我无法从firebase数据库获取值。
我试图访问值的函数：

class chatPage extends StatefulWidget {
  final String groupId, groupName, userName;
  const chatPage(
      {Key? key,
      required this.groupId,
      required this.groupName,
      required this.userName})
      : super(key: key);

  @override
  State<chatPage> createState() => _chatPageState();
}

class _chatPageState extends State<chatPage> {
  String admin = "";
  Stream<QuerySnapshot>? chats;

  @override
  void initstate() {
    getChatandAdmin();
    super.initState();
  }

  getChatandAdmin() {
    DatabaseService().getChats(widget.groupId).then((val) {
      setState(() {
        chats = val; 
      });
    });
    DatabaseService().getGroupAdmin(widget.groupId).then((value) {
      setState(() {
        admin = value;
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        centerTitle: true,
        title: Text(
          widget.groupName,
          textAlign: TextAlign.center,
        ),
        elevation: 0,
        backgroundColor: Theme.of(context).primaryColor,
        actions: [
          IconButton(
              onPressed: () {
                nextScreen(
                    context,
                    GroupInfo(
                        groupId: widget.groupId,
                        adminName: admin,
                        groupName: widget.groupName));
              },
              icon: const Icon(Icons.info))
        ],
      ),
      body: Center(child: Text(widget.groupId),),
    );
  }
}

在上面的代码中是主类，我试图将值从函数保存到代码中的以下变量。但在看到结果的同时，并没有为其显示价值。
这是数据库类，所有集合引用都在其中创建，并且还包含函数getchat()和getgroupadmin()。
我做错了什么？
数据库服务类：

class DatabaseService {
  final String? uid;
  DatabaseService({this.uid});

  //refrences for collections
  final CollectionReference userCollection =
      FirebaseFirestore.instance.collection("users");
  final CollectionReference groupCollection =
      FirebaseFirestore.instance.collection("groups");

  //saving userdata
  Future savingUserData(String fullName, String email) async {
    return await userCollection.doc(uid).set({
      "fullName": fullName,
      "email": email,
      "groups": [],
      "profilePic": "",
      "uid": uid,
    });
  }

  //getting user data
  Future gettingUserData(String email) async {
    QuerySnapshot snapshot =
        await userCollection.where("email", isEqualTo: email).get();
    return snapshot;
  }

  //get user groups
  getUserGroups() async {
    return userCollection.doc(uid).snapshots();
  }

  // creating a group

  Future createGroup(String userName, String id, String groupName) async {
    DocumentReference groupDocumentRefrence = await groupCollection.add({
      "groupName": groupName,
      "groupIcon": "",
      "admin": "${id}_$userName",
      "members": [],
      "groupId": "",
      "recentMessage": "",
      "recentMessageSender": "",
    });

    //update the members
    await groupDocumentRefrence.update({
      "members": FieldValue.arrayUnion(["${uid}_$userName"]),
      "groupId": groupDocumentRefrence.id,
    });
    DocumentReference userDocumentRefrence = userCollection.doc(uid);
    return await userDocumentRefrence.update({
      "groups":
          FieldValue.arrayUnion(["${groupDocumentRefrence.id}_$groupName"])
    });
  }

//getting the chats
  getChats(String groupId) async {
    return groupCollection
        .doc(groupId)
        .collection("messages")
        .orderBy("time")
        .snapshots();
  }

  Future getGroupAdmin(String groupId) async {
    DocumentReference d = groupCollection.doc(groupId);
    DocumentSnapshot documentSnapshot = await d.get();
    return documentSnapshot['admin'];
  }
}

• • 调用getGroupAdmin函数时不从数据库中取值**