flutter - 带有 Flutter 和 Firestore 的 GridView

Question

我正在尝试从云 firestore 记录制作一个简单的 GridView。我已经关注了很多视频教程，但没有成功。这是代码:

import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';

class EventList extends StatefulWidget {
 @override
 EventListState createState() => new EventListState();
}

class EventListState extends State<EventList> {
  @override
  Widget build(BuildContext context) {
    return StreamBuilder(
      stream: Firestore.instance.collection('events_flutter').snapshots(),
  builder: (BuildContext context, DocumentSnapshot snapshot) {
    if (!snapshot.hasData) {
      return Center(child: const Text('Loading events...'));
    }
    return GridView.builder(
      gridDelegate:
          SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2),
      itemBuilder: (BuildContext context, int index) {
        return Text(snapshot['event_name']);
      },
      itemCount: snapshot.data.documents.length,
    );
  },
);}}

这是将鼠标悬停在“builder: (BuildContext context, DocumentSnapshot snapshot)”上时的错误消息。谁能帮助我了解发生了什么？

非常感谢。

Answer 1

您应该将 snapshot 的类型从 DocumentSnapshot 替换为 AsyncSnapshot。

...

builder: (BuildContext context, AsyncSnapshot snapshot) {
    if (!snapshot.hasData) {
        return Center(child: const Text('Loading events...'));
    }

    ...

此外，您可能想要替换这一行:

return Text(snapshot['event_name']);

为此:

return Text(snapshot.data.documents[index]['event_name']);