Firebase - 跨多个位置的原子写入不起作用

Question

如何使用此功能更新 Firebase 中的实时数据库？我设法使该功能正常工作，但仅在触发 updateChild 时为帖子编写新 ID。如何通过帖子 ID 更新当前帖子？

   var pathToPictures = [Pictures]()
   func updateAllImagesOfCurrentUserInDatabase() {

    //refrences
    let ref = FIRDatabase.database().reference()
    let uid = FIRAuth.auth()?.currentUser?.uid

    //match the user ID value stored into posts with current userID and get all the posts of the user
    let update = ref.child("posts").queryOrdered(byChild: "userID").queryEqual(toValue: uid)
    update.observe(FIRDataEventType.value, with: { (snapshot) in
           // print(snapshot)

        self.pathToPictures.removeAll()

        if snapshot.key != nil {

        let results = snapshot.value as! [String : AnyObject]

        for (_, value) in results {
            let pathToPostPicture = Pictures()

            if let pathToImage = value["pathToImage"] as? String , let postID = value["postID"] as? String {
                pathToPostPicture.postImageUrl = pathToImage
                pathToPostPicture.postID = postID
                self.pathToPictures.append(pathToPostPicture)
                print("Image and POST ID: \(pathToPostPicture.postImageUrl!)")
                print("Post ID is : \(postID)")

                if FIRAuth.auth()?.currentUser?.uid == uid {
                ref.child("Users_Details").child(uid!).child("profileImageUrl").observeSingleEvent(of: .value, with: { (userSnapshot) in
                    print(userSnapshot)

                    let userIMageUrl = userSnapshot.value as! String
                    pathToPostPicture.postImageUrl = userIMageUrl
                    self.pathToPictures.append(pathToPostPicture)
                    print("This is the image path:" + userIMageUrl + String(self.pathToPictures.count))

                    // Generate the path
                    let newPostRef = ref.child("posts").childByAutoId()
                    let newKey = newPostRef.key as String
                    print(newKey)
                    let updatedUserData = ["posts/\(postID)/pathToImage": pathToPostPicture.postImageUrl]
                    print("This is THE DATA:" , updatedUserData)
                    ref.updateChildValues(updatedUserData as Any as! [AnyHashable : Any])

                })

                }

                print(self.pathToPictures.count)

            }

            }
        } else {
            print("snapshot is nill")

        }

        self.collectionView?.reloadData()

    })
}

更新：这就是我的数据库的样子

这是我的数据库：

 "Users_Details" : {
    "aR0nRArjWVOhHbBFB8yUfao64z62" : {
      "profileImageUrl" : "url",
      "userID" : "aR0nRArjWVOhHbBFB8yUfao64z62"
    },
    "oGxXznrS2DS4ic1ejcSfKB5UlIQ2" : {
      "profileImageUrl" : "url",
      "userID" : "oGxXznrS2DS4ic1ejcSfKB5UlIQ2"
    }
  },
  "posts" : {
    "-KlzNLcofTgqJgfTaGN9" : {
      "fullName" : "full name",
      "interval" : 1.496785712879506E9,
      "normalDate" : "Tue, 06 Jun 2017 22:48",
      "pathToImage" : "url",
      "userID" : "oGxXznrS2DS4ic1ejcSfKB5UlIQ2"
    },
    "-KlzNXfvecIwBatXxmGW" : {
      "fullName" : "full name",
      "interval" : 1.496785761349721E9,
      "normalDate" : "Tue, 06 Jun 2017 22:49",
      "pathToImage" : "url",
      "userID" : "oGxXznrS2DS4ic1ejcSfKB5UlIQ2"
    },

让我告诉你它的作用：它循环浏览帖子并找到所有当前用户的帖子。然后它获取每个帖子的图像 url 的路径并将其分配给一个数组。之后，它会找到图像 url 的当前用户路径并用它更新整个数组。现在，我不知道如何使用新值更新数据库。如果有人知道，将不胜感激！

我希望在多个位置进行原子写入。有人可以告诉我如何修复我的代码来做到这一点吗？

它看起来像这样：

 // ATOMIC UPDATE HERE - IF SOMEBODY CAN FIND THE RIGHT WAY OF DOING THAT

                    // Generate a new push ID for the new post
                    let newPostRef = ref.child(byAppendingPath: "posts").childByAutoId()
                    let newPostKey = newPostRef.key
                    // Create the data we want to update
                    let updatedUserData = ["posts/\(newPostKey)": ["pathToImage": self.pathToPictures]] as [String : Any]

