我正在尝试使用 Flutter 和 Firebase 构建我的第一个移动应用程序。 当我尝试显示和存储照片时,出现以下问题:
error: The argument type 'Future' can't be assigned to the parameter type 'File'. (argument_type_not_assignable at [whereassistant] lib/main.dart:85)
我可能应该做一些 Actor ,但我不明白如何正确地做。
这是我的 future 文件声明:
Future<File> _imageFile;
我正在拍摄一张显示在屏幕上的照片:
setState(() {
_imageFile = ImagePicker.pickImage(source: source);
});
但我在尝试将照片发送到 Firebase 时遇到错误:
final StorageUploadTask uploadTask = ref.put(_imageFile);
final Uri downloadUrl = (await uploadTask.future).downloadUrl;
这是我使用的基于代码示例的类:
class _MyHomePageState extends State<MyHomePage> {
Future<File> _imageFile;
void _onImageButtonPressed(ImageSource source) async {
GoogleSignIn _googleSignIn = new GoogleSignIn();
var account = await _googleSignIn.signIn();
final GoogleSignInAuthentication googleAuth = await account.authentication;
final FirebaseUser user = await _auth.signInWithGoogle(
accessToken: googleAuth.accessToken,
idToken: googleAuth.idToken,
);
assert(user.email != null);
assert(user.displayName != null);
assert(!user.isAnonymous);
assert(await user.getIdToken() != null);
final FirebaseUser currentUser = await _auth.currentUser();
assert(user.uid == currentUser.uid);
setState(() {
_imageFile = ImagePicker.pickImage(source: source);
});
var random = new Random().nextInt(10000);
var ref = FirebaseStorage.instance.ref().child('image_$random.jpg');
final StorageUploadTask uploadTask = ref.put(_imageFile);
final Uri downloadUrl = (await uploadTask.future).downloadUrl;
}
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: const Text('Where Assistant'),
),
body: new Center(
child: new FutureBuilder<File>(
future: _imageFile,
builder: (BuildContext context, AsyncSnapshot<File> snapshot) {
debugPrint('test recup image');
print(snapshot);
if (snapshot.connectionState == ConnectionState.done &&
snapshot.data != null) {
return new Image.file(snapshot.data);
} else if (snapshot.error != null) {
return const Text('Error picking image.');
} else {
return const Text('No image so far.');
}
},
),
),
floatingActionButton: new Column(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
new FloatingActionButton(
onPressed: () => _onImageButtonPressed(ImageSource.gallery),
tooltip: 'Pick an image from gallery',
child: new Icon(Icons.photo_library),
),
new Padding(
padding: const EdgeInsets.only(top: 16.0),
child: new FloatingActionButton(
onPressed: () => _onImageButtonPressed(ImageSource.camera),
tooltip: 'Take a Photo',
child: new Icon(Icons.camera_alt),
),
),
],
),
);
}
}
最佳答案
ref.put
要求 File
作为参数。您传递的是 Future<File>
.
您需要等待 future 的结果才能调用电话。
您可以将代码更改为
final StorageUploadTask uploadTask = ref.put(await _imageFile);
final Uri downloadUrl = (await uploadTask.future).downloadUrl;
或更改_imageFile
至File
而不是 Future<File>
关于firebase - flutter/Dart 错误 : The argument type 'Future<File>' can't be assigned to the parameter type 'File' ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/49854024/