我在以下行“var map = Map .from (snap.snapshot.value);”中的“snap.snapshot.value”参数上出现错误。错误是“参数类型‘对象？’无法分配给参数类型“Map ”。”
class _HomePageState extends State<HomePage> {
List<Posts> postsList = [];
@override
void initState() {
super.initState();
DatabaseReference postsRef = FirebaseDatabase.instance.reference().child("Posts");
postsRef.once().then((snap) {
var map = Map<String, dynamic>.from(snap.snapshot.value); <--- the error is here
postsList.clear();
map.forEach((key, value) {
var values = Map<String,dynamic>.from(map);
Posts posts = Posts
(
values['url'],
values['descrizione'],
values['data'],
values['ora']
);
postsList.add(posts);
});
您会更改如下代码吗？
From
var map = Map<String, dynamic>.from(snap.snapshot.value);
To
Map<String, dynamic> map = snap.snapshot.value as Map<String, dynamic>
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