将文档中的值从数据库保存到 initState 值的颤振问题
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【中文标题】将文档中的值从数据库保存到 initState 值的颤振问题【英文标题】：Flutter problem with saving the value from document from database to a initState value 【发布时间】：2021-05-06 22:33:28 【问题描述】：我在从数据库文档中获取值到 initState 方法中调用的变量时遇到问题。当我这样做时，空值存在问题，我认为 Firebase 的 get() 方法获取值太晚了（当我重新加载场景时会发生这种情况）。
bool _dark;
bool options;
MainModel model;
final MyUser myUser;
final UserSettings userSettings;
_SettingsOnePageState(this.userSettings, this.myUser);
final user = FirebaseAuth.instance.currentUser;
@override
void initState()
super.initState();
// _dark = false;
FirebaseFirestore.instance
.collection("settings")
.doc(user.uid)
.get()
.then((value)
print(value.data()['darkMode']);
_dark = value.data()['darkMode'];
);
options = false;
Brightness _getBrightness()
return _dark ? Brightness.dark : Brightness.light;
@override
Widget build(BuildContext context)
return Theme(
// return StreamProvider<QuerySnapshot>.value(
isMaterialAppTheme: true,
data: ThemeData(
brightness: _getBrightness(),
),
// value: SettingsUser().settings,
child: StreamBuilder<UserSettings>(
//setting the stream for settings from database
stream: DatabaseUser(userId: user.uid).userData,
builder: (context, snapshot)
if (snapshot.hasData)
//data for user from database
UserSettings userSettings = snapshot.data;
// _dark = userSettings.darkMode;
// print("dark mode " + userSettings.darkMode.toString());
return Form(
key: _formKey,
child: Scaffold(
backgroundColor: _dark ? null : Colors.grey.shade200,
appBar: AppBar(
//elevation: 10,
brightness: _getBrightness(),
iconTheme: IconThemeData(
color: _dark ? Colors.white : Colors.black),
backgroundColor: Colors.transparent,
title: Text(
'Change theme',
style: TextStyle(
color: _dark ? Colors.white : Colors.black),
textAlign: TextAlign.center,
),
actions: <Widget>[
IconButton(
icon: Icon(Icons.auto_awesome),
onPressed: ()
setState(()
_dark = !_dark;
);
,
)
],
),
body: Stack(fit: StackFit.expand, children: <Widget>[
SingleChildScrollView(
//padding: const EdgeInsets.all(16.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Stack(
children: <Widget>[
Align(
alignment: Alignment.center,
child: Text(
userSettings.nick,
textScaleFactor: 4,
style: TextStyle(
color: _dark
? Colors.white
: Colors.purple[500],
//fontWeight: FontWeight.w500,
),
)),
const SizedBox(height: 50.0),
],
),
Stack(
children: <Widget>[
Align(
alignment: Alignment.center,
child: Container(
// width: 200,
// height: 200,
child: CircleAvatar(
radius: 100.0,
backgroundImage:
//NetworkImage(user.photoURL),
NetworkImage(
userSettings.pictureUrl),
),
),
),
],
),
//const SizedBox(height: 20.0),
if (options == true) ...[
//SettingsEdit(),
//NickChange(),
ImageInput(),
],
const SizedBox(height: 10.0),
Card(
elevation: 4.0,
margin: const EdgeInsets.fromLTRB(
32.0, 8.0, 32.0, 16.0),
shape: RoundedRectangleBorder(
borderRadius:
BorderRadius.circular(10.0)),
child: Column(
children: <Widget>[
ListTile(
leading: Icon(
Icons.account_box,
color: Colors.purple,
),
title: Text("Change Nickname"),
trailing:
Icon(Icons.keyboard_arrow_right),
onTap: ()
//open change nick
//changeNick();
,
),
_buildDivider(),
ListTile(
leading: Icon(
Icons.add_a_photo,
color: Colors.purple,
),
title: Text("Change Photo"),
trailing:
Icon(Icons.keyboard_arrow_right),
onTap: ()
//open change photo
//changePhoto();
,
),
_buildDivider(),
ListTile(
leading: Icon(
Icons.lock_rounded,
color: Colors.purple,
),
title: Text("Change Password"),
trailing:
Icon(Icons.keyboard_arrow_right),
onTap: ()
//open change password
//changePassword();
,
),
_buildDivider(),
ListTile(
leading: Icon(
Icons.location_on,
color: Colors.purple,
),
title: Text("Change Your Location"),
trailing:
Icon(Icons.keyboard_arrow_right),
onTap: ()
//open change location
,
),
],
),
),
const SizedBox(height: 20.0),
]))
])));
return Scaffold();
));
debug console settings where I use theme now
你知道如何在 initState 中避免这个 null 吗？我正在尝试更改应用程序的主题，并从用户注册时创建的 Firebase 文档中获取该主题。比我将在用户设置中更改它并且还想在整个应用程序中使用它（这个主题）。 感谢您的帮助
【问题讨论】：
【参考方案1】：InitState 不是异步的（意味着执行不会等待您的 firebase 调用完成）。这意味着您的视图将在您分配 _dark 值之前呈现。
如果您想等到该调用完成，请使用名为 FutureBuilder 的名称。
【讨论】：
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