我已将Excel文件上传到实时数据库。我是新手，觉得很方便。特别是在需要将数据卸载回以在Excel文件中进行处理的情况下。因此，很难找到有关如何在应用程序中自定义搜索栏的课程。请帮忙。如果您能告诉我在哪里可以学习使用Dart语言创建的应用程序的数据库，我也将很高兴。
class UserDashboard extends StatefulWidget {
@override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<UserDashboard> implements AddUserCallback {
TextEditingController editingController = TextEditingController();
bool _anchorToBottom = false;
FirebaseDatabaseUtil databaseUtil;
@override
void initState() {
super.initState();
databaseUtil = FirebaseDatabaseUtil();
databaseUtil.initState();
}
@override
void dispose() {
super.dispose();
databaseUtil.dispose();
}
@override
Widget build(BuildContext context) {
Widget _buildTitle(BuildContext context) {
return InkWell(
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 12.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'List of students',
style: TextStyle(
fontWeight: FontWeight.bold,
color: Colors.white,
),
),
],
),
),
);
}
List<Widget> _buildActions() {
return <Widget>[
new IconButton(
icon: const Icon(
Icons.group_add,
color: Colors.white,
),
onPressed: () => showEditWidget(null, false),
),
];
}
return new Scaffold(
appBar: AppBar(
title: _buildTitle(context),
actions: _buildActions(),
backgroundColor: Colors.deepPurple,
),
body: Container(
child: Column(children: <Widget>[
Expanded(
child: FirebaseAnimatedList(
key: ValueKey<bool>(_anchorToBottom),
query: databaseUtil.getUser(),
reverse: _anchorToBottom,
sort: _anchorToBottom
? (DataSnapshot a, DataSnapshot b) => b.key.compareTo(a.key)
: null,
itemBuilder: (BuildContext context, DataSnapshot snapshot,
Animation<double> animation, int index) {
return SizeTransition(
sizeFactor: animation,
child: showUser(snapshot),
);
},
),
),
]),
));
}
@override
void addUser(User user) {
setState(() {
databaseUtil.addUser(user);
});
}
@override
void update(User user) {
setState(() {
databaseUtil.updateUser(user);
});
}
Widget showUser(DataSnapshot res) {
User user = User.fromSnapshot(res);
var item = Card(
child: Container(
child: Center(
child: Row(
children: <Widget>[
CircleAvatar(
radius: 30.0,
child: Text(getShortName(user)),
backgroundColor: const Color(0xFF20283e),
),
Expanded(
child: Padding(
padding: EdgeInsets.all(10.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(
user.name,
// set some style to text
style: TextStyle(
fontSize: 20.0, color: Colors.deepPurple),
),
Text(
user.club,
// set some style to text
style: TextStyle(
fontSize: 20.0, color: Colors.lightBlueAccent),
),
],
),
),
),
Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
IconButton(
icon: const Icon(
Icons.edit,
color: Colors.deepPurple,
),
onPressed: () => showEditWidget(user, true),
),
IconButton(
icon: const Icon(Icons.delete_forever),
color: Colors.deepPurple,
onPressed: () => onDelete(user),
),
],
),
],
),
),
padding: const EdgeInsets.fromLTRB(10.0, 0.0, 0.0, 0.0)),
);
return item;
}
String getShortName(User user) {
String shortName = "";
if (!user.name.isNotEmpty) {
shortName = user.name.substring(0, 1);
}
return shortName;
}
showEditWidget(User user, bool isEdit) {
showDialog(
context: context,
builder: (BuildContext context) =>
AddUserDialog().buildAboutDialog(context, this, isEdit, user),
);
}
void onDelete(User user) async {
if (await _showConfirmationDialog(context)) {
databaseUtil.deleteUser(user);
}
}
Future<bool> _showConfirmationDialog(BuildContext context) async {
return showDialog(
context: context,
barrierDismissible: true,
builder: (context) => AlertDialog(
content: Text("Delete?"),
actions: <Widget>[
FlatButton(
textColor: Colors.red,
child: Text("Delete"),
onPressed: () => Navigator.pop(context, true),
),
FlatButton(
textColor: Colors.black,
child: Text("Cancel"),
onPressed: () => Navigator.pop(context, false),
),
],
));
}
}
这是我将数据加载和卸载到应用程序中的方式：
class FirebaseDatabaseUtil {
DatabaseReference _counterRef;
DatabaseReference _userRef;
StreamSubscription<Event> _counterSubscription;
StreamSubscription<Event> _messagesSubscription;
FirebaseDatabase database = FirebaseDatabase();
int _counter;
DatabaseError error;
static final FirebaseDatabaseUtil _instance =
new FirebaseDatabaseUtil.internal();
FirebaseDatabaseUtil.internal();
factory FirebaseDatabaseUtil() {
return _instance;
}
void initState() {
// Demonstrates configuring to the database using a file
_counterRef = FirebaseDatabase.instance.reference().child('counter');
// Demonstrates configuring the database directly
_userRef = database.reference().child('record');
database.reference().child('counter').once().then((DataSnapshot snapshot) {
print('Connected to second database and read ${snapshot.value}');
});
database.setPersistenceEnabled(true);
database.setPersistenceCacheSizeBytes(10000000);
_counterRef.keepSynced(true);
_counterSubscription = _counterRef.onValue.listen((Event event) {
error = null;
_counter = event.snapshot.value ?? 0;
}, onError: (Object o) {
error = o;
});
}
DatabaseError getError() {
return error;
}
int getCounter() {
return _counter;
}
DatabaseReference getUser() {
return _userRef;
}
addUser(User user) async {
final TransactionResult transactionResult =
await _counterRef.runTransaction((MutableData mutableData) async {
mutableData.value = (mutableData.value ?? 0) + 1;
return mutableData;
});
if (transactionResult.committed) {
_userRef.push().set(<String, String>{
"Name": "" + user.name,
"date": "" + user.date,
"email": "" + user.email,
"phone": "" + user.phone,
"Place": "" + user.place,
"Club": "" + user.club,
}).then((_) {
print('Transaction committed.');
});
} else {
print('Transaction not committed.');
if (transactionResult.error != null) {
print(transactionResult.error.message);
}
}
}
void deleteUser(User user) async {
await _userRef.child(user.id).remove().then((_) async{
await _counterRef.runTransaction((MutableData mutableData) async {
mutableData.value = (mutableData.value ?? 0) - 1;
return mutableData;
});
print('Transaction committed.');
});
}
void updateUser(User user) async {
await _userRef.child(user.id).update({
"Name": "" + user.name,
"date": "" + user.date,
"email": "" + user.email,
"phone": "" + user.phone,
"Place": "" + user.place,
"Club": "" + user.club,
}).then((_) {
print('Transaction committed.');
});
}
void dispose() {
_messagesSubscription.cancel();
_counterSubscription.cancel();
}
}
以下是RTDB的信息：
Datafetchfrom
counter: 2
record
0
Club:"Club1"
Name:"Name1"
Place:"City1"
date: "31737"
email:"sss@gmail.com"
phone:"98988"
2
Club:"Club2"
Name:"Name2"
Place:"City2"
date: "34334"
email:"ddd@gmail.com"
phone:"12333"