Flutter get mysql database value - flutter

Question

I'm trying to get value from mysql database into my flutter project(these using pagination). i'm add custom data and its work. but cant fetch my database value
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_datagrid/datagrid.dart';
import 'package:http/http.dart'as http;
class AllQuestion extends StatefulWidget {
String fldPaperTypeID;
AllQuestion({this.fldPaperTypeID});
#override
_AllQuestionState createState() => _AllQuestionState();
}
List<Question> _question;
List<Question> populateData;
QuestionDataSource _questionDataSource = QuestionDataSource();
List<Question> paginatedDataSource = [];
class _AllQuestionState extends State<AllQuestion> {
bool showLoadingIndicator = true;
Future<List> GetAllQuestion() async{
final response = await http.post('http://eduapp.studysmile.lk/getquestion',body: {"fldPaperTypeID":widget.fldPaperTypeID});
return json.decode(response.body);
}
#override
void initState() {
// TODO: implement initState
super.initState();
_question = populateData();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Question'),
),
body: LayoutBuilder(
builder: (context, constraints) {
return Row(children: [
Column(
children: [
SizedBox(
height: constraints.maxHeight - 60,
width: constraints.maxWidth,
child: buildStack(constraints)),
Container(
height: 60,
width: constraints.maxWidth,
child: SfDataPager(
rowsPerPage: 1,
direction: Axis.horizontal,
onPageNavigationStart: (int pageIndex) {
setState(() {
showLoadingIndicator = true;
});
},
delegate: _questionDataSource,
onPageNavigationEnd: (int pageIndex) {
setState(() {
showLoadingIndicator = false;
});
},
),
)
],
),
]);
},
),
);
}
Widget buildDataGrid(BoxConstraints constraint) {
return SfDataGrid(
source: _questionDataSource,
columnWidthMode: ColumnWidthMode.fill,
columns: <GridColumn>[
GridNumericColumn(mappingName: 'id', headerText: 'ID'),
GridTextColumn(mappingName: 'name', headerText: 'Name'),
GridNumericColumn(mappingName: 'salaryS', headerText: 'Salary'),
]);
}
Widget buildStack(BoxConstraints constraints) {
List<Widget> _getChildren() {
final List<Widget> stackChildren = [];
stackChildren.add(buildDataGrid(constraints));
if (showLoadingIndicator) {
stackChildren.add(Container(
color: Colors.black12,
width: constraints.maxWidth,
height: constraints.maxHeight,
child: Align(
alignment: Alignment.center,
child: CircularProgressIndicator(
strokeWidth: 3,
),
),
));
}
return stackChildren;
}
return Stack(
children: _getChildren(),
);
}
/* List<Question> populateData() {
return [
Question(10001, 'James', 20000),
Question(10002, 'Kathryn', 30000),
Question(10001, 'James', 20000),
Question(10002, 'Kathryn', 30000),
Question(10001, 'James', 20000),
Question(10002, 'Kathryn', 30000),
Question(10001, 'James', 20000),
Question(10002, 'Kathryn', 30000),
Question(10001, 'James', 20000),
Question(10002, 'Kathryn', 30000),
];
}*/
Future<List<Question>> populateData()async{
final response = await http.post('http://eduapp.studysmile.lk/getquestion',body:
{"fldPaperTypeID":widget.fldPaperTypeID});
List<Question> populateData = json.decode(response.body);
return populateData;
}
}
/*
class SendallQuestion extends StatelessWidget {
List list;
SendallQuestion({this.list});
#override
Widget build(BuildContext context) {
return ListView.builder(
itemCount: list == null?0:list.length,
itemBuilder: (ctx,i){
return Container(
alignment: Alignment.center,
margin: EdgeInsets.all(20),
child: FlatButton(
child: Align(
alignment: Alignment(0.2, 0.6),
child: Text(list[i]['fldQuestion'], style: TextStyle(fontSize: 20.0),)
),
color: Color(0xff7c4dff),
textColor: Colors.white,
onPressed: (){
},
),
);
}
);
}
}*/
class Question{
final int fldQuestionID;
final int fldPaperTypeID;
final String fldQuestion;
Question(this.fldPaperTypeID,this.fldQuestion,this.fldQuestionID);
}
class QuestionDataSource extends DataGridSource<Question> {
#override
List<Question> get dataSource => paginatedDataSource;
#override
Object getValue(Question question, String columnName) {
switch (columnName) {
case 'id':
return question.fldPaperTypeID;
break;
case 'name':
return question.fldQuestionID;
break;
case 'salaryS':
return question.fldQuestion;
break;
default:
return ' ';
break;
}
}
#override
int get rowCount => _question.length;
#override
Future<bool> handlePageChange(int oldPageIndex, int newPageIndex,
int startRowIndex, int rowsPerPage) async {
int endIndex = startRowIndex + rowsPerPage;
if (endIndex > _question.length) {
endIndex = _question.length - 1;
}
await Future.delayed(Duration(milliseconds: 2000));
paginatedDataSource = List.from(
_question.getRange(startRowIndex, endIndex).toList(growable: false));
notifyListeners();
return true;
}
}
this was my error message **lib/allquestionview.dart:42:17: Error: A value of type 'Future<List>' can't be assigned to a variable of type 'List'.
'Future' is from 'dart:async'.
'List' is from 'dart:core'.
'Question' is from 'package:studysmile/allquestionview.dart' ('lib/allquestionview.dart').
_question = populateData();
^**

Answer 1

in your case i guess this will do the trick :
List _question = List();
Future GetAllQuestion() async{
final response = await http.post('http://eduapp.studysmile.lk/getquestion',body: {"fldPaperTypeID":widget.fldPaperTypeID});
var data = json.decode(response.body);
setState(() {
_question= data;
});
}
void initState() {
// TODO: implement initState
super.initState();
this.GetAllQuestion();
}

Answer 2

Try this code. It works.
import 'package:http/http.dart' as http;
import 'package:json_helpers/json_helpers.dart';
Future main() async {
final list = await populateData();
print(list[0].fldQuestion);
}
Future<List<Question>> populateData() async {
final typeID = '1';
final response = await http.post(
Uri.parse('http://eduapp.studysmile.lk/getquestion'),
body: {'fldPaperTypeID': typeID});
if (response.statusCode == 200) {
return response.body.jsonList((e) => Question.fromJson(e));
} else {
throw 'Bad response';
}
}
class Question {
final String fldQuestionID;
final String fldPaperTypeID;
final String fldQuestion;
Question({this.fldPaperTypeID, this.fldQuestion, this.fldQuestionID});
factory Question.fromJson(Map<String, dynamic> json) {
return Question(
fldPaperTypeID: json['fldPaperTypeID'] as String,
fldQuestion: json['fldQuestion'] as String,
fldQuestionID: json['fldQuestionID'] as String);
}
}
Output:
1. දත්ත සැකසීමට පෙර වලංගුතාවය පරික්ෂා කිරීමේදී අනුගමනය කළ යුතු වඩාත් නිවැරදි අනුපිළිවෙල වන්නේ