Flutter：将firestore快照转换为streambuilder中的列表

Posted 2023-02-23

【中文标题】Flutter：将firestore快照转换为streambuilder中的列表

【英文标题】：Flutter: Convert firestore snapshot to list in streambuilder

【发布时间】：2020-10-26 21:06:35

【问题描述】：

我需要将快照从云存储库转换为列表，我知道这对于显示数据是不必要的，但我需要它根据其他参数重新排序数据，这是我的代码

 Stream chatRooms;
  List item = [];

 Widget chatRoomsList() 
    return StreamBuilder(
      stream: chatRooms,
      builder: (context, snapshot) 
        if (snapshot.hasData &&
            !snapshot.hasError) 
          item = [];

          item = snapshot.data;

          return ListView.builder(
              itemCount: item.length,
              shrinkWrap: true,
              itemBuilder: (context, index) 
                return ChatRoomsTile(
                  otherUserUid:item[index]['arrayUsers']
                      .replaceAll("[", "")
                      .replaceAll(widget.user.uid, "")
                      .replaceAll("]", "")
                      .replaceAll(",", "")
                      .replaceAll(" ", ""),
                  chatRoomId:
                  item[index]["chatRoomId"],
                  user: widget.user,
                );
              );
         else
            return Container();
      ,
    );
  

  @override
  void initState() 
    getUserInfogetChats();
    super.initState();
  

  getUserInfogetChats() async 
    DatabaseMethods().getUserChats(widget.user.uid).then((snapshots) 
      setState(() 
        chatRooms = snapshots;
      );
    );
  

我得到了这个错误

════════ Exception caught by widgets library ═══════════════════════════════════════════════════════
The following _TypeError was thrown building StreamBuilder<dynamic>(dirty, state: _StreamBuilderBaseState<dynamic, AsyncSnapshot<dynamic>>#48820):
type 'QuerySnapshot' is not a subtype of type 'List<dynamic>'

【问题讨论】：

你在哪一行得到错误

@PeterHaddad 在这一行：item = snapshot.data;

【参考方案1】：

变化：

item = snapshot.data;

进入这个：

item = snapshot.data.documents;

documents 应该返回一个List<DocumentSnapshot>，所以还要更改item 的类型：

List<DocumentSnapshot> item = [];