Question

这是我的工厂。我可以从中访问数据并且可以正常工作：

factory ActivityFeedItem.fromDocument(DocumentSnapshot snap) {
    var doc = snap.data();
    return ActivityFeedItem(
      username: doc['username'],
      userId: doc['userId'],
      type: doc['type'],
      postId: doc['postId'],
      userProfileImg: doc['userProfileImg'],
      commentData: doc['commentData'],
      timestamp: doc['timestamp'],
      mediaUrl: doc['mediaUrl'],
    );
  }

另一方面，我想使用此方法将 postId, userId 传递到另一个屏幕：

showPost(context) {
Navigator.push(
  context,
  MaterialPageRoute(
    builder: (context) => PostScreen(
      postId: postId,
      userId: userId,
    ),
  ),
);

}

这是我来自 Firestore 的数据：

当我通过 userId 或 postId 时出现此错误：

Bad state: cannot get a field on a DocumentSnapshotPlatform that does not exist

这意味着当我尝试将数据传递到另一个屏幕时他找不到数据。 doc['userId'] 和 doc = snap.data，这样就给出了 snap.data["userId], 并且我可以访问相同的 userId 或 PostID。

这是我的 ActivityFeed(Notifications) 类

class ActivityFeed extends StatefulWidget {
  @override
  _ActivityFeedState createState() => _ActivityFeedState();
}

class _ActivityFeedState extends State<ActivityFeed> {
  // getActivityFeed() async {
  //   // QuerySnapshot snapshot = await activityFeedRef
  //   //     .doc(currentUser.id)
  //   //     .collection('feedItems')
  //   //     .orderBy('timestamp', descending: true)
  //   //     .limit(50).snapshots(),
  //   //     .get();
  //   print(snapshot.docs.);
  //   List<ActivityFeedItem> feedItems = [];
  //   snapshot.docs.forEach((doc) {
  //     feedItems.add(ActivityFeedItem.fromDocument(doc));
  //     print('\nItem:');
  //     print('\nItem:');
  //     print('\nItem:');
  //     print('\nItem:');
  //     print('\nItem:');
  //     print('\nItem:');
  //     print('Activity Feed Item: ${doc.data}');
  //     debugPrint('Activity Feed Item: ${feedItems[1]}');
  //     print('\nItem:');
  //     print('\nItem:');
  //     print('\nItem:');
  //     print('\nItem:');
  //     print('\nItem:');
  //     print('\nItem:');
  //     print('\nItem:');
  //   });
  //   return feedItems;
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.orange,
      appBar: header(context, title: "Activity Feed"),
      body: Container(
          child: StreamBuilder<QuerySnapshot>(
        stream: activityFeedRef
            .doc(currentUser.id)
            .collection('feedItems')
            .orderBy('timestamp', descending: true)
            .limit(50)
            .snapshots(),
        builder: (context, snapshot) {
          if (!snapshot.hasData) {
            return Text("No Data");
          }
          List<ActivityFeedItem> feedItem = [];
          snapshot.data.docs.forEach((doc) {
            feedItem.add(ActivityFeedItem.fromDocument(doc));
          });
          // print(feedItem.length);
          return ListView(
            children: feedItem,
          );
        },
      )),
    );
  }
}

Widget mediaPreview;
String activityItemText;

class ActivityFeedItem extends StatelessWidget {
  final String username;
  final String userId;
  final String type; // 'like', 'follow', 'comment'
  final String mediaUrl;
  final String postId;
  final String userProfileImg;
  final String commentData;
  final Timestamp timestamp;

