没有为类型“Object”定义运算符“[]”。尝试定义运算符“[]”

我的代码在以下错误中给出了我在此行中从 firebase 访问用户名时遇到的问题

snapshot.data['username']

它给出了上面提到的错误

我知道访问地图数据的唯一方法是这样

FutureBuilder<Object>(
  future: FirebaseFirestore.instance
   .collection('users')
   .doc(userId)
   .get(),
  builder: (context, snapshot) {
    if (snapshot.connectionState == ConnectionState.waiting) {
      return Text("Loading...");
    }
    return Text(
      snapshot.data['username'],
      style: TextStyle(
        fontWeight: FontWeight.bold,
      ),
    );
  }
),

回答

FutureBuilder<Object>(
  future: FirebaseFirestore.instance
   .collection('users')
   .doc(userId)
   .get(),
  builder: (context, snapshot) {
    if (snapshot.connectionState == ConnectionState.waiting) {
      return Text("Loading...");
    }
    return Text(
      snapshot['username'],
      style: TextStyle(
        fontWeight: FontWeight.bold,
      ),
    );
  }
),