有效地确定用户是否喜欢在Firebase中发帖 [英] Efficiently determine if user liked post in Firebase

问题描述

我有一个应用程序，用户可以喜欢帖子，我想确定当前用户以前是否以有效的方式喜欢帖子。我的数据目前看起来像这样：

我也存储每个用户喜欢

在我目前的查询中，我我是这样做的：

  if let people = post [peopleWhoLike] as？ [String：AnyObject] {
 if people [（Auth.auth（）。currentUser？.uid）！]！= nil {
 posst.userLiked = true 
} 
} 
  

不过，我相信这需要我下载所有的帖子，所以我试过这个：

  if（post [peopleWhoLike\（Auth.auth（）。currentUser！.uid） ] as？[String：AnyObject]）！= nil {
 posst.userLiked = true 
} 
  

第二种方法似乎没有正常工作。有没有更好的方法来做到这一点？

以下是我的初始查询：

  pagingReference.child （posts）。queryLimited（toLast：5）.observeSingleEvent（of：.value，with：{snap in 
为snap.children中的子元素{
 let child = child as？DataSnapshot $ b $如果让post = child？.value as？[String：AnyObject] {
 let pos = Post（）
如果让author = post [author] as？String，let pathToImage = post [ pathToImage]为？String，让postID = post [postID]为？String，让postDescription = post [postDescription]为？String，让timestamp = post [timestamp]为？Double，让category = post [category] as？String，let table = post [group] as？String，让userID = post [userID]为？String，让numberOfComments = post [numberOfComments]为？ region = post [region] as String，让numLikes = post [likes]作为？Int {
  

解决方案

解决了它：

I在tableView中，我只是直接查询喜欢的值，然后确定要显示的按钮。

  static func userLiked（postID：String，cell：BetterPostCell，indexPath：IndexPath）{
 //需要缓存这些结果，所以我们不会查询多次
 if newsfeedPosts [indexPath.row] .userLiked == false {
如果let uid = Auth.auth（）。currentUser？.uid {
）likeRef.child（userActivity）。child（uid）.child（likes）。child（postID）.queryOrderedByKey（）。observeSingleEvent（of：.value，with：{snap in 
 snap。 exists（）{
 newsfeedPosts [indexPath.row] .userLiked = true 
 cell.helpfulButton.isHidden = true 
 cell.notHelpfulButton.isHidden = false 
} 
} ）
 likeRef.removeAllObservers（）
} 
} 
} 
  

在我的TableView中调用：

  DatabaseFunctions.userLiked（postID：newsf eedPosts [indexPath.row] .postID，cell：cell，indexPath：indexPath）
  

I have an app where users can like posts and I want to determine if the current user has previously liked a post in an efficient manner. My data currently looks like this:

I also store the likes for every user

In my current query I am doing this:

if let people = post["peopleWhoLike"] as? [String: AnyObject] {
      if people[(Auth.auth().currentUser?.uid)!] != nil {
           posst.userLiked = true
      }
}

However, I believe this requires me to download all of the post's likes which isn't very efficient, so I tried this:

 if (post["peopleWhoLike\(Auth.auth().currentUser!.uid)"] as? [String: AnyObject]) != nil {
     posst.userLiked = true
 }

The second method doesn't seem to be working correctly. Is there a better way to do this?

Here is my initial query as well:

pagingReference.child("posts").queryLimited(toLast: 5).observeSingleEvent(of: .value, with: { snap in
        for child in snap.children {
            let child = child as? DataSnapshot
            if let post = child?.value as? [String: AnyObject] {
                let posst = Post()
                if let author = post["author"] as? String, let pathToImage = post["pathToImage"] as? String, let postID = post["postID"] as? String, let postDescription = post["postDescription"] as? String, let timestamp = post["timestamp"] as? Double, let category = post["category"] as? String, let table = post["group"] as? String, let userID = post["userID"] as? String, let numberOfComments = post["numberOfComments"] as? Int, let region = post["region"] as? String, let numLikes = post["likes"] as? Int {

解决方案

Solved it:

In the tableView I just query for the liked value directly and then determine what button to display.

static func userLiked(postID: String, cell: BetterPostCell, indexPath: IndexPath) {
        // need to cache these results so we don't query more than once
        if newsfeedPosts[indexPath.row].userLiked == false {
            if let uid = Auth.auth().currentUser?.uid {
                likeRef.child("userActivity").child(uid).child("likes").child(postID).queryOrderedByKey().observeSingleEvent(of: .value, with: { snap in
                    if snap.exists() {
                        newsfeedPosts[indexPath.row].userLiked = true
                        cell.helpfulButton.isHidden = true
                        cell.notHelpfulButton.isHidden = false
                    }
                })
                likeRef.removeAllObservers()
            }
        }
    }

Called in my TableView:

DatabaseFunctions.userLiked(postID: newsfeedPosts[indexPath.row].postID, cell: cell, indexPath: indexPath)

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