                    // Do a deep-path update
                    ref.updateChildValues(updatedUserData)

Answer 1

您似乎要下载大量重复数据。虽然数据库的非规范化是一种很好的做法，但我认为在这种情况下，最好不要在每篇文章中包含相同的下载 URL。它不会对少数帖子产生影响，但如果您有数千个用户和数万或数十万个帖子，那么需要下载大量额外数据。相反，您可以有一个包含 uids 作为键和配置文件 imageUrl 作为值的字典。您可以在字典中检查所需的 uid，如果它不存在，请在数据库中查询该用户的 User_Details，然后将它们添加到字典中。当您需要显示图像时，您将从该字典中获取 url。其他人可能对此有更好的建议，所以我欢迎其他想法。

如果您希望在每个帖子中都保留个人资料图片，那么我建议您使用 Cloud Functions for Firebase。您可以创建一个函数，当profileImageUrl 在用户的User_Details 中更新时，然后在其他帖子中更新此条目。目前，Cloud Functions 仅在 Node.js 中可用。如果您不了解 JS，请不要让它成为一种威慑！学习一点 JS 绝对值得。并且这些示例向您展示了您必须知道的尽可能多的 JS 才能开始使用。 查看这些资源：

Getting Started with Cloud Functions for Firebase

GitHub samples

Cloud Functions for Firebase documentation

Writing a Database Trigger

Writing a Cloud Storage Trigger: Part 1

Writing a Cloud Storage Trigger: Part 2

Answer 2

在逻辑上挣扎了几天后，我终于明白了。如果有人会遇到这样的事情，这就是答案。在我的情况下，它是关于当用户更改他的图像时更新当前用户的所有帖子（我的帖子使用非规范化，所以每个图像路径都是不同的）。它将遍历帖子，找到与他的用户 ID 匹配的当前用户帖子 ID，将它们放入数组中，找到 currentUser 图片并使用图像路径更新该数组。最后将更新 Firebase 数据库！

var pathToPictures = [Pictures]()
func updateAllImagesOfCurrentUserInDatabase() {

    //refrences
    let ref = FIRDatabase.database().reference()
    let uid = FIRAuth.auth()?.currentUser?.uid

    //match the user ID value stored into posts with current userID and get all the posts of the user
    let update = ref.child("posts").queryOrdered(byChild: "userID").queryEqual(toValue: uid)
    update.observe(FIRDataEventType.value, with: { (snapshot) in
        self.pathToPictures.removeAll()

        if snapshot.value as? [String : AnyObject] != nil {
        let results = snapshot.value as! [String : AnyObject]

        for (_, value) in results {
            let pathToPostPicture = Pictures()

            if let pathToImage = value["pathToImage"] as? String , let postID = value["postID"] as? String {
                pathToPostPicture.postImageUrl = pathToImage
                pathToPostPicture.postID = postID
                self.pathToPictures.append(pathToPostPicture)
                print("Image and POST ID: \(pathToPostPicture.postImageUrl!)")
                print("Post ID is : \(postID)")

                if FIRAuth.auth()?.currentUser?.uid == uid {
                ref.child("Users_Details").child(uid!).child("profileImageUrl").observeSingleEvent(of: .value, with: { (userSnapshot) in
                    print(userSnapshot)

                    let userIMageUrl = userSnapshot.value as! String
                    pathToPostPicture.postImageUrl = userIMageUrl
                    self.pathToPictures.append(pathToPostPicture)
                    print("This is the image path:" + userIMageUrl + String(self.pathToPictures.count))

                    // Update the Database

                    let postIDCount = pathToPostPicture.postID!
                    let updatedUserData = ["posts/\(postIDCount)/pathToImage": pathToPostPicture.postImageUrl!]
                    print("This is THE DATA:" , updatedUserData)
                    ref.updateChildValues(updatedUserData as Any as! [AnyHashable : Any])

                })
                }
                print(self.pathToPictures.count)
            }
            }
        } else {
            print("snapshot is nill - add some data")
        }

        self.collectionView?.reloadData()
    })
}