【发布时间】：2018-04-18 18:58:43
【问题描述】：
我需要使用来自数据库的数据创建 DialogItem 小部件。我尝试使用for(){}，但它不起作用。
你能帮我解决这个问题吗？
我把用过的代码和有效的证据都放了，只是不把DialogItem的动态列表和数据库的数据一起用。
要运行下面的代码，您需要将sqflite 和path_provider 依赖项插入pubspec.yaml，因此：
dependencies:
sqflite: any
path_provider: any
flutter:
sdk: flutter
DatabaseClient 类将创建包含 3 条记录的数据库。
在 gif 中只有 foo1 出现，正确的是出现来自数据库的列表的所有值：
[{name: foo1, color: 0}, {name: foo2, color: 1}, {name: foo3, color: 2}]
import 'package:flutter/material.dart';
import 'dart:async';
import 'dart:io';
import 'package:path/path.dart';
import 'package:sqflite/sqflite.dart';
import 'package:path_provider/path_provider.dart';
void main() {
runApp(new MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
home: new MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
DatabaseClient _db = new DatabaseClient();
int number;
List listCategory;
List colors = [
const Color(0xFFFFA500),
const Color(0xFF279605),
const Color(0xFF005959)
];
createdb() async {
await _db.create().then(
(data){
_db.countCategory().then((list){
this.number = list[0][0]['COUNT(*)']; //3
this.listCategory = list[1];
//[{name: foo1, color: 0}, {name: foo2, color: 1}, {name: foo3, color: 2}]
});
}
);
}
@override
void initState() {
super.initState();
createdb();
}
void showCategoryDialog<T>({ BuildContext context, Widget child }) {
showDialog<T>(
context: context,
child: child,
)
.then<Null>((T value) {
if (value != null) {
setState(() { print(value); });
}
});
}
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(),
body: new Center(
child: new RaisedButton(
onPressed: (){
showCategoryDialog<String>(
context: context,
child: new SimpleDialog(
title: const Text('Categories'),
children: <Widget>[
//for(var i = 0; i < this.number; i++) {
new DialogItem(
icon: Icons.brightness_1,
color: this.colors[
this.listCategory[0]['color']
//the zero should be dynamic going from 0 to 2 with the for(){}
//but o for(){} dont work
],
text: this.listCategory[0]['name'],
onPressed: () {
Navigator.pop(context, this.listCategory[0]['name']);
}
),
//}
]
)
);
},
child: new Text("ListButton"),
)
),
);
}
}
//Creating Database with some data and two queries
class DatabaseClient {
Database db;
Future create() async {
Directory path = await getApplicationDocumentsDirectory();
String dbPath = join(path.path, "database.db");
db = await openDatabase(dbPath, version: 1, onCreate: this._create);
}
Future _create(Database db, int version) async {
await db.execute("""
CREATE TABLE category (
id INTEGER PRIMARY KEY,
name TEXT NOT NULL,
color INTEGER NOT NULL
)""");
await db.rawInsert("INSERT INTO category (name, color) VALUES ('foo1', 0)");
await db.rawInsert("INSERT INTO category (name, color) VALUES ('foo2', 1)");
await db.rawInsert("INSERT INTO category (name, color) VALUES ('foo3', 2)");
}
Future countCategory() async {
Directory path = await getApplicationDocumentsDirectory();
String dbPath = join(path.path, "database.db");
Database db = await openDatabase(dbPath);
var count = await db.rawQuery("SELECT COUNT(*) FROM category");
List list = await db.rawQuery('SELECT name, color FROM category');
await db.close();
return [count, list];
}
}
//Class of Dialog Item
class DialogItem extends StatelessWidget {
DialogItem({
Key key,
this.icon,
this.size,
this.color,
this.text,
this.onPressed }) : super(key: key);
final IconData icon;
double size = 36.0;
final Color color;
final String text;
final VoidCallback onPressed;
@override
Widget build(BuildContext context) {
return new SimpleDialogOption(
onPressed: onPressed,
child: new Container(
child: new Row(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
new Container(
child: new Container(
margin: size == 16.0 ? new EdgeInsets.only(left: 7.0) : null,
child: new Icon(icon, size: size, color: color),
)
),
new Padding(
padding: size == 16.0 ?
const EdgeInsets.only(left: 17.0) :
const EdgeInsets.only(left: 16.0),
child: new Text(text),
),
],
),
)
);
}
}
【问题讨论】：
标签： database sqlite dart flutter