  ActivityFeedItem({
    this.username,
    this.userId,
    this.type,
    this.mediaUrl,
    this.postId,
    this.userProfileImg,
    this.commentData,
    this.timestamp,
  });

  factory ActivityFeedItem.fromDocument(DocumentSnapshot snap) {
    var doc = snap.data();
    return ActivityFeedItem(
      username: doc['username'],
      userId: doc['userId'],
      type: doc['type'],
      postId: doc['postId'],
      userProfileImg: doc['userProfileImg'],
      commentData: doc['commentData'],
      timestamp: doc['timestamp'],
      mediaUrl: doc['mediaUrl'],
    );
  }

  showPost(context) {
    Navigator.push(
      context,
      MaterialPageRoute(
        builder: (context) => PostScreen(
          postId: postId,
          userId: userId,
        ),
      ),
    );
  }

  configureMediaPreview(context) {
    if (type == "like" || type == 'comment') {
      mediaPreview = GestureDetector(
        onTap: () => showPost(context),
        child: Container(
          height: 50.0,
          width: 50.0,
          child: AspectRatio(
              aspectRatio: 16 / 9,
              child: Container(
                decoration: BoxDecoration(
                  image: DecorationImage(
                    fit: BoxFit.cover,
                    image: CachedNetworkImageProvider(mediaUrl),
                  ),
                ),
              )),
        ),
      );
    } else {
      mediaPreview = Text('');
    }

    if (type == 'like') {
      activityItemText = "liked your post";
    } else if (type == 'follow') {
      activityItemText = "is following you";
    } else if (type == 'comment') {
      activityItemText = 'replied: $commentData';
    } else {
      activityItemText = "Error: Unknown type '$type'";
    }
  }

  @override
  Widget build(BuildContext context) {
    configureMediaPreview(context);

    return Padding(
      padding: EdgeInsets.only(bottom: 2.0),
      child: Container(
        color: Colors.white54,
        child: ListTile(
          title: GestureDetector(
            onTap: () => showProfile(context, profileId: userId),
            child: RichText(
              overflow: TextOverflow.ellipsis,
              text: TextSpan(
                  style: TextStyle(
                    fontSize: 14.0,
                    color: Colors.black,
                  ),
                  children: [
                    TextSpan(
                      text: username,
                      style: TextStyle(fontWeight: FontWeight.bold),
                    ),
                    TextSpan(
                      text: ' $activityItemText',
                    ),
                  ]),
            ),
          ),
          leading: CircleAvatar(
            backgroundImage: CachedNetworkImageProvider(userProfileImg),
          ),
          subtitle: Text(
            timeago.format(timestamp.toDate()),
            overflow: TextOverflow.ellipsis,
          ),
          trailing: mediaPreview,
        ),
      ),
    );
  }
}

showProfile(BuildContext context, {String profileId}) {
  Navigator.push(
    context,
    MaterialPageRoute(
      builder: (context) => Profile(
        profileId: profileId,
      ),
    ),
  );
}

这是我的个人资料屏幕

   class Profile extends StatefulWidget {
  final String profileId;

  Profile({this.profileId});

  @override
  _ProfileState createState() => _ProfileState();
}

class _ProfileState extends State<Profile> {
  final String currentUserId = currentUser?.id;
  String postOrientation = "grid";
  bool isFollowing = false;
  bool isLoading = false;
  int postCount = 0;
  int followerCount = 0;
  int followingCount = 0;
  List<Post> posts = [];

  @override
  void initState() {
    super.initState();
    getProfilePosts();
    getFollowers();
    getFollowing();
    checkIfFollowing();
  }

  checkIfFollowing() async {
    DocumentSnapshot doc = await followersRef
        .doc(widget.profileId)
        .collection('userFollowers')
        .doc(currentUserId)
        .get();
    setState(() {
      isFollowing = doc.exists;
    });
  }

  getFollowers() async {
    QuerySnapshot snapshot = await followersRef
        .doc(widget.profileId)
        .collection('userFollowers')
        .get();
    setState(() {
      followerCount = snapshot.docs.length;
    });
  }

  getFollowing() async {
    QuerySnapshot snapshot = await followingRef
        .doc(widget.profileId)
        .collection('userFollowing')
        .get();
    setState(() {
      followingCount = snapshot.docs.length;
    });
  }

  getProfilePosts() async {
    setState(() {
      isLoading = true;
    });
    QuerySnapshot snapshot = await postRef
        .doc(widget.profileId)
        .collection('usersPosts')
        .orderBy('timestamp', descending: true)
        .get();
    setState(() {
      isLoading = false;
      postCount = snapshot.docs.length;
      posts = snapshot.docs.map((doc) => Post.fromDocument(doc)).toList();
    });
  }

