是否可以从 firebase db 中的父节点获取所有子节点？
试图这样说:
我想同时获取所有帖子。
它获取视频但仅获取当前用户的视频。我想同时获取所有用户的视频。 这里有一些代码可以让我更好地理解我在做什么:
fileprivate func fetchAllPost() {
fetchPosts()
fetchAllPostsFromUserIds()
}
fileprivate func fetchAllPostsFromUserIds() {
guard let uid = FIRAuth.auth()?.currentUser?.uid else { return }
FIRDatabase.database().reference().child("posts").child(uid).observeSingleEvent(of: .value, with: { (snapshot) in
guard let userIdsDictionary = snapshot.value as? [String: Any] else { return }
userIdsDictionary.forEach({ (key, value) in
FIRDatabase.fetchUserWithUid(uid: key, completion: { (user) in
self.fetchPostsWithUser(user: user)
})
})
}) { (err) in
print("failed to fetch following users ids:", err)
}
}
var posts = [Post]()
fileprivate func fetchPosts() {
guard let currentUserID = FIRAuth.auth()?.currentUser?.uid else { return }
FIRDatabase.fetchUserWithUid(uid: currentUserID) { (user) in
self.fetchPostsWithUser(user: user)
}
}
fileprivate func fetchPostsWithUser(user: User) {
let ref = FIRDatabase.database().reference().child("posts/\(user.uid)/")
ref.observeSingleEvent(of: .value, with: { (snapshot) in
self.collectionView?.refreshControl?.endRefreshing()
guard let dictionaries = snapshot.value as? [String: Any] else { return }
dictionaries.forEach({ (key,value) in
guard let dictionary = value as? [String: Any] else { return }
var post = Post(user: user, dictionary: dictionary)
post.id = key
guard let uid = FIRAuth.auth()?.currentUser?.uid else { return }
FIRDatabase.database().reference().child("likes").child(key).child(uid).observe(.value, with: { (snapshot) in
if let value = snapshot.value as? Int, value == 1 {
post.hasLiked = true
} else {
post.hasLiked = false
}
self.posts.append(post)
self.posts.sort(by: { (p1, p2) -> Bool in
return p1.creationDate.compare(p2.creationDate) == .orderedDescending
})
self.collectionView?.reloadData()
}, withCancel: { (err) in
print("Failed to fetch info for post")
})
print(self.posts)
})
}) { (error) in
print("Failed to fetch posts", error)
}
}
最佳答案
我不懂 Swift，但你可以获取 FIRDatabase.database().reference().child("posts") 然后遍历 children .
关于ios - 按下按钮时如何添加谷歌地图标记？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46209386/