The image Url gets null

Question

Future uploadImageToFirebase() async{
FirebaseStorage _storage = FirebaseStorage.instance;
StorageReference reference = _storage.ref().child("Products/${Path.basename(_image.path)}");
StorageUploadTask uploadTask = reference.putFile(_image);
await uploadTask.onComplete;
reference.getDownloadURL().then((fileURL) {
setState(() {
url = fileURL.toString();
});
});
print(url);
}

如果第一次调用函数，URL将返回null，但如果我再次调用它，它将返回正确的URL。请帮我找出代码出了什么问题。如果我点击RaiseButton一次，它就会返回null，但如果我第二次点击，它会返回正确的URL。

W/StorageUtil( 9524): no auth token for request
W/NetworkRequest( 9524): no auth token for request
I/System.out( 9524): (HTTPLog)-Static: isSBSettingEnabled false
I/System.out( 9524): (HTTPLog)-Static: isSBSettingEnabled false
W/StorageUtil( 9524): no auth token for request
W/NetworkRequest( 9524): no auth token for request
I/System.out( 9524): (HTTPLog)-Static: isSBSettingEnabled false
I/System.out( 9524): (HTTPLog)-Static: isSBSettingEnabled false
W/StorageUtil( 9524): no auth token for request
I/flutter ( 9524): null
W/NetworkRequest( 9524): no auth token for request
I/System.out( 9524): (HTTPLog)-Static: isSBSettingEnabled false
I/System.out( 9524): (HTTPLog)-Static: isSBSettingEnabled false
D/ViewRootImpl@8f09ed9[MainActivity]( 9524): ViewPostIme pointer 0
D/ViewRootImpl@8f09ed9[MainActivity]( 9524): ViewPostIme pointer 1
W/StorageUtil( 9524): no auth token for request
W/NetworkRequest( 9524): no auth token for request
I/System.out( 9524): (HTTPLog)-Static: isSBSettingEnabled false
I/System.out( 9524): (HTTPLog)-Static: isSBSettingEnabled false
W/StorageUtil( 9524): no auth token for request
W/NetworkRequest( 9524): no auth token for request
I/System.out( 9524): (HTTPLog)-Static: isSBSettingEnabled false
I/System.out( 9524): (HTTPLog)-Static: isSBSettingEnabled false
I/flutter ( 9524): https://firebasestorage.googleapis.com/v0/b/bridcodes-seller.appspot.com/o/Products%2Fimage_cropper_1598948384298.jpg?alt=media&token=cc418efc-8402-4a96-a0f0-939a3a171373
W/StorageUtil( 9524): no auth token for request
W/NetworkRequest( 9524): no auth token for request
I/System.out( 9524): (HTTPLog)-Static: isSBSettingEnabled false
I/System.out( 9524): (HTTPLog)-Static: isSBSettingEnabled false

这是我的防火区存储安全规则。

rules_version = '2';
service firebase.storage {
match /b/{bucket}/o {
match /Products/{allPaths=**} {
allow read, write;
}
}
}

Answer 1

Future<String> uploadImageToFirebase() async {
FirebaseStorage _storage = FirebaseStorage.instance;
StorageReference reference = _storage.ref().child("Products/${Path.basename(_image.path)}");
StorageUploadTask uploadTask = reference.putFile(_image);
StorageTaskSnapshot taskSnapshot = await uploadTask.onComplete;
final String url = await taskSnapshot.ref.getDownloadURL();
return url;
}

调用功能

uploadDetails(context) async {
if(_formKey.currentState.validate()) {
_formKey.currentState.save();
if(_image != null) {
imgUrl = await uploadImageToFirebase();
Firestore.instance.collection("Products").add({
'ImgUrl': imgUrl,
});
}
}
}