  Column buildCountColumn(String label, int count) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        Text(
          count.toString(),
          style: TextStyle(fontSize: 22.0, fontWeight: FontWeight.bold),
        ),
        Container(
          margin: EdgeInsets.only(top: 4.0),
          child: Text(
            label,
            style: TextStyle(
              color: Colors.grey,
              fontSize: 15.0,
              fontWeight: FontWeight.w400,
            ),
          ),
        ),
      ],
    );
  }

  editProfile() {
    Navigator.push(
        context,
        MaterialPageRoute(
            builder: (context) => EditProfile(currentUserId: currentUserId)));
  }

  Container buildButton({String text, Function function}) {
    return Container(
      padding: EdgeInsets.only(top: 2.0),
      child: FlatButton(
        onPressed: function,
        child: Container(
          width: 250.0,
          height: 27.0,
          child: Text(
            text,
            style: TextStyle(
              color: isFollowing ? Colors.black : Colors.white,
              fontWeight: FontWeight.bold,
            ),
          ),
          alignment: Alignment.center,
          decoration: BoxDecoration(
            color: isFollowing ? Colors.white : Colors.blue,
            border: Border.all(
              color: isFollowing ? Colors.grey : Colors.blue,
            ),
            borderRadius: BorderRadius.circular(5.0),
          ),
        ),
      ),
    );
  }

  buildProfileButton() {
    // viewing your own profile - should show edit profile button
    bool isProfileOwner = currentUserId == widget.profileId;
    if (isProfileOwner) {
      return buildButton(
        text: "Edit Profile",
        function: editProfile,
      );
    } else if (isFollowing) {
      return buildButton(
        text: "Unfollow",
        function: handleUnfollowUser,
      );
    } else if (!isFollowing) {
      return buildButton(
        text: "Follow",
        function: handleFollowUser,
      );
    }
  }

  handleUnfollowUser() {
    setState(() {
      isFollowing = false;
    });
    // remove follower
    followersRef
        .doc(widget.profileId)
        .collection('userFollowers')
        .doc(currentUserId)
        .get()
        .then((doc) {
      if (doc.exists) {
        doc.reference.delete();
      }
    });
    // remove following
    followingRef
        .doc(currentUserId)
        .collection('userFollowing')
        .doc(widget.profileId)
        .get()
        .then((doc) {
      if (doc.exists) {
        doc.reference.delete();
      }
    });
    // delete activity feed item for them
    activityFeedRef
        .doc(widget.profileId)
        .collection('feedItems')
        .doc(currentUserId)
        .get()
        .then((doc) {
      if (doc.exists) {
        doc.reference.delete();
      }
    });
  }

  handleFollowUser() {
    setState(() {
      isFollowing = true;
    });
    // Make auth user follower of THAT user (update THEIR followers collection)
    followersRef
        .doc(widget.profileId)
        .collection('userFollowers')
        .doc(currentUserId)
        .set({});
    // Put THAT user on YOUR following collection (update your following collection)
    followingRef
        .doc(currentUserId)
        .collection('userFollowing')
        .doc(widget.profileId)
        .set({});
    // add activity feed item for that user to notify about new follower (us)
    activityFeedRef
        .doc(widget.profileId)
        .collection('feedItems')
        .doc(currentUserId)
        .set({
      "type": "follow",
      "ownerId": widget.profileId,
      "username": currentUser.username,
      "userId": currentUserId,
      "userProfileImg": currentUser.photoUrl,
      "timestamp": timestamp,
    });
  }

