(
            onPressed: () {
              setState(() {
                counter  ;
              });
            },
            icon: const Icon(Icons.add),
          ),
        ],
      ),
      body: Column(
        children: [
          DropdownButton(
            icon: const Icon(Icons.keyboard_arrow_down),
            items: <String>['A1', 'A2', 'A3', 'A4', 'A5', 'C1']
                .map<DropdownMenuItem<String>>((String value) {
              return DropdownMenuItem<String>(
                value: value,
                child: Text(value),
              );
            }).toList(),
            value: dropdownvalu,
            onChanged: (values) {
              setState(() {
                dropdownvalu = values.toString();
              });
            },
          ),
          Center(
              child: Text(
            "$dropdownvalu",
            style: TextStyle(fontSize: 30),
          )),
        ],
      ),
    );
  }
}

int counter = 0;

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

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

class _ChildState extends State<Child> {
  @override
  Widget build(BuildContext context) {
    return Center(
        child: Text(
      "$dropdownvalu",
      style: TextStyle(fontSize: 30),
    ));
  } //to be incremented when the parent's button is clicked on.

}

CodePudding user response：

// dbHelper

Future<List> getEmployeeData() async {
    try {
      final dbClient = await db;
      var l = await dbClient!.transaction(
        (txn) async => txn.rawQuery("SELECT * FROM ${DbConstants.tblGloEmployeeMaster} where is_active = 1"),
      );
      return l;
    } catch (e) {
      return [];
    }
  }

// getx 
  // login controller
    // init 

  final employeeModelList = List<EmployeeModel>.empty(growable: true).obs;

// create method

 void _getEmployees() async {
    List list = await _dbHelper.getEmployeeData();
    employeeModelList.value = [];
    employeeModelList.value = list.map((employeeModel) => EmployeeModel.fromJson(employeeModel)).toList();

  }

// create model

class EmployeeModel {
  EmployeeModel({
    required this.employeeId,
    required this.employeeNm,
  });


  late final int employeeId; 
  late final String employeeNm;

  EmployeeModel.fromJson(Map<String, dynamic> json) {
    employeeId = json['employee_id'];
    employeeNm = json['employee_nm'];
  }

  Map<String, dynamic> toJson() {
    final _data = <String, dynamic>{};
    _data['employee_id'] = employeeId;
    _data['employee_nm'] = employeeNm;
    return _data;
  }
}

// stateless widget


// call

Container(
      child: _searchEmployee(context),
       ),


// method

 Widget _searchEmployee(BuildContext context) {
    return Obx(
      () => CustomSearchableDropDown(
        items: _loginController.employeeModelList,
        label: Strings.selectEmployee,
        labelStyle: Theme.of(context).textTheme.bodyText1!.merge(TextStyles.defaultRegular),
        dropdownLabelStyle: Theme.of(context).textTheme.bodyText1!.merge(TextStyles.defaultRegular),
        dropDownMenuItems: _loginController.employeeModelList.map((item) {
          return "${item.employeeId} - ${item.employeeNm}"; // ui view
        }).toList(),
        suffixIcon:
            Icon(Icons.arrow_drop_down, size: Sizes.s16, color: Get.isDarkMode ? AppColors.white : AppColors.black),
        decoration: BoxDecoration(border: Border(bottom: BorderSide(color: AppColors.fontGray))),
        onChanged: (value) {
          if (value != null) {
            EmployeeModel employeeModel = value;
            _loginController.employeeId.value = int.parse(employeeModel.employeeId);
            _loginController.employeeName.value = employeeModel.employeeNm;
          }
        },
      ),
    );
  }