從firebase檢索唯一受歡迎的帖子

Question

我想檢索只有我從firebase數據庫中收到的帖子。

下面是我的數據。我希望這位喜歡帖子的用戶只在該帖子被該用戶喜歡時才顯示該帖子。

我已經從firebase中檢索數據，但它會顯示所有帖子，而不僅僅是最喜歡的帖子。

下面這段代碼是什麼我使用和它的作品，因爲它顯示的數據，如果我打一樣和不一樣，如果我不同，但是這正顯示出所有數據。

 DataService.ds.REF_USER_CURRENT.observeSingleEvent(of: .value, with: { (snapshot) in 

      if snapshot.hasChild("favourite") { 

       print("true Favourits exist") 


    DataService.ds.REF_POSTS.observe(DataEventType.value, with: { (snapshot) in 
     self.posts = [] 

     if let snapshot = snapshot.children.allObjects as? [DataSnapshot] { 
      for snap in snapshot { 
       print("SNAP: \(snap)") 
       if let postDict = snap.value as? Dictionary<String, AnyObject> { 
        let key = snap.key 
        let post = Post(postKey: key, postData: postDict) 
        self.posts.append(post) 
       } 
      } 
     } 
     self.tableView.reloadData() 

     }) 
      }else { 
       print("Tony: Couldnt get the data") 
      } 

    }) 
} 

下編輯在這裏與VLADS解答>>>>>>>

DataService.ds.REF_USER_CURRENT.observeSingleEvent(of: .value, with: { (snapshot) in 

     if snapshot.hasChild("favourite") { 


    let refToUser = DataService.ds.REF_USER_CURRENT // <- your userId 
    refToUser.child("favourite").observeSingleEvent(of: .value, with: { snapshot in 
     let value = snapshot.value as? NSDictionary 
     let postsIds = value?.allKeys as! [String] 

     for postId in postsIds { 
      let refToPost = Database.database().reference(withPath: "posts/" + postId) 
      refToPost.observeSingleEvent(of: .value, with: { snapshot in 
       if snapshot.exists() { 
       self.notAddedLabel.isHidden = true 
       print("true Favourits exist") 


//  refToPost.observe(DataEventType.value, with: { (snapshot) in 
     self.posts = [] 

     if let snapshot = snapshot.children.allObjects as? [DataSnapshot] { 
      for snap in snapshot { 
       print("SNAP: \(snap)") 
       if let postDict = snap.value as? Dictionary<String, AnyObject> { 
        let key = snap.key 
        let post = Post(postKey: key, postData: postDict) 
        self.posts.append(post) 
       } 
      } 
     } 
     self.tableView.reloadData() 

//   }) 
      }else { 
       self.notAddedLabel.isHidden = false 
       print("Tony: Couldn't get the data") 
       } 
      }) 
     } 
     }) 
     }else { 
      print("Tony: No Favs added, couldn't get the data") 
    } 
}) 
} 

Answer 1

First step:去favourite節點，並得到所有帖子的ID：

let refToUser = FIRDatabase.database().reference(withPath: "Users").child(userId) // <- your userId 
refToUser.child("favourite").observeSingleEvent(of: .value, with: { snapshot in 
     if let value = snapshot.value as? NSDictionary 
     let postsIds = value.allKeys as! [String] 

     // Second step: fetch every post 
     for postId in postsIds { 
      let refToPost = FIRDatabase.database().reference(withPath: "posts/" + postId) 
      refToPost.observeSingleEvent(of: .value, with: { snapshot in 
       if snapshot.exists() { 
        // do whatever you want 
        // snapshot now is your post data 
       } else { 
        print("error") 
       } 
      }) 
     } 

所以，你的主要問題，你參考所有職位，而不是T. o特定的。

希望你有想法。