  buildProfileHeader() {
    return FutureBuilder(
        future: userRef.doc(widget.profileId).get(),
        builder: (context, snapshot) {
          if (!snapshot.hasData) {
            return circularProgress();
          }
          User user = User.fromDucument(snapshot.data);
          return Padding(
            padding: EdgeInsets.all(16.0),
            child: Column(
              children: <Widget>[
                Row(
                  children: <Widget>[
                    CircleAvatar(
                      radius: 40.0,
                      backgroundColor: Colors.grey,
                      backgroundImage:
                          CachedNetworkImageProvider(user.photoUrl),
                    ),
                    Expanded(
                      flex: 1,
                      child: Column(
                        children: <Widget>[
                          Row(
                            mainAxisSize: MainAxisSize.max,
                            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                            children: <Widget>[
                              buildCountColumn("posts", postCount),
                              buildCountColumn("followers", followerCount),
                              buildCountColumn("following", followingCount),
                            ],
                          ),
                          Row(
                            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                            children: <Widget>[
                              buildProfileButton(),
                            ],
                          ),
                        ],
                      ),
                    ),
                  ],
                ),
                Container(
                  alignment: Alignment.centerLeft,
                  padding: EdgeInsets.only(top: 12.0),
                  child: Text(
                    user.username,
                    style: TextStyle(
                      fontWeight: FontWeight.bold,
                      fontSize: 16.0,
                    ),
                  ),
                ),
                Container(
                  alignment: Alignment.centerLeft,
                  padding: EdgeInsets.only(top: 4.0),
                  child: Text(
                    user.displayName,
                    style: TextStyle(
                      fontWeight: FontWeight.bold,
                    ),
                  ),
                ),
                Container(
                  alignment: Alignment.centerLeft,
                  padding: EdgeInsets.only(top: 2.0),
                  child: Text(
                    user.bio,
                  ),
                ),
              ],
            ),
          );
        });
  }

  buildProfilePosts() {
    if (isLoading) {
      return circularProgress();
    } else if (posts.isEmpty) {
      return Container(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            SvgPicture.asset('assets/images/no_content.svg', height: 260.0),
            Padding(
              padding: EdgeInsets.only(top: 20.0),
              child: Text(
                "No Posts",
                style: TextStyle(
                  color: Colors.redAccent,
                  fontSize: 40.0,
                  fontWeight: FontWeight.bold,
                ),
              ),
            ),
          ],
        ),
      );
    } else if (postOrientation == "grid") {
      List<GridTile> gridTiles = [];
      posts.forEach((post) {
        gridTiles.add(GridTile(child: PostTile(post)));
      });
      return GridView.count(
        crossAxisCount: 3,
        childAspectRatio: 1.0,
        mainAxisSpacing: 1.5,
        crossAxisSpacing: 1.5,
        shrinkWrap: true,
        physics: NeverScrollableScrollPhysics(),
        children: gridTiles,
      );
    } else if (postOrientation == "list") {
      return Column(
        children: posts,
      );
    }
  }

  setPostOrientation(String postOrientation) {
    setState(() {
      this.postOrientation = postOrientation;
    });
  }

  buildTogglePostOrientation() {
    return Row(
      mainAxisAlignment: MainAxisAlignment.spaceEvenly,
      children: <Widget>[
        IconButton(
          onPressed: () => setPostOrientation("grid"),
          icon: Icon(Icons.grid_on),
          color: postOrientation == 'grid'
              ? Theme.of(context).primaryColor
              : Colors.grey,
        ),
        IconButton(
          onPressed: () => setPostOrientation("list"),
          icon: Icon(Icons.list),
          color: postOrientation == 'list'
              ? Theme.of(context).primaryColor
              : Colors.grey,
        ),
      ],
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: header(context, title: "Profile"),
      body: ListView(
        children: <Widget>[
          buildProfileHeader(),
          Divider(),
          buildTogglePostOrientation(),
          Divider(
            height: 0.0,
          ),
          buildProfilePosts(),
        ],
      ),
    );
  }
}

Firebase 使用 Flutter 访问数据收集和文档

0 个答案: