我的一个项目需要帮助。 我有一个带有三个标签的底部导航栏。在第二页中，我正在通过弹出窗口将数据添加到数据库，然后将其显示在列表中。 我能够添加和显示数据。但是我导航到另一个屏幕，然后返回数据不存在，不确定发生了什么？
还有另一件事navigator.pop无法关闭对话框。
//Database class
class DatabaseHelper{
static final DatabaseHelper _instance = new DatabaseHelper.internal();
factory DatabaseHelper() => _instance;
static Database _db;
Future<Database> get db async{
if(_db != null){
return _db;
}
_db = await initDb();
return _db;
}
DatabaseHelper.internal();
initDb() async{
io.Directory documentDirectry = await getApplicationDocumentsDirectory();
String path = join(documentDirectry.path, "DataBaseV.db");
var ourDb = await openDatabase(path, version: 1, onCreate: _onCreate);
return ourDb;
}
void _onCreate(Database db, int version) async{
await db.execute("CREATE TABLE ControllerTable(ControllerId INTEGER PRIMARY KEY, ControllerName TEXT, ControllerNumber TEXT, ControllerDateCreated TEXT)");
print("Controller table is created");
}
//insertion
Future<int> saveController(Controller controllerTable) async{
var dbClient = await db;
int res = await dbClient.insert("ControllerTable", controllerTable.toMap());
return res;
}
//Get from database
Future<List> getItems() async{
var dbClient = await db;
var result = await dbClient.rawQuery("SELECT * FROM ControllerTable");
return result.toList();
}
Future<Controller> getItem(int id) async{
var dbClient = await db;
var result = await dbClient.rawQuery("SELECT * FROM ControllerTable WHERE ControllerId = $id");
if(result.length == 0) return null;
return new Controller.fromMap(result.first);
}
Future close() async{
var dbClient = await db;
return dbClient.close();
}
}
//Model Class
class Controller extends StatelessWidget {
String _ControllerName;
String _ControllerNumber;
String _ControllerDateCreated;
int _ControllerId;
Controller(this._ControllerName, this._ControllerNumber, this._ControllerDateCreated);
Controller.map(dynamic obj){
this._ControllerName = obj['ControllerName'];
this._ControllerNumber = obj['ControllerNumber'];
this._ControllerDateCreated = obj['ControllerDateCreated'];
this._ControllerId = obj['ControllerId'];
}
String get ControllerName => _ControllerName;
String get ControllerNumber => _ControllerNumber;
String get ControllerDateCreated => _ControllerDateCreated;
int get ControllerId => _ControllerId;
Map<String, dynamic> toMap(){
var map = new Map<String, dynamic>();
map["ControllerName"] = _ControllerName;
map["ControllerNumber"] = _ControllerNumber;
map["ControllerDateCreated"] = _ControllerDateCreated;
if(_ControllerId != null){
map["ControllerId"] = _ControllerId;
}
return map;
}
Controller.fromMap(Map<String, dynamic> map){
this._ControllerName = map["ControllerName"];
this._ControllerNumber = map["ControllerNumber"];
this._ControllerDateCreated = map["ControllerDateCreated"];
this._ControllerId = map["ControllerId"];
}
@override
Widget build(BuildContext context) {
return new
ListTile(
leading: new CircleAvatar(
backgroundColor: Colors.cyan,
child: new Text(
_ControllerName[0],
//"V",
style: new TextStyle(color: Colors.black),
),
),
title: new Text(_ControllerName, style: TextStyle(
color: Colors.white, fontWeight: FontWeight.bold
),),
subtitle: new Text(_ControllerNumber, style: TextStyle(
color: Colors.white, fontStyle: FontStyle.italic
),),
);
}
}
//Second Screen
class ContainerHome extends StatefulWidget {
@override
_ContainerHomeState createState() => _ContainerHomeState();
}
class _ContainerHomeState extends State<ContainerHome> {
var db = DatabaseHelper();
final _textEditingControllerName = new TextEditingController();
final _textEditingControllerNumber = new TextEditingController();
final _formKey = new GlobalKey<FormState>();
final List<Controller> _itemList = <Controller>[];
//List widgets = [];
@override
void initState() {
super.initState();
_controllerList();
}
// Save the data to database
void _handelSubmitted(String controllerName, String controllerNumber) async{
Controller controller = new Controller(controllerName, controllerNumber, DateTime.now().toIso8601String());
int savedItemId = await db.saveController(controller);
Controller addedItem = await db.getItem(savedItemId);
setState(() {
_itemList.insert(0, addedItem);
});
print("Item saved id $savedItemId");
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: ListView.builder(
reverse: false,
itemCount: _itemList.length,
itemBuilder: (BuildContext context, int index) {
return Card(
color: Colors.black.withOpacity(0.6),
child: new ListTile(
title: _itemList[index],
onLongPress: () => {},
//_updateItem(context, _itemList[index], index),
trailing: new Listener(
key: new Key(_itemList[index].ControllerName),
child: new Icon(
Icons.delete,
color: Colors.redAccent,
),
onPointerDown: (pointerEvent) => {},
//_deleteToDo(_itemList[index].id, index),
),
),
); //getRow(index);
}),
floatingActionButton: new FloatingActionButton(
onPressed: () {
_showFormDialog();
/*showDialog(
context: context,
builder: (_) => new SimpleDialog(
title: new Text("Add Controler"),
children: <Widget>[
Padding(
padding:
const EdgeInsets.symmetric(horizontal: 14.0),
child: Column(
children: <Widget>[
TextFormField(
controller: _textEditingControllerName,
validator: (val) => val.length == 0 ? "Enter Controller name": null,
//onSaved: (val) => this._ControllerName = val,
decoration: InputDecoration(
labelText: "Name",
),
),
TextFormField(
controller: _textEditingControllerNumber,
validator: (val) => val.length == 0 ? "Enter Controller number": null,
//onSaved: (val) => _ControllerNumber = val,
decoration: InputDecoration(
labelText: "Number",
),
keyboardType: TextInputType.number,
),
Row(
children: <Widget>[
Padding(
padding:
const EdgeInsets.only(left: 18.0),
child: Center(
child: RawMaterialButton(
onPressed: () {
_handelSubmitted(_textEditingControllerName.text, _textEditingControllerNumber.text);
_textEditingControllerName.clear();
_textEditingControllerNumber.clear();
},
fillColor: Colors.indigo,
splashColor: Colors.white,
child: Padding(
padding: EdgeInsets.symmetric(
horizontal: 6.0),
child: Text(
"SUBMIT",
style: TextStyle(
color: Colors.white),
),
),
shape: const StadiumBorder(),
),
),
),
SizedBox(
width: 22.0,
),
RawMaterialButton(
onPressed: () => Navigator.pop(context),
fillColor: Colors.deepOrange,
splashColor: Colors.white,
child: Padding(
padding: EdgeInsets.symmetric(
horizontal: 6.0),
child: Text(
"CANCEL",
style:
TextStyle(color: Colors.white),
),
),
shape: const StadiumBorder(),
),
],
)
],
))
],
));*/
},
tooltip: "Add Controler",
child: Icon(Icons.add))
);
}
void _showFormDialog() {
var alert = new AlertDialog(
title: Text("Add new Controller"),
content: Row(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
new Expanded(
child:
Form(
key: _formKey,
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
new TextFormField(
keyboardType: TextInputType.text,
controller: _textEditingControllerName,
validator: (value) {
if (value.isEmpty) {
return "Please enter your task";
}
},
autofocus: true,
decoration: new InputDecoration(
labelText: "Controller Name",
border: OutlineInputBorder(
borderRadius: BorderRadius.all(
const Radius.circular(0.0),
)),),
),
SizedBox.fromSize(
size: Size(0.0, 10.0),
),
new TextFormField(
//keyboardType: TextInputType.number,
controller: _textEditingControllerNumber,
validator: (value) {
if (value.isEmpty) {
return "Please enter your task";
}
},
autofocus: true,
decoration: new InputDecoration(
labelText: "Controller Number",
border: OutlineInputBorder(
borderRadius: BorderRadius.all(
const Radius.circular(0.0),
)),),
),
],
),
),
)
],
),
actions: <Widget>[
new OutlineButton(
onPressed: () {
_handelSubmitted(_textEditingControllerName.text, _textEditingControllerNumber.text);
_textEditingControllerName.clear();
_textEditingControllerNumber.clear();
},
borderSide: BorderSide(color: Colors.green),
child: Text("Save")),
new OutlineButton(
onPressed: () {
Navigator.pop(context);
},
borderSide: BorderSide(color: Colors.red),
child: Text("Cancel"))
],
);
showDialog(
context: context,
builder: (_) {
return alert;
});
}
// Retrive the data from database
_controllerList() async{
List items = await db.getItems();
items.forEach((item){
Controller controller = Controller.fromMap(item);
print("DB Items ${controller.ControllerName}");
print("DB Items ${controller.ControllerNumber}");
print("DB Items ${controller.ControllerId}");
});
}
}