喜歡/不喜歡Firebase的交易？

Question

我正在嘗試使用Firebase構建社交應用。所以，基本上我有一個Post類，這是類似於在火力地堡docs/guides

public class Post { 

     String uid; 
     String timeStamp; 
     String author; 
     String body; 
     int starCount = 0; 
     Map<String, Boolean> stars = new HashMap<>(); 

     public Post() { 
      // Default constructor required for calls to DataSnapshot.getValue(Post.class) 
     } 

     public Post(String uid, String author, String body, String timeStamp) { 
      this.uid = uid; 
      this.author = author; 
      this.body = body; 
      this.timeStamp = timeStamp; 
     } 

     @Exclude 
     public Map<String, Object> toMap() { 
      HashMap<String, Object> result = new HashMap<>(); 
      result.put("uid", uid); 
      result.put("author", author); 
      result.put("body", body); 
      result.put("starCount", starCount); 
      result.put("stars", stars); 
      result.put("time", timeStamp); 
      return result; 
} 

} 

我用同樣的方法writeNewPost()保存一個新的職位，但因爲stars的HashMap是空的開始，給定星星小孩永遠不會被創建爲「posts」節點中的子節點。

後來當我嘗試使用postRef.getValue(Post.class)或postRef.setValue(Post.class)時，出現錯誤，告訴我沒有可用的可序列化數據。 我嘗試了明顯的解決辦法，並試圖做到這一點，其工作完全正常 -

  //this didn't work 
      //Post post = postSnapShot.getValue(Post.class); 

      Post post = new Post(); 

      post.uid = postSnapShot.child("uid").getValue(String.class); 
      post.body = postSnapShot.child("body").getValue(String.class); 
      post.starCount = postSnapShot.child("starCount").getValue(Integer.class); 
      post.timeStamp = postSnapShot.child("time").getValue(String.class); 
      post.author = postSnapShot.child("author").getValue(String.class); 

但是，當我嘗試實施類似/不同的功能，如火力地堡文檔是這樣的

public boolean likeOrUnlikePost(String postId, final String uid) { 

    DatabaseReference postRef = databaseReference.child(Constants.POSTS).child(postId); 

    postRef.runTransaction(new Transaction.Handler() { 
     @Override 
     public Transaction.Result doTransaction(MutableData mutableData) { 
      //Post p = mutableData.getValue(Post.class); 
      // above line didn't work again, so used the same workaround 
      Post post = new Post(); 
      post.uid = mutableData.child("uid").getValue(String.class); 
      post.body = mutableData.child("body").getValue(String.class); 
      post.starCount = mutableData.child("starCount").getValue(Integer.class); 
      post.timeStamp = mutableData.child("time").getValue(String.class); 
      post.author = mutableData.child("author").getValue(String.class); 
      post.stars = mutableData.child("stars").getValue(Map.class); 
      if (post == null) { 
       return Transaction.success(mutableData); 
      } 

      if (post.stars.containsKey(uid)) { 
       // Unstar the post and remove self from stars 
       post.starCount = post.starCount - 1; 
       post.stars.remove(uid); 
      } else { 
       // Star the post and add self to stars 
       post.starCount = post.starCount + 1; 
       post.stars.put(uid, true); 
      } 

      // below line didn't work as well 
      // mutableData.setValue(post); 


      //so I tried this which doesn't work as I assumed it to work. 
      mutableData.child("starCount").setValue(post.starCount); 
      mutableData.child("stars").setValue(post.stars); 

      return Transaction.success(mutableData); 
     } 

     @Override 
     public void onComplete(DatabaseError databaseError, boolean b, 
           DataSnapshot dataSnapshot) { 
      // Transaction completed 
      Log.d(TAG, "postTransaction:onComplete:" + databaseError); 
     } 
    }); 

    return true; 
} 

再次提到

所以，我堅持與mutableData.setValue()哪些沒有工作。 我該如何解決這個問題？錯誤在這條線

編輯 -

棧跟蹤

Post p = mutableData.getValue(Post.class); 

postTransaction：的onComplete：DatabaseError：從火力地堡數據庫runloop稱爲用戶代碼拋出異常： com.google.firebase。 database.DatabaseException：在com.google.android.gms.internal.zzamy $ zza上的類com.dark.confess.Post 上找不到序列化的屬性。（未知源） at com.google.android.gms.internal。 zzamy.zzj（未知來源） at com.google.android.gms.internal.zzamy.zze（Unknown Source） at com.google.android.gms.internal.zzamy.zzb（Unknown Source） at com.google.android.gms.internal。 zzamy.zza（Unknown Source） at com.google.firebase.database.MutableData.getValue（Unknown Source） at com.dark.confess.FireBaseHelper $ 5.doTransaction（FireBaseHelper.java:120） at com.google.android .gms.internal.zzajb.zza（Unknown Source） at com.google.firebase.database.DatabaseReference $ 4.run（Unknown Source） at java.util.concurrent.Executors $ RunnableAdapter.call（Executors.java:423） at java.util.concurrent.FutureTask.r聯合國（FutureTask.java:237） 在java.util.concurrent.ScheduledThreadPoolExecutor中的$ ScheduledFutureTask.run（ScheduledThreadPoolExecutor.java:269） 在java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1113） 是java。 util.concurrent.ThreadPoolExecutor $ Worker.run（ThreadPoolExecutor.java:588） 在java.lang.Thread.run（Thread.java:818）

Answer 1

在DataSnapshot.getValue()方法No properties to serialize意味着你缺少的getter是否Post class'fields

public class Post { 
    private String uid; 
    private String timeStamp; 
    private String author; 
    private String body; 
    private int starCount; 
    private Map<String, Boolean> stars; 

    public Post() { 
    } 

    public String getUid() { 
     return uid; 
    } 

    public String getTimeStamp() { 
     return timeStamp; 
    } 

    public String getAuthor() { 
     return author; 
    } 

    public String getBody() { 
     return body; 
    } 

    public int getStarCount() { 
     return starCount; 
    } 

    public Map<String, Boolean> getStars() { 
     return stars; 
    } 
}