仅在热重载或刷新后才显示数据 [英] Data is showing only after I hot reload or refresh in flutter

问题描述

在我的数据库中，我有一个用户名表，其中存储了用户名和一些标记.当用户转到特定页面时，我想在表中查看该数据.因此，当我第一次进入该页面时，数据(用户名和标记)不会显示.但是，如果我热装或使用按钮刷新，则数据将正确显示.我的问题是，如何在不进行热重装或不使用刷新按钮的情况下做到这一点.这是我的代码:

In my database I have a user table where username, some marks are stored. I want to view that data in a table when user go to a particular page. So, when I go to that page at first the data(username and marks) doesn't show. But if I hot reload or use a button to refresh then the data shows properly. My question is how can I do that without hot reload or using a refresh button. Here is my code:

import 'package:flutter/material.dart';
import 'package:flutter_app/database/db_helper.dart';
import 'package:flutter_app/database/user.dart';

class ViewResult extends StatefulWidget {
 @override
 _ViewResult createState() => _ViewResult();
}

GlobalKey<ScaffoldState> scaffoldKey = new GlobalKey();

class _ViewResult extends State<ViewResult> {
 String tempEmail;
 bool check = true;

 var dbHelper;
 var data = List<User>();

 @override
 void initState() {
   setState(() {
     dbHelper = DBHelper();
     resultData();
   });
   super.initState();
 }

 void resultData() {
     dbHelper.getUser().then((users) {
       for (User temp in users) {
         if (temp.type == "student") data.add(temp);
       }
     });
 }

 @override
 Widget build(BuildContext context) {
   return Scaffold(
     appBar: AppBar(
       centerTitle: true,
       title: Text("Result"),
     ),
     body: DataTable(
       columnSpacing: 22,
       columns: [
         DataColumn(label: Text("Username")),
         DataColumn(label: Text("Beginner")),
         DataColumn(label: Text("Intermediate")),
         DataColumn(label: Text("Advanced")),
       ],
       rows: data
           .map((user) => DataRow(cells: [
                 DataCell(Text(user.email)),
                 DataCell(Text(user.beginnerMark.toString())),
                 DataCell(Text(user.intermediateMark.toString())),
                 DataCell(Text(user.advancedMark.toString())),
               ]))
           .toList(),
     ),
     backgroundColor: Color.fromRGBO(130, 178, 220, 1),
   );
 }
}

推荐答案

TLDR:如果在 then()内部调用 setState()否，它将在一切完成之前执行，并且完全没有效果.

TLDR: Call setState() from inside then() if not, it will be executed before everything completes and have no effect at all.

getUser().then((response) {
   //Your stuff

   setState(() {}); //refresh
  });

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