颤振-菲恢复"The argument type 'Map<String, dynamic> Function()' can't be assigned to the paramet

Question

我试图在firebase firestore中查看我的数据。但这个错误出现在我的firestore_service.dart文件中。你能帮我解决这个错误吗。

">参数类型'Map<字符串，动态>Function(('不能分配给参数类型'Map<字符串，动态>"；

这是我的firestore_service.dart

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:esrimarket/note.dart';
import 'package:flutter/foundation.dart';
class FirestoreService {
static final FirestoreService _firestoreService =
FirestoreService._internal();
Firestore _db = Firestore.instance;
FirestoreService._internal();
factory FirestoreService() {
return _firestoreService;
}
getNotes(){
return _db
.collection('notes')
.snapshots()
.map((snapshot)=>snapshot.documents.map((doc)=>Note.fromMap(doc.data, doc.documentID)));
}
}

这是我的note.dart文件

class Note{
final String name;
final String price;
final String quantity;
final String id;
Note({this.name, this.price, this.quantity, this.id});
Note.fromMap(Map<String,dynamic> data, String id):
name=data["name"],
price=data["price"],
quantity=data["quantity"],
id=id;
}

Answer 1

成员data后面缺少括号，因为它是一个函数：

Note.fromMap(doc.data(), doc.documentID)
^^